Adafruit seesaw

by Dean Miller

published November 01, 2017, last updated June 27, 2023

posted in Sensors CircuitPython Breakout Boards

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Product guide

EEPROM

The EEPROM module provides persistent storage of data across reboots.

On the SAMD09, there are 64 bytes of emulated EEPROM available for use. Byte 63 (0x3F) can be written to change the devices default I2C address.

On the ATtiny817, there are 128 bytes of actual EEPROM available for use. Byte 127 (0x7F) can be written to change the device's default I2C address.

The module base register address for the EEPROM module is 0x0D

The SAMD09 does not have true EEPROM, but flash memory on the seesaw that performs the same function. Performing a chip erase will erase all data stored in the emulated EEPROM. Also, be aware that the emulated EEPROM has a limited write/erase cycle lifespan. Care should be taken to not write/erase too many times or you will get inconsistant results and possibly damage the FLASH! The FLASH is rated for 100,000 cycles

Function Registers

SAMD09

Register Address	Function Name	Register Size	Notes
0x00 - 0x3E	General Purpose EEPROM	8 bits each	Read/Write
0x3F	I2C Address	8 bits	Read/Write

ATtiny817

Register Address	Function Name	Register Size	Notes
0x00 - 0x7E	General purpose EEPROM	8 bits each	Read/write
0x7F	I2C Address	8 bits	Read/write