busio – Hardware accelerated external bus access

The busio module contains classes to support a variety of serial protocols.

When the microcontroller does not support the behavior in a hardware accelerated fashion it may internally use a bitbang routine. However, if hardware support is available on a subset of pins but not those provided, then a RuntimeError will be raised. Use the bitbangio module to explicitly bitbang a serial protocol on any general purpose pins.

All classes change hardware state and should be deinitialized when they are no longer needed if the program continues after use. To do so, either call deinit() or use a context manager. See Lifetime and ContextManagers for more info.

For example:

import busio
from board import *

i2c = busio.I2C(SCL, SDA)
print(i2c.scan())
i2c.deinit()

This example will initialize the the device, run scan() and then deinit() the hardware. The last step is optional because CircuitPython automatically resets hardware after a program finishes.

Note that drivers will typically handle communication if provided the bus instance (such as busio.I2C(board.SCL, board.SDA)), and that many of the methods listed here are lower level functionalities that are needed for working with custom drivers.

Tutorial for I2C and SPI: https://learn.adafruit.com/circuitpython-basics-i2c-and-spi

Tutorial for UART: https://learn.adafruit.com/circuitpython-essentials/circuitpython-uart-serial

Available on these boards
  • 01Space 0.42 OLED ESP32C3
  • 0xCB Helios
  • 42. Keebs Frood
  • 8086 Commander
  • @sarfata shIRtty
  • AITHinker ESP32-C3S_Kit
  • AITHinker ESP32-C3S_Kit_2M
  • ARAMCON Badge 2019
  • ARAMCON2 Badge
  • ATMegaZero ESP32-S2
  • Adafruit BLM Badge
  • Adafruit CLUE nRF52840 Express
  • Adafruit Camera
  • Adafruit Circuit Playground Bluefruit
  • Adafruit Circuit Playground Express 4-H
  • Adafruit CircuitPlayground Express
  • Adafruit CircuitPlayground Express with Crickit libraries
  • Adafruit CircuitPlayground Express with displayio
  • Adafruit EdgeBadge
  • Adafruit Feather Bluefruit Sense
  • Adafruit Feather ESP32 V2
  • Adafruit Feather ESP32-S2 Reverse TFT
  • Adafruit Feather ESP32-S2 TFT
  • Adafruit Feather ESP32-S3 Reverse TFT
  • Adafruit Feather ESP32-S3 TFT
  • Adafruit Feather ESP32S2
  • Adafruit Feather ESP32S3 4MB Flash 2MB PSRAM
  • Adafruit Feather ESP32S3 No PSRAM
  • Adafruit Feather HUZZAH32
  • Adafruit Feather M0 Adalogger
  • Adafruit Feather M0 Basic
  • Adafruit Feather M0 Express
  • Adafruit Feather M0 Express with Crickit libraries
  • Adafruit Feather M0 RFM69
  • Adafruit Feather M0 RFM9x
  • Adafruit Feather M4 CAN
  • Adafruit Feather M4 Express
  • Adafruit Feather MIMXRT1011
  • Adafruit Feather RP2040
  • Adafruit Feather RP2040 CAN
  • Adafruit Feather RP2040 DVI
  • Adafruit Feather RP2040 Prop-Maker
  • Adafruit Feather RP2040 RFM
  • Adafruit Feather RP2040 Scorpio
  • Adafruit Feather RP2040 ThinkInk
  • Adafruit Feather RP2040 USB Host
  • Adafruit Feather STM32F405 Express
  • Adafruit Feather nRF52840 Express
  • Adafruit FunHouse
  • Adafruit Gemma M0
  • Adafruit Gemma M0 PyCon 2018
  • Adafruit Grand Central M4 Express
  • Adafruit HUZZAH32 Breakout
  • Adafruit Hallowing M4 Express
  • Adafruit ItsyBitsy M0 Express
  • Adafruit ItsyBitsy M4 Express
  • Adafruit ItsyBitsy RP2040
  • Adafruit ItsyBitsy nRF52840 Express
  • Adafruit KB2040
  • Adafruit LED Glasses Driver nRF52840
  • Adafruit Macropad RP2040
  • Adafruit MagTag
  • Adafruit Matrix Portal M4
  • Adafruit MatrixPortal S3
  • Adafruit Metro ESP32S2
  • Adafruit Metro ESP32S3
  • Adafruit Metro M0 Express
  • Adafruit Metro M4 Airlift Lite
  • Adafruit Metro M4 Express
  • Adafruit Metro RP2040
  • Adafruit Metro nRF52840 Express
  • Adafruit Monster M4SK
  • Adafruit ProxLight Trinkey M0
  • Adafruit PyGamer
  • Adafruit PyPortal
  • Adafruit PyPortal Pynt
  • Adafruit PyPortal Titano
  • Adafruit PyRuler
  • Adafruit Pybadge
  • Adafruit QT Py ESP32 PICO
  • Adafruit QT Py ESP32-S3 4MB Flash 2MB PSRAM
  • Adafruit QT Py ESP32-S3 no psram
  • Adafruit QT Py ESP32C3
  • Adafruit QT Py ESP32S2
  • Adafruit QT Py M0
  • Adafruit QT Py M0 Haxpress
  • Adafruit QT Py RP2040
  • Adafruit QT2040 Trinkey
  • Adafruit Trellis M4 Express
  • Adafruit Trinket M0
  • Adafruit-Qualia-S3-RGB666
  • AloriumTech Evo M51
  • Arduino MKR Zero
  • Arduino MKR1300
  • Arduino Nano 33 BLE
  • Arduino Nano 33 IoT
  • Arduino Nano ESP32
  • Arduino Nano RP2040 Connect
  • Arduino Zero
  • Artisense Reference Design RD00
  • AtelierDuMaker nRF52840 Breakout
  • BBQ20KBD
  • BDMICRO VINA-D21
  • BDMICRO VINA-D51
  • BLE-SS dev board Multi Sensor
  • BLOK
  • BPI-Bit-S2
  • BPI-Leaf-S3
  • BPI-PicoW-S3
  • BastBLE
  • BastWiFi
  • Bee-Data-Logger
  • Bee-Motion-S3
  • Bee-S3
  • BlueMicro833
  • BlueMicro840
  • COSMO-Pico
  • CP Sapling M0
  • CP Sapling M0 w/ SPI Flash
  • CP32-M4
  • CRCibernetica IdeaBoard
  • Capable Robot Programmable USB Hub
  • Cedar Grove StringCar M0 Express
  • Challenger NB RP2040 WiFi
  • Challenger RP2040 LTE
  • Challenger RP2040 LoRa
  • Challenger RP2040 SD/RTC
  • Challenger RP2040 SubGHz
  • Challenger RP2040 WiFi
  • Challenger RP2040 WiFi/BLE
  • Circuit Playground Express Digi-Key PyCon 2019
  • CircuitBrains Basic
  • CircuitBrains Deluxe
  • CrumpS2
  • Cytron Maker Feather AIoT S3
  • Cytron Maker Nano RP2040
  • Cytron Maker Pi RP2040
  • Cytron Maker Zero SAMD21
  • DFRobot Beetle ESP32-C3
  • Datanoise PicoADK
  • Deneyap Kart
  • Deneyap Kart 1A
  • Deneyap Kart 1A v2
  • Deneyap Kart G
  • Deneyap Mini
  • Deneyap Mini v2
  • Diodes Delight Piunora
  • DynOSSAT-EDU-EPS
  • DynOSSAT-EDU-OBC
  • DynaLoRa_USB
  • E-Fidget
  • ELECFREAKS PICO:ED
  • ES3ink
  • ESP 12k NodeMCU
  • ESP32 Devkit V1
  • ESP32-C3-DevKitM-1
  • ESP32-C6-DevKitC-1-N8
  • ESP32-C6-DevKitM-1
  • ESP32-H2-DevKitM-1
  • ESP32-S2-DevKitC-1-N4
  • ESP32-S2-DevKitC-1-N4R2
  • ESP32-S2-DevKitC-1-N8R2
  • ESP32-S3-Box-2.5
  • ESP32-S3-Box-Lite
  • ESP32-S3-DevKitC-1-N32R8
  • ESP32-S3-DevKitC-1-N8
  • ESP32-S3-DevKitC-1-N8R2
  • ESP32-S3-DevKitC-1-N8R8
  • ESP32-S3-DevKitC-1-N8R8-with-HACKTABLET
  • ESP32-S3-DevKitM-1-N8
  • ESP32-S3-EYE
  • ESP32-S3-USB-OTG-N8
