- # I2C Master Driver :id=i2c-master-driver
-
- The I2C Master drivers used in QMK have a set of common functions to allow portability between MCUs.
-
- ## Usage :id=usage
-
- In most cases, the I2C Master driver code is automatically included if you are using a feature or driver which requires it, such as [OLED](feature_oled_driver.md).
-
- However, if you need to use the driver standalone, add the following to your `rules.mk`:
-
- ```make
- I2C_DRIVER_REQUIRED = yes
- ```
-
- You can then call the I2C API by including `i2c_master.h` in your code.
-
- ## I2C Addressing :id=note-on-i2c-addresses
-
- All of the addresses expected by this driver should be pushed to the upper 7 bits of the address byte. Setting
- the lower bit (indicating read/write) will be done by the respective functions. Almost all I2C addresses listed
- on datasheets and the internet will be represented as 7 bits occupying the lower 7 bits and will need to be
- shifted to the left (more significant) by one bit. This is easy to do via the bitwise shift operator `<< 1`.
-
- You can either do this on each call to the functions below, or once in your definition of the address. For example, if your device has an address of `0x18`:
-
- ```c
- #define MY_I2C_ADDRESS (0x18 << 1)
- ```
-
- See https://www.robot-electronics.co.uk/i2c-tutorial for more information about I2C addressing and other technical details.
-
- ## AVR Configuration :id=avr-configuration
-
- The following defines can be used to configure the I2C master driver:
-
- |`config.h` Override|Description |Default |
- |-------------------|---------------------|--------|
- |`F_SCL` |Clock frequency in Hz|`400000`|
-
- No further setup is required - just connect the `SDA` and `SCL` pins of your I2C devices to the matching pins on the MCU:
-
- |MCU |`SCL`|`SDA`|
- |------------------|-----|-----|
- |ATmega16/32U4 |`D0` |`D1` |
- |AT90USB64/128 |`D0` |`D1` |
- |ATmega32A |`C0` |`C1` |
- |ATmega328/P |`C5` |`C4` |
-
- ?> The ATmega16/32U2 does not possess I2C functionality, and so cannot use this driver.
-
- ## ChibiOS/ARM Configuration :id=arm-configuration
-
- You'll need to determine which pins can be used for I2C -- a an example, STM32 parts generally have multiple I2C peripherals, labeled I2C1, I2C2, I2C3 etc.
-
- To enable I2C, modify your board's `halconf.h` to enable I2C:
-
- ```c
- #define HAL_USE_I2C TRUE
- ```
-
- Then, modify your board's `mcuconf.h` to enable the peripheral you've chosen, for example:
-
- ```c
- #undef STM32_I2C_USE_I2C2
- #define STM32_I2C_USE_I2C2 TRUE
- ```
-
- |`mcuconf.h` Setting |Description |Default|
- |----------------------------|----------------------------------------------------------------------------------|-------|
- |`STM32_I2C_BUSY_TIMEOUT` |Time in milliseconds until the I2C command is aborted if no response is received |`50` |
- |`STM32_I2C_XXX_IRQ_PRIORITY`|Interrupt priority for hardware driver XXX (THIS IS AN EXPERT SETTING) |`10` |
- |`STM32_I2C_USE_DMA` |Enable/Disable the ability of the MCU to offload the data transfer to the DMA unit|`TRUE` |
- |`STM32_I2C_XXX_DMA_PRIORITY`|Priority of DMA unit for hardware driver XXX (THIS IS AN EXPERT SETTING) |`1` |
-
- Configuration-wise, you'll need to set up the peripheral as per your MCU's datasheet -- the defaults match the pins for a Proton-C, i.e. STM32F303.
-
- |`config.h` Overrride |Description |Default|
- |------------------------|--------------------------------------------------------------|-------|
- |`I2C_DRIVER` |I2C peripheral to use - I2C1 -> `I2CD1`, I2C2 -> `I2CD2` etc. |`I2CD1`|
- |`I2C1_SCL_PIN` |The pin definition for SCL |`B6` |
- |`I2C1_SCL_PAL_MODE` |The alternate function mode for SCL |`4` |
- |`I2C1_SDA_PIN` |The pin definition for SDA |`B7` |
- |`I2C1_SDA_PAL_MODE` |The alternate function mode for SDA |`4` |
-
- The following configuration values depend on the specific MCU in use.
