ps2io – Support for PS/2 protocol

The ps2io module contains classes to provide PS/2 communication.


This module is not available in some SAMD21 builds. See the Module Support Matrix - Which Modules Are Available on Which Boards for more info.

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.

Available on these boards
  • ATMegaZero ESP32-S2
  • Adafruit Camera
  • Adafruit EdgeBadge
  • Adafruit Feather ESP32-S2 TFT
  • Adafruit Feather ESP32S2
  • Adafruit Feather ESP32S3 No PSRAM
  • Adafruit Feather M4 CAN
  • Adafruit Feather M4 Express
  • Adafruit FunHouse
  • Adafruit Grand Central M4 Express
  • Adafruit Hallowing M4 Express
  • Adafruit ItsyBitsy M4 Express
  • Adafruit MagTag
  • Adafruit Matrix Portal M4
  • Adafruit Metro ESP32S2
  • Adafruit Metro M4 Airlift Lite
  • Adafruit Metro M4 Express
  • Adafruit Monster M4SK
  • Adafruit PyGamer
  • Adafruit PyPortal
  • Adafruit PyPortal Pynt
  • Adafruit PyPortal Titano
  • Adafruit Pybadge
  • Adafruit QT Py ESP32-S3 no psram
  • Adafruit QT Py ESP32S2
  • Adafruit Trellis M4 Express
  • AloriumTech Evo M51
  • Artisense Reference Design RD00
  • BastWiFi
  • CP32-M4
  • Capable Robot Programmable USB Hub
  • CircuitBrains Deluxe
  • CrumpS2
  • Cytron Maker Feather AIoT S3
  • ESP 12k NodeMCU
  • ESP32-S2-DevKitC-1-N4
  • ESP32-S2-DevKitC-1-N4R2
  • ESP32-S3-Box-2.5
  • ESP32-S3-DevKitC-1-N8
  • ESP32-S3-DevKitC-1-N8R2
  • ESP32-S3-DevKitC-1-N8R8
  • ESP32-S3-DevKitM-1-N8
  • ESP32-S3-USB-OTG-N8
  • Feather ESP32S2 without PSRAM
  • FeatherS2
  • FeatherS2 Neo
  • FeatherS2 PreRelease
  • FeatherS3
  • Franzininho WIFI w/Wroom
  • Franzininho WIFI w/Wrover
  • Gravitech Cucumber M
  • Gravitech Cucumber MS
  • Gravitech Cucumber R
  • Gravitech Cucumber RS
  • HMI-DevKit-1.1
  • HexKyS2
  • IoTs2
  • Kaluga 1
  • LILYGO TTGO T8 ESP32-S2 w/Display
  • LoC BeR M4 base board
  • MORPHEANS MorphESP-240
  • MicroDev microS2
  • Mini SAM M4
  • Oak Dev Tech PixelWing ESP32S2
  • ProS3
  • Robo HAT MM1 M4
  • S2Mini
  • S2Pico
  • SAM32v26
  • Saola 1 w/Wroom
  • Saola 1 w/Wrover
  • Seeeduino Wio Terminal
  • Silicognition LLC M4-Shim
  • SparkFun MicroMod SAMD51 Processor
  • SparkFun Thing Plus - SAMD51
  • TG-Boards' Datalore IP M4
  • Targett Module Clip w/Wroom
  • Targett Module Clip w/Wrover
  • The Open Book Feather
  • TinyS2
  • TinyS3
  • UARTLogger II
  • nanoESP32-S2 w/Wrover
  • nanoESP32-S2 w/Wroom

class ps2io.Ps2(data_pin: microcontroller.Pin, clock_pin: microcontroller.Pin)

Communicate with a PS/2 keyboard or mouse

Ps2 implements the PS/2 keyboard/mouse serial protocol, used in legacy devices. It is similar to UART but there are only two lines (Data and Clock). PS/2 devices are 5V, so bidirectional level converters must be used to connect the I/O lines to pins of 3.3V boards.

Create a Ps2 object associated with the given pins.

  • data_pin (Pin) – Pin tied to data wire.

  • clock_pin (Pin) – Pin tied to clock wire. This pin must support interrupts.

Read one byte from PS/2 keyboard and turn on Scroll Lock LED:

import ps2io
import board

kbd = ps2io.Ps2(board.D10, board.D11)

while len(kbd) == 0:

deinit() None

Deinitialises the Ps2 and releases any hardware resources for reuse.

__enter__() Ps2

No-op used by Context Managers.

__exit__() None

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

popleft() int

Removes and returns the oldest received byte. When buffer is empty, raises an IndexError exception.

sendcmd(byte: int) int

Sends a command byte to PS/2. Returns the response byte, typically the general ack value (0xFA). Some commands return additional data which is available through popleft().

Raises a RuntimeError in case of failure. The root cause can be found by calling clear_errors(). It is advisable to call clear_errors() before sendcmd() to flush any previous errors.


byte (int) – byte value of the command

clear_errors() None

Returns and clears a bitmap with latest recorded communication errors.

Reception errors (arise asynchronously, as data is received):

0x01: start bit not 0

0x02: timeout

0x04: parity bit error

0x08: stop bit not 1

0x10: buffer overflow, newest data discarded

Transmission errors (can only arise in the course of sendcmd()):

0x100: clock pin didn’t go to LO in time

0x200: clock pin didn’t go to HI in time

0x400: data pin didn’t ACK

0x800: clock pin didn’t ACK

0x1000: device didn’t respond to RTS

0x2000: device didn’t send a response byte in time

__bool__() bool
__len__() int

Returns the number of received bytes in buffer, available to popleft().