  • Electrolama minik
  • Electronic Cats Bast Pro Mini M0
  • Electronic Cats CatWAN USBStick
  • Electronic Cats Hunter Cat NFC
  • Electronic Cats NFC Copy Cat
  • Electronut Labs Blip
  • Electronut Labs Papyr
  • EncoderPad RP2040
  • Escornabot Makech
  • Espressif ESP32-EYE
  • Espressif ESP32-LyraT
  • Espressif-ESP32-S3-LCD-EV-Board
  • Espruino Bangle.js 2
  • Espruino Pico
  • Espruino Wifi
  • Feather MIMXRT1011
  • Feather MIMXRT1062
  • FeatherS2
  • FeatherS2 Neo
  • FeatherS2 PreRelease
  • FeatherS3
  • Fig Pi
  • Fluff M0
  • Franzininho WIFI w/Wroom
  • Franzininho WIFI w/Wrover
  • Gravitech Cucumber M
  • Gravitech Cucumber MS
  • Gravitech Cucumber R
  • Gravitech Cucumber RS
  • HMI-DevKit-1.1
  • Hack Club Sprig
  • Hacked Feather M0 Express with 8Mbyte SPI flash
  • HalloWing M0 Express
  • Hardkernel Odroid Go
  • HexKyS2
  • HiiBot BlueFi
  • IMXRT1010-EVK
  • IMXRT1015-EVK
  • IkigaiSense Vita nRF52840
  • IoTs2
  • J&J Studios datum-Distance
  • J&J Studios datum-IMU
  • J&J Studios datum-Light
  • J&J Studios datum-Weather
  • Kaluga 1
  • LILYGO T-DISPLAY
  • LILYGO TEMBED ESP32S3
  • LILYGO TTGO T-01C3
  • LILYGO TTGO T-DISPLAY v1.1
  • LILYGO TTGO T-OI PLUS
  • LILYGO TTGO T8 ESP32-S2
  • LILYGO TTGO T8 ESP32-S2 w/Display
  • LOLIN S3 16MB Flash 8MB PSRAM
  • LOLIN S3 MINI 4MB Flash 2MB PSRAM
  • Lilygo T-watch 2020 V3
  • LoC BeR M4 base board
  • Luatos Core-ESP32C3
  • M5STACK STAMP-C3
  • M5Stack Atom Echo
  • M5Stack Atom Lite
  • M5Stack Atom Matrix
  • M5Stack Atom U
  • M5Stack AtomS3 Lite
  • M5Stack AtomS3U
  • M5Stack Core Basic
  • M5Stack Core Fire
  • M5Stack Core2
  • M5Stack M5Paper
  • M5Stack Stick C
  • M5Stack Stick C Plus
  • M5Stack Timer Camera X
  • MDBT50Q-DB-40
  • MDBT50Q-RX Dongle
  • MEOWBIT
  • MORPHEANS MorphESP-240
  • Maker badge by Czech maker
  • MakerDiary nRF52840 MDK
  • MakerDiary nRF52840 MDK USB Dongle
  • MakerFabs-ESP32-S3-Parallel-TFT-With-Touch-7inch
  • Makerdiary M60 Keyboard
  • Makerdiary Pitaya Go
  • Makerdiary nRF52840 Connect Kit
  • Makerdiary nRF52840 M.2 Developer Kit
  • Melopero Shake RP2040
  • Meow Meow
  • Metro MIMXRT1011
  • MicroDev microC3
  • MicroDev microS2
  • Mini SAM M4
  • MixGo CE
  • NUCLEO F446RE
  • NUCLEO STM32F746
  • NUCLEO STM32F767
  • NUCLEO STM32H743
  • NanoS3
  • Neuron
  • OPENMV-H7 R1
  • Oak Dev Tech BREAD2040
  • Oak Dev Tech Cast-Away RP2040
  • Oak Dev Tech PixelWing ESP32S2
  • Open Hardware Summit 2020 Badge
  • PCA10056 nRF52840-DK
  • PCA10059 nRF52840 Dongle
  • PCA10100 nRF52833 DK
  • PYB LR Nano V2
  • Pajenicko PicoPad
  • Particle Argon
  • Particle Boron
  • Particle Xenon
  • PewPew 10.2
  • PewPew LCD
  • PewPew M4
  • PicoPlanet
  • PillBug
  • Pimoroni Badger 2040
  • Pimoroni Badger 2040 W
  • Pimoroni Inky Frame 5.7
  • Pimoroni Interstate 75
  • Pimoroni Keybow 2040
  • Pimoroni Motor 2040
  • Pimoroni PGA2040
  • Pimoroni Pico DV Base W
  • Pimoroni Pico LiPo (16MB)
  • Pimoroni Pico LiPo (4MB)
  • Pimoroni Pico dv Base
  • Pimoroni PicoSystem
  • Pimoroni Plasma 2040
  • Pimoroni Plasma 2040W
  • Pimoroni Servo 2040
  • Pimoroni Tiny 2040 (2MB)
  • Pimoroni Tiny 2040 (8MB)
  • ProS3
  • PyCubedv04
  • PyCubedv04-MRAM
  • PyCubedv05
  • PyCubedv05-MRAM
  • PyKey 18 Numpad
  • PyKey 44 Ergo
  • PyKey 60
  • PyKey 87 TKL
  • PyboardV1_1
  • RP2.65-F
  • RP2040 Stamp
  • Raspberry Pi 4B
  • Raspberry Pi Compute Module 4
  • Raspberry Pi Compute Module 4 IO Board
  • Raspberry Pi Pico
  • Raspberry Pi Pico W
  • Raspberry Pi Zero
  • Raspberry Pi Zero 2W
  • Raspberry Pi Zero W
  • Robo HAT MM1 M4
  • S2Mini
  • S2Pico
  • SAM E54 Xplained Pro
  • SAM32v26
  • SPRESENSE
  • SSCI ISP1807 Dev Board
  • SSCI ISP1807 Micro Board
  • ST STM32F746G Discovery
  • STM32F411E_DISCO
  • STM32F412G_DISCO
  • STM32F4_DISCO
  • Saola 1 w/Wroom
  • Saola 1 w/Wrover
  • Seeed Studio XIAO ESP32C3
  • Seeed XIAO nRF52840 Sense
  • Seeeduino Wio Terminal
  • Seeeduino XIAO
  • Seeeduino XIAO RP2040
  • Serpente
  • SiLabs xG24 Dev Kit
  • SiLabs xG24 Explorer Kit
  • Silicognition LLC M4-Shim
  • Silicognition LLC RP2040-Shim
  • Simmel
  • SparkFun LUMIDrive
  • SparkFun MicroMod RP2040 Processor
  • SparkFun MicroMod SAMD51 Processor
  • SparkFun MicroMod nRF52840 Processor
  • SparkFun Pro Micro RP2040
  • SparkFun Pro nRF52840 Mini
  • SparkFun Qwiic Micro
  • SparkFun RedBoard Turbo
  • SparkFun SAMD21 Dev Breakout
  • SparkFun SAMD21 Mini Breakout
  • SparkFun STM32 MicroMod Processor
  • SparkFun Teensy MicroMod Processor
  • SparkFun Thing Plus - RP2040
  • SparkFun Thing Plus - SAMD51
  • SparkFun Thing Plus - STM32
  • Sparkfun Thing Plus MGM240P
  • Sprite_v2b
  • StackRduino M0 PRO
  • Swan R5
  • TG-Boards' Datalore IP M4
  • TG-Watch
  • THUNDERPACK_v11
  • THUNDERPACK_v12
  • TTGO T8 ESP32-S2-WROOM
  • Targett Module Clip w/Wroom
  • Targett Module Clip w/Wrover
  • Teensy 4.0
  • Teensy 4.1
  • Teknikio Bluebird
  • The Open Book Feather
  • TinkeringTech ScoutMakes Azul
  • TinyPICO
  • TinyPICO Nano
  • TinyS2
  • TinyS3
  • Trinket M0 Haxpress
  • UARTLogger II
  • VCC-GND Studio YD RP2040
  • VCC-GND YD-ESP32-S3 (N16R8)
  • VCC-GND YD-ESP32-S3 (N8R8)
  • W5100S-EVB-Pico
  • W5500-EVB-Pico
  • WarmBit BluePixel nRF52840
  • Waveshare ESP32-S2-Pico
  • Waveshare ESP32-S2-Pico-LCD
  • Waveshare ESP32-S3-Pico
  • Waveshare RP2040-LCD-0.96
  • Waveshare RP2040-LCD-1.28
  • Waveshare RP2040-Plus (16MB)
  • Waveshare RP2040-Plus (4MB)
  • Waveshare RP2040-Zero
  • WeAct Studio Pico
  • WeAct Studio Pico 16MB
  • Wemos Lolin C3 Mini" // from Wemos MP
  • Wemos Lolin C3 Pico" // from Wemos MP
  • Winterbloom Big Honking Button
  • Winterbloom Sol
  • XinaBox CC03
  • XinaBox CS11
  • iLabs Challenger 840
  • iMX RT 1020 EVK
  • iMX RT 1040 EVK
  • iMX RT 1050 EVKB
  • iMX RT 1060 EVK
  • iMX RT 1060 EVKB
  • keithp.com snekboard
  • micro:bit v2
  • nanoESP32-S2 w/Wrover
  • nanoESP32-S2 w/Wroom
  • ndGarage[n°] Bit6: FeatherSnow-v2
  • ndGarage[n°]Bit6:FeatherSnow
  • nice!nano
  • nullbits Bit-C PRO
  • senseBox MCU
  • splitkb.com Liatris
  • stm32f411ce-blackpill
  • stm32f411ce-blackpill-with-flash
  • takayoshiotake Octave RP2040
  • uChip
  • uGame10
  • uGame22