-
- ### I2Cv1 :id=arm-configuration-i2cv1
-
- * STM32F1xx
- * STM32F2xx
- * STM32F4xx
- * STM32L0xx
- * STM32L1xx
-
- See [this page](https://www.playembedded.org/blog/stm32-i2c-chibios/#7_I2Cv1_configuration_structure) for the I2Cv1 configuration structure.
-
- |`config.h` Override|Default |
- |-------------------|----------------|
- |`I2C1_OPMODE` |`OPMODE_I2C` |
- |`I2C1_CLOCK_SPEED` |`100000` |
- |`I2C1_DUTY_CYCLE` |`STD_DUTY_CYCLE`|
-
- ### I2Cv2 :id=arm-configuration-i2cv2
-
- * STM32F0xx
- * STM32F3xx
- * STM32F7xx
- * STM32L4xx
-
- See [this page](https://www.playembedded.org/blog/stm32-i2c-chibios/#8_I2Cv2_I2Cv3_configuration_structure) for the I2Cv2 configuration structure.
-
- |`config.h` Override |Default|
- |---------------------|-------|
- |`I2C1_TIMINGR_PRESC` |`0U` |
- |`I2C1_TIMINGR_SCLDEL`|`7U` |
- |`I2C1_TIMINGR_SDADEL`|`0U` |
- |`I2C1_TIMINGR_SCLH` |`38U` |
- |`I2C1_TIMINGR_SCLL` |`129U` |
-
- ## API :id=api
-
- ### `void i2c_init(void)` :id=api-i2c-init
-
- Initialize the I2C driver. This function must be called only once, before any of the below functions can be called.
-
- This function is weakly defined, meaning it can be overridden if necessary for your particular use case:
-
- ```c
- void i2c_init(void) {
- gpio_set_pin_input(B6); // Try releasing special pins for a short time
- gpio_set_pin_input(B7);
- wait_ms(10); // Wait for the release to happen
-
- palSetPadMode(GPIOB, 6, PAL_MODE_ALTERNATE(4) | PAL_STM32_OTYPE_OPENDRAIN | PAL_STM32_PUPDR_PULLUP); // Set B6 to I2C function
- palSetPadMode(GPIOB, 7, PAL_MODE_ALTERNATE(4) | PAL_STM32_OTYPE_OPENDRAIN | PAL_STM32_PUPDR_PULLUP); // Set B7 to I2C function
- }
- ```
-
- ---
-
- ### `i2c_status_t i2c_transmit(uint8_t address, uint8_t *data, uint16_t length, uint16_t timeout)` :id=api-i2c-transmit
-
- Send multiple bytes to the selected I2C device.
-
- #### Arguments :id=api-i2c-transmit-arguments
-
- - `uint8_t address`
- The 7-bit I2C address of the device.
- - `uint8_t *data`
- A pointer to the data to transmit.
- - `uint16_t length`
- The number of bytes to write. Take care not to overrun the length of `data`.
- - `uint16_t timeout`
- The time in milliseconds to wait for a response from the target device.
-
- #### Return Value :id=api-i2c-transmit-return
-
- `I2C_STATUS_TIMEOUT` if the timeout period elapses, `I2C_STATUS_ERROR` if some other error occurs, otherwise `I2C_STATUS_SUCCESS`.
-
- ---
-
- ### `i2c_status_t i2c_receive(uint8_t address, uint8_t* data, uint16_t length, uint16_t timeout)` :id=api-i2c-receive
-
- Receive multiple bytes from the selected I2C device.
-
- #### Arguments :id=api-i2c-receive-arguments
-
- - `uint8_t address`
- The 7-bit I2C address of the device.
- - `uint8_t *data`
- A pointer to the buffer to read into.
- - `uint16_t length`
- The number of bytes to read. Take care not to overrun the length of `data`.
- - `uint16_t timeout`
- The time in milliseconds to wait for a response from the target device.
-
- #### Return Value :id=api-i2c-receive-return
-
- `I2C_STATUS_TIMEOUT` if the timeout period elapses, `I2C_STATUS_ERROR` if some other error occurs, otherwise `I2C_STATUS_SUCCESS`.
-
- ---
-
- ### `i2c_status_t i2c_write_register(uint8_t devaddr, uint8_t regaddr, uint8_t* data, uint16_t length, uint16_t timeout)` :id=api-i2c-write-register
-
- Writes to a register with an 8-bit address on the I2C device.
-
- #### Arguments :id=api-i2c-write-register-arguments
-
- - `uint8_t devaddr`
- The 7-bit I2C address of the device.
