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| author |  Nick Brassel <nick@tzarc.org> | 2019-06-02 09:04:09 +1000 |
|---|---|---|
| committer |  Drashna Jaelre <drashna@live.com> | 2019-06-01 16:04:09 -0700 |
| commit | 155be34a1d2b782a73318cc507315b33cc86cc49 (patch) | |
| tree | 842b3fa9e4881d18932a0e01666dec5a8144d3b2 /docs/i2c_driver.md | |
| parent | 4f788c2ae90583f64e0cec6545a3da75a5aff0f8 (diff) | |
| download | qmk_firmware-155be34a1d2b782a73318cc507315b33cc86cc49.tar.gz | |
Parameterise STM32 I2C pin modes and timing parameters. (#5671)
I2C timing parameters were seemingly set up for an STM32F303 target MCU, at a specific clock speed. This commit allows specifying the timing parameters via config.h, allowing other STM32 MCUs to be targeted, potentially at different clock frequencies.
Alternate function modes for the I2C pins are now also configurable, allowing for remapping to other pins.
Diffstat (limited to 'docs/i2c_driver.md')
| -rw-r--r-- | docs/i2c_driver.md | 29 |
1 files changed, 24 insertions, 5 deletions
diff --git a/docs/i2c_driver.md b/docs/i2c_driver.md index bb1a2d74f..4a47a92b1 100644 --- a/docs/i2c_driver.md +++ b/docs/i2c_driver.md @@ -65,11 +65,30 @@ By default the I2C1 hardware driver is assumed to be used. If another hardware d STM32 MCUs allows a variety of pins to be configured as I2C pins depending on the hardware driver used. By default B6 and B7 are set to I2C. You can use these defines to set your i2c pins: -| Variable | Description | Default | -|-------------|----------------------------------------------|---------| -| `I2C1_BANK` | The bank of pins (`GPIOA`, `GPIOB`, `GPIOC`) | `GPIOB` | -| `I2C1_SCL` | The pin number for the SCL pin (0-9) | `6` | -| `I2C1_SDA` | The pin number for the SDA pin (0-9) | `7` | +| Variable | Description | Default | +|--------------------------|----------------------------------------------------------------------------------------------|---------| +| `I2C1_SCL_BANK` | The bank of pins (`GPIOA`, `GPIOB`, `GPIOC`) to use for SCL | `GPIOB` | +| `I2C1_SDA_BANK` | The bank of pins (`GPIOA`, `GPIOB`, `GPIOC`) to use for SDA | `GPIOB` | +| `I2C1_SCL` | The pin number for the SCL pin (0-9) | `6` | +| `I2C1_SDA` | The pin number for the SDA pin (0-9) | `7` | +| `I2C1_BANK` (deprecated) | The bank of pins (`GPIOA`, `GPIOB`, `GPIOC`), superceded by `I2C1_SCL_BANK`, `I2C1_SDA_BANK` | `GPIOB` | + +STM32 MCUs allow for different timing parameters when configuring I2C. These can be modified using the following parameters, using https://www.st.com/en/embedded-software/stsw-stm32126.html as a reference: + +| Variable | Default | +|-----------------------|---------| +| `I2C1_TIMINGR_PRESC` | `15U` | +| `I2C1_TIMINGR_SCLDEL` | `4U` | +| `I2C1_TIMINGR_SDADEL` | `2U` | +| `I2C1_TIMINGR_SCLH` | `15U` | +| `I2C1_TIMINGR_SCLL` | `21U` | + +STM32 MCUs allow for different "alternate function" modes when configuring GPIO pins. These are required to switch the pins used to I2C mode. See the respective datasheet for the appropriate values for your MCU. + +| Variable | Default | +|---------------------|---------| +| `I2C1_SCL_PAL_MODE` | `4` | +| `I2C1_SDA_PAL_MODE` | `4` | You can also overload the `void i2c_init(void)` function, which has a weak attribute. If you do this the configuration variables above will not be used. Please consult the datasheet of your MCU for the available GPIO configurations. The following is an example initialization function: |