class busio.I2C(scl: microcontroller.Pin, sda: microcontroller.Pin, *, frequency: int = 100000, timeout: int = 255)

Two wire serial protocol

I2C is a two-wire protocol for communicating between devices. At the physical level it consists of 2 wires: SCL and SDA, the clock and data lines respectively.

See also

Using this class directly requires careful lock management. Instead, use I2CDevice to manage locks.

See also

Using this class to directly read registers requires manual bit unpacking. Instead, use an existing driver or make one with Register data descriptors.

Parameters:

  • scl (Pin) – The clock pin

  • sda (Pin) – The data pin

  • frequency (int) – The clock frequency in Hertz

  • timeout (int) – The maximum clock stretching timeut - (used only for bitbangio.I2C; ignored for busio.I2C)

deinit() → None

Releases control of the underlying hardware so other classes can use it.

__enter__() → I2C

No-op used in Context Managers.

__exit__() → None

Automatically deinitializes the hardware on context exit. See Lifetime and ContextManagers for more info.

scan() → List[int]

Scan all I2C addresses between 0x08 and 0x77 inclusive and return a list of those that respond.

Returns:

List of device ids on the I2C bus

Return type:

list

try_lock() → bool

Attempts to grab the I2C lock. Returns True on success.

Returns:

True when lock has been grabbed

Return type:

bool

unlock() → None

Releases the I2C lock.

readfrom_into(address: int, buffer: circuitpython_typing.WriteableBuffer, *, start: int = 0, end: int = sys.maxsize) → None

Read into buffer from the device selected by address. At least one byte must be read.

If start or end is provided, then the buffer will be sliced as if buffer[start:end] were passed, but without copying the data. The number of bytes read will be the length of buffer[start:end].

Parameters:

  • address (int) – 7-bit device address

  • buffer (WriteableBuffer) – buffer to write into

  • start (int) – beginning of buffer slice

  • end (int) – end of buffer slice; if not specified, use len(buffer)

writeto(address: int, buffer: circuitpython_typing.ReadableBuffer, *, start: int = 0, end: int = sys.maxsize) → None

Write the bytes from buffer to the device selected by address and then transmit a stop bit.

If start or end is provided, then the buffer will be sliced as if buffer[start:end] were passed, but without copying the data. The number of bytes written will be the length of buffer[start:end].

Writing a buffer or slice of length zero is permitted, as it can be used to poll for the existence of a device.

Parameters:

  • address (int) – 7-bit device address

  • buffer (ReadableBuffer) – buffer containing the bytes to write

  • start (int) – beginning of buffer slice

  • end (int) – end of buffer slice; if not specified, use len(buffer)

writeto_then_readfrom(address: int, out_buffer: circuitpython_typing.ReadableBuffer, in_buffer: circuitpython_typing.WriteableBuffer, *, out_start: int = 0, out_end: int = sys.maxsize, in_start: int = 0, in_end: int = sys.maxsize) → None

Write the bytes from out_buffer to the device selected by address, generate no stop bit, generate a repeated start and read into in_buffer. out_buffer and in_buffer can be the same buffer because they are used sequentially.

If out_start or out_end is provided, then the buffer will be sliced as if out_buffer[out_start:out_end] were passed, but without copying the data. The number of bytes written will be the length of out_buffer[start:end].

If in_start or in_end is provided, then the input buffer will be sliced as if in_buffer[in_start:in_end] were passed, The number of bytes read will be the length of out_buffer[in_start:in_end].

