adafruit_fram

CircuitPython/Python library to support the I2C and SPI FRAM Breakouts.

  • Author(s): Michael Schroeder

Implementation Notes

Hardware:

Software and Dependencies:

class adafruit_fram.FRAM(max_size: int, write_protect: bool = False, wp_pin: DigitalInOut | None = None)

Driver base for the FRAM Breakout.

Parameters:

  • max_size (int) – The maximum size of the EEPROM

  • write_protect (bool) – Turns on/off initial write protection

  • wp_pin (DigitalInOut) – (Optional) Physical pin connected to the WP breakout pin. Must be a DigitalInOut object.

__getitem__(address: int | slice) → bytearray

Read the value at the given index, or values in a slice.

# read single index
fram[0]

# read values 0 thru 9 with a slice
fram[0:9]
__len__() → int

The size of the current FRAM chip. This is one more than the highest address location that can be read or written to.

fram = adafruit_fram.FRAM_xxx() # xxx = 'I2C' or 'SPI'

# size returned by len()
len(fram)

# can be used with range
for i in range(0, len(fram))
__setitem__(address: int | slice, value: int | Sequence[int])

Write the value at the given starting index.

# write single index
fram[0] = 1

# write values 0 thru 4 with a list
fram[0:4] = [0,1,2,3]
property write_protected: bool

The status of write protection. Default value on initialization is False.

When a WP pin is supplied during initialization, or using write_protect_pin, the status is tied to that pin and enables hardware-level protection.

When no WP pin is supplied, protection is only at the software level in this library.

property write_wraparound: bool

Determines if sequential writes will wrapaound highest memory address (len(FRAM) - 1) address. If False, and a requested write will extend beyond the maximum size, an exception is raised.

class adafruit_fram.FRAM_I2C(i2c_bus: I2C, address: int = 80, write_protect: bool = False, wp_pin: DigitalInOut | None = None)

I2C class for FRAM.

Parameters:

  • i2c_bus (I2C) – The I2C bus the FRAM is connected to.

  • address (int) – I2C address of FRAM. Default address is 0x50.

  • write_protect (bool) – Turns on/off initial write protection. Default is False.

  • wp_pin – (Optional) Physical pin connected to the WP breakout pin. Must be a digitalio.DigitalInOut object.

property write_protected: bool

The status of write protection. Default value on initialization is False.

When a WP pin is supplied during initialization, or using write_protect_pin, the status is tied to that pin and enables hardware-level protection.

When no WP pin is supplied, protection is only at the software level in this library.

class adafruit_fram.FRAM_SPI(spi_bus: SPI, spi_cs: DigitalInOut, write_protect: bool = False, wp_pin: DigitalInOut | None = None, baudrate: int = 100000, max_size: int = 8192)

SPI class for FRAM.

Parameters:

  • spi_bus (SPI) – The SPI bus the FRAM is connected to.

  • spi_cs (DigitalInOut) – The SPI CS pin.

  • write_protect (bool) – Turns on/off initial write protection. Default is False.

  • wp_pin – (Optional) Physical pin connected to the WP breakout pin. Must be a digitalio.DigitalInOut object.

  • baudrate (int) – SPI baudrate to use. Default is 1000000.

  • max_size (int) – Size of FRAM in Bytes. Default is 8192.

property write_protected: bool

The status of write protection. Default value on initialization is False.

When a WP pin is supplied during initialization, or using write_protect_pin, the status is tied to that pin and enables hardware-level protection.

When no WP pin is supplied, protection is only at the software level in this library.