mirror of
https://github.com/qmk/qmk_firmware.git
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51 lines
3.9 KiB
Markdown
51 lines
3.9 KiB
Markdown
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# EEPROM Driver Configuration
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The EEPROM driver can be swapped out depending on the needs of the keyboard, or whether extra hardware is present.
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Driver | Description
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--------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
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`EEPROM_DRIVER = vendor` | Uses the on-chip driver provided by the chip manufacturer. For AVR, this is provided by avr-libc. This is supported on ARM for a subset of chips -- STM32F3xx, STM32F1xx, and STM32F072xB will be emulated by writing to flash. Other chips will generally act as "transient" below.
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`EEPROM_DRIVER = i2c` | Supports writing to I2C-based 24xx EEPROM chips. See the driver section below.
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`EEPROM_DRIVER = transient` | Fake EEPROM driver -- supports reading/writing to RAM, and will be discarded when power is lost.
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## Vendor Driver Configuration
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No configurable options are available.
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## I2C Driver Configuration
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Currently QMK supports 24xx-series chips over I2C. As such, requires a working i2c_master driver configuration. You can override the driver configuration via your config.h:
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`config.h` override | Description | Default Value
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------------------------------------------- | ----------------------------------------------------------------------------------- | ------------------------------------
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`#define EXTERNAL_EEPROM_I2C_BASE_ADDRESS` | Base I2C address for the EEPROM -- shifted left by 1 as per i2c_master requirements | 0b10100000
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`#define EXTERNAL_EEPROM_I2C_ADDRESS(addr)` | Calculated I2C address for the EEPROM | `(EXTERNAL_EEPROM_I2C_BASE_ADDRESS)`
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`#define EXTERNAL_EEPROM_BYTE_COUNT` | Total size of the EEPROM in bytes | 8192
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`#define EXTERNAL_EEPROM_PAGE_SIZE` | Page size of the EEPROM in bytes, as specified in the datasheet | 32
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`#define EXTERNAL_EEPROM_ADDRESS_SIZE` | The number of bytes to transmit for the memory location within the EEPROM | 2
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`#define EXTERNAL_EEPROM_WRITE_TIME` | Write cycle time of the EEPROM, as specified in the datasheet | 5
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Default values and extended descriptions can be found in `drivers/eeprom/eeprom_i2c.h`.
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Alternatively, there are pre-defined hardware configurations for available chips/modules:
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Module | Equivalent `#define` | Source
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-----------------|---------------------------------|------------------------------------------
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CAT24C512 EEPROM | `#define EEPROM_I2C_CAT24C512` | <https://www.sparkfun.com/products/14764>
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RM24C512C EEPROM | `#define EEPROM_I2C_RM24C512C` | <https://www.sparkfun.com/products/14764>
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24LC128 EEPROM | `#define EEPROM_I2C_24LC128` | <https://www.microchip.com/wwwproducts/en/24LC128>
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24LC256 EEPROM | `#define EEPROM_I2C_24LC256` | <https://www.sparkfun.com/products/525>
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MB85RC256V FRAM | `#define EEPROM_I2C_MB85RC256V` | <https://www.adafruit.com/product/1895>
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?> If you find that the EEPROM is not cooperating, ensure you've correctly shifted up your EEPROM address by 1. For example, the datasheet might state the address as `0b01010000` -- the correct value of `EXTERNAL_EEPROM_I2C_BASE_ADDRESS` needs to be `0b10100000`.
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## Transient Driver configuration
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The only configurable item for the transient EEPROM driver is its size:
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`config.h` override | Description | Default Value
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------------------------------- | ----------------------------------------- | -------------
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`#define TRANSIENT_EEPROM_SIZE` | Total size of the EEPROM storage in bytes | 64
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Default values and extended descriptions can be found in `drivers/eeprom/eeprom_transient.h`.
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