Parameters:

  • address (int) – 7-bit device address

  • out_buffer (ReadableBuffer) – buffer containing the bytes to write

  • in_buffer (WriteableBuffer) – buffer to write into

  • out_start (int) – beginning of out_buffer slice

  • out_end (int) – end of out_buffer slice; if not specified, use len(out_buffer)

  • in_start (int) – beginning of in_buffer slice

  • in_end (int) – end of in_buffer slice; if not specified, use len(in_buffer)

class busio.SPI(clock: microcontroller.Pin, MOSI: microcontroller.Pin | None = None, MISO: microcontroller.Pin | None = None, half_duplex: bool = False)

A 3-4 wire serial protocol

SPI is a serial protocol that has exclusive pins for data in and out of the main device. It is typically faster than I2C because a separate pin is used to select a device rather than a transmitted address. This class only manages three of the four SPI lines: clock, MOSI, MISO. Its up to the client to manage the appropriate select line, often abbreviated CS or SS. (This is common because multiple secondaries can share the clock, MOSI and MISO lines and therefore the hardware.)

Available on these boards
  • 01Space 0.42 OLED ESP32C3
  • 0xCB Helios
  • 42. Keebs Frood
  • 8086 Commander
  • @sarfata shIRtty
  • AITHinker ESP32-C3S_Kit
  • AITHinker ESP32-C3S_Kit_2M
  • ARAMCON Badge 2019
  • ARAMCON2 Badge
  • ATMegaZero ESP32-S2
  • Adafruit CLUE nRF52840 Express
  • Adafruit Camera
  • Adafruit Circuit Playground Bluefruit
  • Adafruit Circuit Playground Express 4-H
  • Adafruit CircuitPlayground Express
  • Adafruit CircuitPlayground Express with Crickit libraries
  • Adafruit CircuitPlayground Express with displayio
  • Adafruit EdgeBadge
  • Adafruit Feather Bluefruit Sense
  • Adafruit Feather ESP32 V2
  • Adafruit Feather ESP32-S2 Reverse TFT
  • Adafruit Feather ESP32-S2 TFT
  • Adafruit Feather ESP32-S3 Reverse TFT
  • Adafruit Feather ESP32-S3 TFT
  • Adafruit Feather ESP32S2
  • Adafruit Feather ESP32S3 4MB Flash 2MB PSRAM
  • Adafruit Feather ESP32S3 No PSRAM
  • Adafruit Feather HUZZAH32
  • Adafruit Feather M0 Adalogger
  • Adafruit Feather M0 Basic
  • Adafruit Feather M0 Express
  • Adafruit Feather M0 Express with Crickit libraries
  • Adafruit Feather M0 RFM69
  • Adafruit Feather M0 RFM9x
  • Adafruit Feather M4 CAN
  • Adafruit Feather M4 Express
  • Adafruit Feather MIMXRT1011
  • Adafruit Feather RP2040
  • Adafruit Feather RP2040 CAN
  • Adafruit Feather RP2040 DVI
  • Adafruit Feather RP2040 Prop-Maker
  • Adafruit Feather RP2040 RFM
  • Adafruit Feather RP2040 Scorpio
  • Adafruit Feather RP2040 ThinkInk
  • Adafruit Feather RP2040 USB Host
  • Adafruit Feather STM32F405 Express
  • Adafruit Feather nRF52840 Express
  • Adafruit FunHouse
  • Adafruit Gemma M0
  • Adafruit Gemma M0 PyCon 2018
  • Adafruit Grand Central M4 Express
  • Adafruit HUZZAH32 Breakout
  • Adafruit Hallowing M4 Express
  • Adafruit ItsyBitsy M0 Express
  • Adafruit ItsyBitsy M4 Express
  • Adafruit ItsyBitsy RP2040
  • Adafruit ItsyBitsy nRF52840 Express
  • Adafruit KB2040
  • Adafruit LED Glasses Driver nRF52840
  • Adafruit Macropad RP2040
  • Adafruit MagTag
  • Adafruit Matrix Portal M4
  • Adafruit MatrixPortal S3
  • Adafruit Metro ESP32S2
  • Adafruit Metro ESP32S3
  • Adafruit Metro M0 Express
  • Adafruit Metro M4 Airlift Lite
  • Adafruit Metro M4 Express
  • Adafruit Metro RP2040
  • Adafruit Metro nRF52840 Express
  • Adafruit Monster M4SK
  • Adafruit NeoKey Trinkey M0
  • Adafruit NeoPixel Trinkey M0
  • Adafruit PyGamer
  • Adafruit PyPortal
  • Adafruit PyPortal Pynt
  • Adafruit PyPortal Titano
  • Adafruit PyRuler
  • Adafruit Pybadge
  • Adafruit QT Py ESP32 PICO
  • Adafruit QT Py ESP32-S3 4MB Flash 2MB PSRAM
  • Adafruit QT Py ESP32-S3 no psram
  • Adafruit QT Py ESP32C3
  • Adafruit QT Py ESP32S2
  • Adafruit QT Py M0
  • Adafruit QT Py M0 Haxpress
  • Adafruit QT Py RP2040
  • Adafruit QT2040 Trinkey
  • Adafruit Rotary Trinkey M0
  • Adafruit Slide Trinkey M0
  • Adafruit Trellis M4 Express
  • Adafruit Trinket M0
  • Adafruit-Qualia-S3-RGB666
  • AloriumTech Evo M51
  • Arduino MKR Zero
  • Arduino MKR1300
  • Arduino Nano 33 BLE
  • Arduino Nano 33 IoT
  • Arduino Nano ESP32
  • Arduino Nano RP2040 Connect
  • Arduino Zero
  • Artisense Reference Design RD00
  • AtelierDuMaker nRF52840 Breakout
  • BBQ20KBD
  • BDMICRO VINA-D21
  • BDMICRO VINA-D51
  • BLE-SS dev board Multi Sensor
  • BLOK
  • BPI-Bit-S2
  • BPI-Leaf-S3
  • BPI-PicoW-S3
  • BastBLE
  • BastWiFi
  • Bee-Data-Logger
  • Bee-Motion-S3
  • Bee-S3
  • BlueMicro833
  • BlueMicro840
  • COSMO-Pico
  • CP Sapling M0
  • CP Sapling M0 w/ SPI Flash
  • CP32-M4
  • CRCibernetica IdeaBoard
  • Capable Robot Programmable USB Hub
  • Cedar Grove StringCar M0 Express
  • Challenger NB RP2040 WiFi
  • Challenger RP2040 LTE
  • Challenger RP2040 LoRa
  • Challenger RP2040 SD/RTC
  • Challenger RP2040 SubGHz
  • Challenger RP2040 WiFi
  • Challenger RP2040 WiFi/BLE
  • Circuit Playground Express Digi-Key PyCon 2019
  • CircuitBrains Basic
  • CircuitBrains Deluxe
  • CrumpS2
  • Cytron Maker Feather AIoT S3
  • Cytron Maker Nano RP2040
  • Cytron Maker Pi RP2040
  • Cytron Maker Zero SAMD21
  • DFRobot Beetle ESP32-C3
  • Datanoise PicoADK
  • Deneyap Kart
  • Deneyap Kart 1A
  • Deneyap Kart 1A v2
  • Deneyap Kart G
  • Deneyap Mini
  • Deneyap Mini v2
  • Diodes Delight Piunora
  • DynOSSAT-EDU-EPS
  • DynOSSAT-EDU-OBC
  • DynaLoRa_USB
  • E-Fidget
  • ELECFREAKS PICO:ED
  • ES3ink
  • ESP 12k NodeMCU
  • ESP32 Devkit V1
  • ESP32-C3-DevKitM-1
  • ESP32-C6-DevKitC-1-N8
  • ESP32-C6-DevKitM-1
  • ESP32-H2-DevKitM-1
  • ESP32-S2-DevKitC-1-N4
  • ESP32-S2-DevKitC-1-N4R2
  • ESP32-S2-DevKitC-1-N8R2
  • ESP32-S3-Box-2.5
  • ESP32-S3-Box-Lite
  • ESP32-S3-DevKitC-1-N32R8
  • ESP32-S3-DevKitC-1-N8
  • ESP32-S3-DevKitC-1-N8R2
  • ESP32-S3-DevKitC-1-N8R8
  • ESP32-S3-DevKitC-1-N8R8-with-HACKTABLET
  • ESP32-S3-DevKitM-1-N8
  • ESP32-S3-EYE
  • ESP32-S3-USB-OTG-N8
  • Electrolama minik
  • Electronic Cats Bast Pro Mini M0
  • Electronic Cats CatWAN USBStick
  • Electronic Cats Hunter Cat NFC
