diff options
| author | Scott Shawcroft <scott.shawcroft@gmail.com> | 2018-03-26 16:32:16 -0700 |
|---|---|---|
| committer | Scott Shawcroft <scott.shawcroft@gmail.com> | 2018-03-26 16:32:16 -0700 |
| commit | cebcec5e63d594dda93917ffbecfde6d6fe5c5ca (patch) | |
| tree | 6c4ba456b72267476751ac43b7cb9af6b603a50b | |
| parent | 25ba8ee489f5d17053ec625590d608a55020793a (diff) | |
Check for floating pins by pulling them low briefly before testing their values.
| -rw-r--r-- | ports/atmel-samd/common-hal/busio/I2C.c | 18 |
1 files changed, 17 insertions, 1 deletions
diff --git a/ports/atmel-samd/common-hal/busio/I2C.c b/ports/atmel-samd/common-hal/busio/I2C.c index c5cd5d8b5..77676b535 100644 --- a/ports/atmel-samd/common-hal/busio/I2C.c +++ b/ports/atmel-samd/common-hal/busio/I2C.c @@ -34,6 +34,7 @@ #include "peripherals.h" #include "pins.h" +#include "shared-bindings/microcontroller/__init__.h" // Number of times to try to send packet if failed. @@ -77,10 +78,21 @@ void common_hal_busio_i2c_construct(busio_i2c_obj_t *self, gpio_set_pin_function(scl->pin, GPIO_PIN_FUNCTION_OFF); gpio_set_pin_direction(sda->pin, GPIO_DIRECTION_IN); gpio_set_pin_direction(scl->pin, GPIO_DIRECTION_IN); + + gpio_set_pin_pull_mode(sda->pin, GPIO_PULL_DOWN); + gpio_set_pin_pull_mode(scl->pin, GPIO_PULL_DOWN); + + common_hal_mcu_delay_us(10); + gpio_set_pin_pull_mode(sda->pin, GPIO_PULL_OFF); gpio_set_pin_pull_mode(scl->pin, GPIO_PULL_OFF); + // We must pull up within 3us to achieve 400khz. + common_hal_mcu_delay_us(3); + if (!gpio_get_pin_level(sda->pin) || !gpio_get_pin_level(scl->pin)) { + reset_pin(sda->pin); + reset_pin(scl->pin); mp_raise_RuntimeError("SDA or SCL needs a pull up"); } gpio_set_pin_function(sda->pin, sda_pinmux); @@ -90,13 +102,17 @@ void common_hal_busio_i2c_construct(busio_i2c_obj_t *self, samd_peripherals_sercom_clock_init(sercom, sercom_index); if (i2c_m_sync_init(&self->i2c_desc, sercom) != ERR_NONE) { - mp_raise_OSError(MP_EIO); + reset_pin(sda->pin); + reset_pin(scl->pin); + mp_raise_OSError(MP_EIO); } // clkrate is always 0. baud_rate is in kHz. // Frequency must be set before the I2C device is enabled. if (i2c_m_sync_set_baudrate(&self->i2c_desc, 0, frequency / 1000) != ERR_NONE) { + reset_pin(sda->pin); + reset_pin(scl->pin); mp_raise_ValueError("Unsupported baudrate"); } |