- - `uint8_t regaddr`
- The register address to write to.
- - `uint8_t *data`
- A pointer to the data to transmit.
- - `uint16_t length`
- The number of bytes to write. Take care not to overrun the length of `data`.
- - `uint16_t timeout`
- The time in milliseconds to wait for a response from the target device.
-
- #### Return Value :id=api-i2c-write-register-return
-
- `I2C_STATUS_TIMEOUT` if the timeout period elapses, `I2C_STATUS_ERROR` if some other error occurs, otherwise `I2C_STATUS_SUCCESS`.
-
- ---
-
- ### `i2c_status_t i2c_write_register16(uint8_t devaddr, uint16_t regaddr, uint8_t* data, uint16_t length, uint16_t timeout)` :id=api-i2c-write-register16
-
- Writes to a register with a 16-bit address (big endian) on the I2C device.
-
- #### Arguments :id=api-i2c-write-register16-arguments
-
- - `uint8_t devaddr`
- The 7-bit I2C address of the device.
- - `uint16_t regaddr`
- The register address to write to.
- - `uint8_t *data`
- A pointer to the data to transmit.
- - `uint16_t length`
- The number of bytes to write. Take care not to overrun the length of `data`.
- - `uint16_t timeout`
- The time in milliseconds to wait for a response from the target device.
-
- #### Return Value :id=api-i2c-write-register16-return
-
- `I2C_STATUS_TIMEOUT` if the timeout period elapses, `I2C_STATUS_ERROR` if some other error occurs, otherwise `I2C_STATUS_SUCCESS`.
-
- ---
-
- ### `i2c_status_t i2c_read_register(uint8_t devaddr, uint8_t regaddr, uint8_t* data, uint16_t length, uint16_t timeout)` :id=api-i2c-read-register
-
- Reads from a register with an 8-bit address on the I2C device.
-
- #### Arguments :id=api-i2c-read-register-arguments
-
- - `uint8_t devaddr`
- The 7-bit I2C address of the device.
- - `uint8_t regaddr`
- The register address to read from.
- - `uint16_t length`
- The number of bytes to read. Take care not to overrun the length of `data`.
- - `uint16_t timeout`
- The time in milliseconds to wait for a response from the target device.
-
- #### Return Value :id=api-i2c-read-register-return
-
- `I2C_STATUS_TIMEOUT` if the timeout period elapses, `I2C_STATUS_ERROR` if some other error occurs, otherwise `I2C_STATUS_SUCCESS`.
-
- ---
-
- ### `i2c_status_t i2c_read_register16(uint8_t devaddr, uint16_t regaddr, uint8_t* data, uint16_t length, uint16_t timeout)` :id=api-i2c-read-register16
-
- Reads from a register with a 16-bit address (big endian) on the I2C device.
-
- #### Arguments :id=api-i2c-read-register16-arguments
-
- - `uint8_t devaddr`
- The 7-bit I2C address of the device.
- - `uint16_t regaddr`
- The register address to read from.
- - `uint16_t length`
- The number of bytes to read. Take care not to overrun the length of `data`.
- - `uint16_t timeout`
- The time in milliseconds to wait for a response from the target device.
-
- #### Return Value :id=api-i2c-read-register16-return
-
- `I2C_STATUS_TIMEOUT` if the timeout period elapses, `I2C_STATUS_ERROR` if some other error occurs, otherwise `I2C_STATUS_SUCCESS`.
-
- ---
-
- ### `i2c_status_t i2c_ping_address(uint8_t address, uint16_t timeout)` :id=api-i2c-ping-address
-
- Pings the I2C bus for a specific address.
-
- On ChibiOS a "best effort" attempt is made by reading a single byte from register 0 at the requested address. This should generally work except for I2C devices that do not not respond to a register 0 read request, which will result in a false negative result (unsucessful response to ping attempt).
-
- This function is weakly defined, meaning it can be overridden if necessary for your particular use case:
-
- #### Arguments
-
- - `uint8_t address`
- The 7-bit I2C address of the device (ie. without the read/write bit - this will be set automatically).
- - `uint16_t timeout`
- The time in milliseconds to wait for a response from the target device.
-
- #### Return Value
-
- `I2C_STATUS_TIMEOUT` if the timeout period elapses, `I2C_STATUS_ERROR` if some other error occurs, otherwise `I2C_STATUS_SUCCESS`.
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