  • Electronic Cats NFC Copy Cat
  • Electronut Labs Blip
  • Electronut Labs Papyr
  • EncoderPad RP2040
  • Escornabot Makech
  • Espressif ESP32-EYE
  • Espressif ESP32-LyraT
  • Espressif-ESP32-S3-LCD-EV-Board
  • Espruino Bangle.js 2
  • Espruino Pico
  • Espruino Wifi
  • Feather MIMXRT1011
  • Feather MIMXRT1062
  • FeatherS2
  • FeatherS2 Neo
  • FeatherS2 PreRelease
  • FeatherS3
  • Fig Pi
  • Fluff M0
  • Fomu
  • Franzininho WIFI w/Wroom
  • Franzininho WIFI w/Wrover
  • Gravitech Cucumber M
  • Gravitech Cucumber MS
  • Gravitech Cucumber R
  • Gravitech Cucumber RS
  • HMI-DevKit-1.1
  • Hack Club Sprig
  • Hacked Feather M0 Express with 8Mbyte SPI flash
  • HalloWing M0 Express
  • Hardkernel Odroid Go
  • HexKyS2
  • HiiBot BlueFi
  • IMXRT1010-EVK
  • IMXRT1015-EVK
  • IkigaiSense Vita nRF52840
  • IoTs2
  • J&J Studios datum-Distance
  • J&J Studios datum-IMU
  • J&J Studios datum-Light
  • J&J Studios datum-Weather
  • Kaluga 1
  • LILYGO T-DISPLAY
  • LILYGO TEMBED ESP32S3
  • LILYGO TTGO T-01C3
  • LILYGO TTGO T-DISPLAY v1.1
  • LILYGO TTGO T-OI PLUS
  • LILYGO TTGO T8 ESP32-S2
  • LILYGO TTGO T8 ESP32-S2 w/Display
  • LOLIN S3 16MB Flash 8MB PSRAM
  • LOLIN S3 MINI 4MB Flash 2MB PSRAM
  • Lilygo T-watch 2020 V3
  • LoC BeR M4 base board
  • Luatos Core-ESP32C3
  • M5STACK STAMP-C3
  • M5Stack Atom Echo
  • M5Stack Atom Lite
  • M5Stack Atom Matrix
  • M5Stack Atom U
  • M5Stack AtomS3 Lite
  • M5Stack AtomS3U
  • M5Stack Core Basic
  • M5Stack Core Fire
  • M5Stack Core2
  • M5Stack M5Paper
  • M5Stack Stick C
  • M5Stack Stick C Plus
  • M5Stack Timer Camera X
  • MDBT50Q-DB-40
  • MDBT50Q-RX Dongle
  • MEOWBIT
  • MORPHEANS MorphESP-240
  • Maker badge by Czech maker
  • MakerDiary nRF52840 MDK
  • MakerDiary nRF52840 MDK USB Dongle
  • MakerFabs-ESP32-S3-Parallel-TFT-With-Touch-7inch
  • Makerdiary M60 Keyboard
  • Makerdiary Pitaya Go
  • Makerdiary nRF52840 Connect Kit
  • Makerdiary nRF52840 M.2 Developer Kit
  • Melopero Shake RP2040
  • Meow Meow
  • Metro MIMXRT1011
  • MicroDev microC3
  • MicroDev microS2
  • Mini SAM M4
  • MixGo CE
  • NUCLEO F446RE
  • NUCLEO STM32F746
  • NUCLEO STM32F767
  • NUCLEO STM32H743
  • NanoS3
  • Neuron
  • OPENMV-H7 R1
  • Oak Dev Tech BREAD2040
  • Oak Dev Tech Cast-Away RP2040
  • Oak Dev Tech PixelWing ESP32S2
  • Open Hardware Summit 2020 Badge
  • PCA10056 nRF52840-DK
  • PCA10059 nRF52840 Dongle
  • PCA10100 nRF52833 DK
  • PYB LR Nano V2
  • Pajenicko PicoPad
  • Particle Argon
  • Particle Boron
  • Particle Xenon
  • PewPew 10.2
  • PewPew LCD
  • PewPew M4
  • PicoPlanet
  • PillBug
  • Pimoroni Badger 2040
  • Pimoroni Badger 2040 W
  • Pimoroni Inky Frame 5.7
  • Pimoroni Interstate 75
  • Pimoroni Keybow 2040
  • Pimoroni Motor 2040
  • Pimoroni PGA2040
  • Pimoroni Pico DV Base W
  • Pimoroni Pico LiPo (16MB)
  • Pimoroni Pico LiPo (4MB)
  • Pimoroni Pico dv Base
  • Pimoroni PicoSystem
  • Pimoroni Plasma 2040
  • Pimoroni Plasma 2040W
  • Pimoroni Servo 2040
  • Pimoroni Tiny 2040 (2MB)
  • Pimoroni Tiny 2040 (8MB)
  • ProS3
  • PyCubedv04
  • PyCubedv04-MRAM
  • PyCubedv05
  • PyCubedv05-MRAM
  • PyKey 18 Numpad
  • PyKey 44 Ergo
  • PyKey 60
  • PyKey 87 TKL
  • PyboardV1_1
  • RP2.65-F
  • RP2040 Stamp
  • Raspberry Pi 4B
  • Raspberry Pi Compute Module 4
  • Raspberry Pi Compute Module 4 IO Board
  • Raspberry Pi Pico
  • Raspberry Pi Pico W
  • Raspberry Pi Zero
  • Raspberry Pi Zero 2W
  • Raspberry Pi Zero W
  • Robo HAT MM1 M4
  • S2Mini
  • S2Pico
  • SAM E54 Xplained Pro
  • SAM32v26
  • SPRESENSE
  • SSCI ISP1807 Dev Board
  • SSCI ISP1807 Micro Board
  • ST STM32F746G Discovery
  • STM32F411E_DISCO
  • STM32F412G_DISCO
  • STM32F4_DISCO
  • Saola 1 w/Wroom
  • Saola 1 w/Wrover
  • Seeed Studio XIAO ESP32C3
  • Seeed XIAO nRF52840 Sense
  • Seeeduino Wio Terminal
  • Seeeduino XIAO
  • Seeeduino XIAO KB
  • Seeeduino XIAO RP2040
  • Serpente
  • SiLabs xG24 Dev Kit
  • SiLabs xG24 Explorer Kit
  • Silicognition LLC M4-Shim
  • Silicognition LLC RP2040-Shim
  • Simmel
  • SparkFun LUMIDrive
  • SparkFun MicroMod RP2040 Processor
  • SparkFun MicroMod SAMD51 Processor
  • SparkFun MicroMod nRF52840 Processor
  • SparkFun Pro Micro RP2040
  • SparkFun Pro nRF52840 Mini
  • SparkFun Qwiic Micro
  • SparkFun RedBoard Turbo
  • SparkFun SAMD21 Dev Breakout
  • SparkFun SAMD21 Mini Breakout
  • SparkFun STM32 MicroMod Processor
  • SparkFun Teensy MicroMod Processor
  • SparkFun Thing Plus - RP2040
  • SparkFun Thing Plus - SAMD51
  • SparkFun Thing Plus - STM32
  • Sparkfun Thing Plus MGM240P
  • Sprite_v2b
  • StackRduino M0 PRO
  • Swan R5
  • TG-Boards' Datalore IP M4
  • TG-Watch
  • THUNDERPACK_v11
  • THUNDERPACK_v12
  • TTGO T8 ESP32-S2-WROOM
  • Targett Module Clip w/Wroom
  • Targett Module Clip w/Wrover
  • Teensy 4.0
  • Teensy 4.1
  • Teknikio Bluebird
  • The Open Book Feather
  • TinkeringTech ScoutMakes Azul
  • TinyPICO
  • TinyPICO Nano
  • TinyS2
  • TinyS3
  • Trinket M0 Haxpress
  • UARTLogger II
  • VCC-GND Studio YD RP2040
  • VCC-GND YD-ESP32-S3 (N16R8)
  • VCC-GND YD-ESP32-S3 (N8R8)
  • W5100S-EVB-Pico
  • W5500-EVB-Pico
  • WarmBit BluePixel nRF52840
  • Waveshare ESP32-S2-Pico
  • Waveshare ESP32-S2-Pico-LCD
  • Waveshare ESP32-S3-Pico
  • Waveshare RP2040-LCD-0.96
  • Waveshare RP2040-LCD-1.28
  • Waveshare RP2040-Plus (16MB)
  • Waveshare RP2040-Plus (4MB)
  • Waveshare RP2040-Zero
  • WeAct Studio Pico
  • WeAct Studio Pico 16MB
  • Wemos Lolin C3 Mini" // from Wemos MP
  • Wemos Lolin C3 Pico" // from Wemos MP
  • Winterbloom Big Honking Button
  • Winterbloom Sol
  • XinaBox CC03
  • XinaBox CS11
  • iLabs Challenger 840
  • iMX RT 1020 EVK
  • iMX RT 1040 EVK
  • iMX RT 1050 EVKB
  • iMX RT 1060 EVK
  • iMX RT 1060 EVKB
  • keithp.com snekboard
  • micro:bit v2
  • nanoESP32-S2 w/Wrover
  • nanoESP32-S2 w/Wroom
  • ndGarage[n°] Bit6: FeatherSnow-v2
  • ndGarage[n°]Bit6:FeatherSnow
  • nice!nano
  • nullbits Bit-C PRO
  • senseBox MCU
  • splitkb.com Liatris
  • stm32f411ce-blackpill
  • stm32f411ce-blackpill-with-flash
  • takayoshiotake Octave RP2040
  • uChip
  • uGame10
  • uGame22

Construct an SPI object on the given pins.

Note

The SPI peripherals allocated in order of desirability, if possible, such as highest speed and not shared use first. For instance, on the nRF52840, there is a single 32MHz SPI peripheral, and multiple 8MHz peripherals, some of which may also be used for I2C. The 32MHz SPI peripheral is returned first, then the exclusive 8MHz SPI peripheral, and finally the shared 8MHz peripherals.

See also

Using this class directly requires careful lock management. Instead, use SPIDevice to manage locks.

See also

Using this class to directly read registers requires manual bit unpacking. Instead, use an existing driver or make one with Register data descriptors.

Parameters:

  • clock (Pin) – the pin to use for the clock.

  • MOSI (Pin) – the Main Out Selected In pin.

  • MISO (Pin) – the Main In Selected Out pin.

  • half_duplex (bool) – True when MOSI is used for bidirectional data. False when SPI is full-duplex or simplex.

Limitations: half_duplex is available only on STM; other chips do not have the hardware support.

frequency: int

The actual SPI bus frequency. This may not match the frequency requested due to internal limitations.

deinit() → None

Turn off the SPI bus.

__enter__() → SPI

No-op used by Context Managers. Provided by context manager helper.

__exit__() → None

Automatically deinitializes the hardware when exiting a context. See Lifetime and ContextManagers for more info.

configure(*, baudrate: int = 100000, polarity: int = 0, phase: int = 0, bits: int = 8) → None

Configures the SPI bus. The SPI object must be locked.

Parameters:

  • baudrate (int) – the desired clock rate in Hertz. The actual clock rate may be higher or lower due to the granularity of available clock settings. Check the frequency attribute for the actual clock rate.

  • polarity (int) – the base state of the clock line (0 or 1)

  • phase (int) – the edge of the clock that data is captured. First (0) or second (1). Rising or falling depends on clock polarity.

  • bits (int) – the number of bits per word

Note

On the SAMD21, it is possible to set the baudrate to 24 MHz, but that speed is not guaranteed to work. 12 MHz is the next available lower speed, and is within spec for the SAMD21.

Note

On the nRF52840, these baudrates are available: 125kHz, 250kHz, 1MHz, 2MHz, 4MHz, and 8MHz. If you pick a a baudrate other than one of these, the nearest lower baudrate will be chosen, with a minimum of 125kHz. Two SPI objects may be created, except on the Circuit Playground Bluefruit, which allows only one (to allow for an additional I2C object).

try_lock() → bool

Attempts to grab the SPI lock. Returns True on success.

Returns:

True when lock has been grabbed

Return type:

bool

unlock() → None

Releases the SPI lock.

write(buffer: circuitpython_typing.ReadableBuffer, *, start: int = 0, end: int = sys.maxsize) → None

Write the data contained in buffer. The SPI object must be locked. If the buffer is empty, nothing happens.

If start or end is provided, then the buffer will be sliced as if buffer[start:end] were passed, but without copying the data. The number of bytes written will be the length of buffer[start:end].

Parameters:

  • buffer (ReadableBuffer) – write out bytes from this buffer

  • start (int) – beginning of buffer slice

  • end (int) – end of buffer slice; if not specified, use len(buffer)

readinto(buffer: circuitpython_typing.WriteableBuffer, *, start: int = 0, end: int = sys.maxsize, write_value: int = 0) → None

Read into buffer while writing write_value for each byte read. The SPI object must be locked. If the number of bytes to read is 0, nothing happens.

If start or end is provided, then the buffer will be sliced as if buffer[start:end] were passed. The number of bytes read will be the length of buffer[start:end].

Parameters:

  • buffer (WriteableBuffer) – read bytes into this buffer

  • start (int) – beginning of buffer slice

  • end (int) – end of buffer slice; if not specified, it will be the equivalent value of len(buffer) and for any value provided it will take the value of min(end, len(buffer))

  • write_value (int) – value to write while reading

write_readinto(out_buffer: circuitpython_typing.ReadableBuffer, in_buffer: circuitpython_typing.WriteableBuffer, *, out_start: int = 0, out_end: int = sys.maxsize, in_start: int = 0, in_end: int = sys.maxsize) → None

Write out the data in out_buffer while simultaneously reading data into in_buffer. The SPI object must be locked.

If out_start or out_end is provided, then the buffer will be sliced as if out_buffer[out_start:out_end] were passed, but without copying the data. The number of bytes written will be the length of out_buffer[out_start:out_end].

If in_start or in_end is provided, then the input buffer will be sliced as if in_buffer[in_start:in_end] were passed, The number of bytes read will be the length of out_buffer[in_start:in_end].

The lengths of the slices defined by out_buffer[out_start:out_end] and in_buffer[in_start:in_end] must be equal. If buffer slice lengths are both 0, nothing happens.

Parameters:

  • out_buffer (ReadableBuffer) – write out bytes from this buffer

  • in_buffer (WriteableBuffer) – read bytes into this buffer

  • out_start (int) – beginning of out_buffer slice

  • out_end (int) – end of out_buffer slice; if not specified, use len(out_buffer)

  • in_start (int) – beginning of in_buffer slice

  • in_end (int) – end of in_buffer slice; if not specified, use len(in_buffer)

class busio.UART(tx: microcontroller.Pin | None = None, rx: microcontroller.Pin | None = None, *, rts: microcontroller.Pin | None = None, cts: microcontroller.Pin | None = None, rs485_dir: microcontroller.Pin | None = None, rs485_invert: bool = False, baudrate: int = 9600, bits: int = 8, parity: Parity | None = None, stop: int = 1, timeout: float = 1, receiver_buffer_size: int = 64)

A bidirectional serial protocol

Available on these boards
  • 01Space 0.42 OLED ESP32C3
  • 0xCB Helios
  • 42. Keebs Frood
  • 8086 Commander
  • @sarfata shIRtty
  • AITHinker ESP32-C3S_Kit
  • AITHinker ESP32-C3S_Kit_2M
  • ARAMCON Badge 2019
  • ARAMCON2 Badge
  • ATMegaZero ESP32-S2
  • Adafruit BLM Badge
  • Adafruit CLUE nRF52840 Express
  • Adafruit Camera
  • Adafruit Circuit Playground Bluefruit
  • Adafruit Circuit Playground Express 4-H
  • Adafruit CircuitPlayground Express
  • Adafruit CircuitPlayground Express with Crickit libraries
  • Adafruit CircuitPlayground Express with displayio
  • Adafruit EdgeBadge
  • Adafruit Feather Bluefruit Sense
  • Adafruit Feather ESP32 V2
  • Adafruit Feather ESP32-S2 Reverse TFT
  • Adafruit Feather ESP32-S2 TFT
  • Adafruit Feather ESP32-S3 Reverse TFT
  • Adafruit Feather ESP32-S3 TFT
  • Adafruit Feather ESP32S2
  • Adafruit Feather ESP32S3 4MB Flash 2MB PSRAM
  • Adafruit Feather ESP32S3 No PSRAM
  • Adafruit Feather HUZZAH32
  • Adafruit Feather M0 Adalogger
  • Adafruit Feather M0 Basic
  • Adafruit Feather M0 Express
  • Adafruit Feather M0 Express with Crickit libraries
  • Adafruit Feather M0 RFM69
  • Adafruit Feather M0 RFM9x
  • Adafruit Feather M4 CAN
  • Adafruit Feather M4 Express
  • Adafruit Feather MIMXRT1011
  • Adafruit Feather RP2040
  • Adafruit Feather RP2040 CAN
  • Adafruit Feather RP2040 DVI
  • Adafruit Feather RP2040 Prop-Maker
  • Adafruit Feather RP2040 RFM
  • Adafruit Feather RP2040 Scorpio
  • Adafruit Feather RP2040 ThinkInk
  • Adafruit Feather RP2040 USB Host
  • Adafruit Feather STM32F405 Express
  • Adafruit Feather nRF52840 Express
  • Adafruit FunHouse
  • Adafruit Gemma M0
  • Adafruit Gemma M0 PyCon 2018
  • Adafruit Grand Central M4 Express
  • Adafruit HUZZAH32 Breakout
  • Adafruit Hallowing M4 Express
  • Adafruit ItsyBitsy M0 Express
  • Adafruit ItsyBitsy M4 Express
  • Adafruit ItsyBitsy RP2040
  • Adafruit ItsyBitsy nRF52840 Express
  • Adafruit KB2040
  • Adafruit LED Glasses Driver nRF52840
  • Adafruit Macropad RP2040
  • Adafruit MagTag
  • Adafruit Matrix Portal M4
  • Adafruit MatrixPortal S3
  • Adafruit Metro ESP32S2
  • Adafruit Metro ESP32S3
  • Adafruit Metro M0 Express
  • Adafruit Metro M4 Airlift Lite
  • Adafruit Metro M4 Express
  • Adafruit Metro RP2040
  • Adafruit Metro nRF52840 Express
  • Adafruit Monster M4SK
  • Adafruit NeoKey Trinkey M0
  • Adafruit NeoPixel Trinkey M0
  • Adafruit PyGamer
  • Adafruit PyPortal
  • Adafruit PyPortal Pynt
  • Adafruit PyPortal Titano
  • Adafruit PyRuler
  • Adafruit Pybadge
  • Adafruit QT Py ESP32 PICO
  • Adafruit QT Py ESP32-S3 4MB Flash 2MB PSRAM
  • Adafruit QT Py ESP32-S3 no psram
  • Adafruit QT Py ESP32C3
  • Adafruit QT Py ESP32S2
  • Adafruit QT Py M0
  • Adafruit QT Py M0 Haxpress
  • Adafruit QT Py RP2040
  • Adafruit QT2040 Trinkey
  • Adafruit Rotary Trinkey M0
  • Adafruit Slide Trinkey M0
  • Adafruit Trellis M4 Express
  • Adafruit Trinket M0
  • Adafruit-Qualia-S3-RGB666
  • AloriumTech Evo M51
  • Arduino MKR Zero
  • Arduino MKR1300
  • Arduino Nano 33 BLE
  • Arduino Nano 33 IoT
  • Arduino Nano ESP32
  • Arduino Nano RP2040 Connect
  • Arduino Zero
  • Artisense Reference Design RD00
  • AtelierDuMaker nRF52840 Breakout
  • BBQ20KBD
  • BDMICRO VINA-D21
  • BDMICRO VINA-D51
  • BLE-SS dev board Multi Sensor
  • BLOK
  • BPI-Bit-S2
  • BPI-Leaf-S3
  • BPI-PicoW-S3
  • BastBLE
  • BastWiFi
  • Bee-Data-Logger
  • Bee-Motion-S3
  • Bee-S3
  • BlueMicro833
  • BlueMicro840
  • COSMO-Pico
  • CP Sapling M0
  • CP Sapling M0 w/ SPI Flash
  • CP32-M4
  • CRCibernetica IdeaBoard
  • Capable Robot Programmable USB Hub
  • Cedar Grove StringCar M0 Express
  • Challenger NB RP2040 WiFi
  • Challenger RP2040 LTE
  • Challenger RP2040 LoRa
  • Challenger RP2040 SD/RTC
  • Challenger RP2040 SubGHz
  • Challenger RP2040 WiFi
  • Challenger RP2040 WiFi/BLE
  • Circuit Playground Express Digi-Key PyCon 2019
  • CircuitBrains Basic
  • CircuitBrains Deluxe
  • CrumpS2
  • Cytron Maker Feather AIoT S3
  • Cytron Maker Nano RP2040
  • Cytron Maker Pi RP2040
  • Cytron Maker Zero SAMD21
  • DFRobot Beetle ESP32-C3
  • Datanoise PicoADK
  • Deneyap Kart
  • Deneyap Kart 1A
  • Deneyap Kart 1A v2
  • Deneyap Kart G
  • Deneyap Mini
  • Deneyap Mini v2
  • Diodes Delight Piunora
  • DynOSSAT-EDU-EPS
  • DynOSSAT-EDU-OBC
  • DynaLoRa_USB
  • E-Fidget
  • ELECFREAKS PICO:ED
  • ES3ink
  • ESP 12k NodeMCU
  • ESP32 Devkit V1
  • ESP32-C3-DevKitM-1
  • ESP32-C6-DevKitC-1-N8
  • ESP32-C6-DevKitM-1
  • ESP32-H2-DevKitM-1
  • ESP32-S2-DevKitC-1-N4
  • ESP32-S2-DevKitC-1-N4R2
  • ESP32-S2-DevKitC-1-N8R2
  • ESP32-S3-Box-2.5
  • ESP32-S3-Box-Lite
  • ESP32-S3-DevKitC-1-N32R8
  • ESP32-S3-DevKitC-1-N8
  • ESP32-S3-DevKitC-1-N8R2
  • ESP32-S3-DevKitC-1-N8R8
  • ESP32-S3-DevKitC-1-N8R8-with-HACKTABLET
  • ESP32-S3-DevKitM-1-N8
  • ESP32-S3-EYE
  • ESP32-S3-USB-OTG-N8
  • Electrolama minik
  • Electronic Cats Bast Pro Mini M0
  • Electronic Cats CatWAN USBStick
  • Electronic Cats Hunter Cat NFC
  • Electronic Cats NFC Copy Cat
  • Electronut Labs Blip
  • Electronut Labs Papyr
  • EncoderPad RP2040
  • Escornabot Makech
  • Espressif ESP32-EYE
  • Espressif ESP32-LyraT
  • Espressif-ESP32-S3-LCD-EV-Board
  • Espruino Bangle.js 2
  • Espruino Pico
  • Espruino Wifi
  • Feather MIMXRT1011
  • Feather MIMXRT1062
  • FeatherS2
  • FeatherS2 Neo
  • FeatherS2 PreRelease
  • FeatherS3
  • Fig Pi
  • Fluff M0
  • Fomu
  • Franzininho WIFI w/Wroom
  • Franzininho WIFI w/Wrover
  • Gravitech Cucumber M
  • Gravitech Cucumber MS
  • Gravitech Cucumber R
  • Gravitech Cucumber RS
  • HMI-DevKit-1.1
  • Hack Club Sprig
  • Hacked Feather M0 Express with 8Mbyte SPI flash
  • HalloWing M0 Express
  • Hardkernel Odroid Go
  • HexKyS2
  • HiiBot BlueFi
  • IMXRT1010-EVK
  • IMXRT1015-EVK
  • IkigaiSense Vita nRF52840
  • IoTs2
  • J&J Studios datum-Distance
  • J&J Studios datum-IMU
  • J&J Studios datum-Light
  • J&J Studios datum-Weather
  • Kaluga 1
  • LILYGO T-DISPLAY
  • LILYGO TEMBED ESP32S3
  • LILYGO TTGO T-01C3
  • LILYGO TTGO T-DISPLAY v1.1
  • LILYGO TTGO T-OI PLUS
  • LILYGO TTGO T8 ESP32-S2
  • LILYGO TTGO T8 ESP32-S2 w/Display
  • LOLIN S3 16MB Flash 8MB PSRAM
  • LOLIN S3 MINI 4MB Flash 2MB PSRAM
  • Lilygo T-watch 2020 V3
  • LoC BeR M4 base board
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A common bidirectional serial protocol that uses an an agreed upon speed rather than a shared clock line.

Parameters:

  • tx (Pin) – the pin to transmit with, or None if this UART is receive-only.

  • rx (Pin) – the pin to receive on, or None if this UART is transmit-only.

  • rts (Pin) – the pin for rts, or None if rts not in use.

  • cts (Pin) – the pin for cts, or None if cts not in use.

  • rs485_dir (Pin) – the output pin for rs485 direction setting, or None if rs485 not in use.

  • rs485_invert (bool) – rs485_dir pin active high when set. Active low otherwise.

  • baudrate (int) – the transmit and receive speed.

  • bits (int) – the number of bits per byte, 5 to 9.

  • parity (Parity) – the parity used for error checking.

  • stop (int) – the number of stop bits, 1 or 2.

  • timeout (float) – the timeout in seconds to wait for the first character and between subsequent characters when reading. Raises ValueError if timeout >100 seconds.

  • receiver_buffer_size (int) – the character length of the read buffer (0 to disable). (When a character is 9 bits the buffer will be 2 * receiver_buffer_size bytes.)

tx and rx cannot both be None.

New in CircuitPython 4.0: timeout has incompatibly changed units from milliseconds to seconds. The new upper limit on timeout is meant to catch mistaken use of milliseconds.

Limitations: RS485 is not supported on SAMD, nRF, Broadcom, Spresense, or STM. On i.MX and Raspberry Pi RP2040, RS485 support is implemented in software: The timing for the rs485_dir pin signal is done on a best-effort basis, and may not meet RS485 specifications intermittently.

baudrate: int

The current baudrate.

in_waiting: int

The number of bytes in the input buffer, available to be read

timeout: float

The current timeout, in seconds (float).

deinit() → None

Deinitialises the UART and releases any hardware resources for reuse.

__enter__() → UART

No-op used by Context Managers.

__exit__() → None

Automatically deinitializes the hardware when exiting a context. See Lifetime and ContextManagers for more info.

read(nbytes: int | None = None) → bytes | None

Read bytes. If nbytes is specified then read at most that many bytes. Otherwise, read everything that arrives until the connection times out. Providing the number of bytes expected is highly recommended because it will be faster. If no bytes are read, return None.

Note

When no bytes are read due to a timeout, this function returns None. This matches the behavior of io.RawIOBase.read in Python 3, but differs from pyserial which returns b'' in that situation.

Returns:

Data read

Return type:

bytes or None

readinto(buf: circuitpython_typing.WriteableBuffer) → int | None

Read bytes into the buf. Read at most len(buf) bytes.

Returns:

number of bytes read and stored into buf

Return type:

int or None (on a non-blocking error)

New in CircuitPython 4.0: No length parameter is permitted.

readline() → bytes

Read a line, ending in a newline character, or return None if a timeout occurs sooner, or return everything readable if no newline is found and timeout=0

Returns:

the line read

Return type:

bytes or None

write(buf: circuitpython_typing.ReadableBuffer) → int | None

Write the buffer of bytes to the bus.

New in CircuitPython 4.0: buf must be bytes, not a string.

return:

the number of bytes written

rtype:

int or None

reset_input_buffer() → None

Discard any unread characters in the input buffer.

class busio.Parity

Enum-like class to define the parity used to verify correct data transfer.

ODD: int

Total number of ones should be odd.

EVEN: int

Total number of ones should be even.