diff options
| -rw-r--r-- | ports/nrf/common-hal/busio/SPI.c | 50 | ||||
| -rw-r--r-- | shared-bindings/busio/SPI.c | 6 |
2 files changed, 30 insertions, 26 deletions
diff --git a/ports/nrf/common-hal/busio/SPI.c b/ports/nrf/common-hal/busio/SPI.c index 8ff00d297..405d19c23 100644 --- a/ports/nrf/common-hal/busio/SPI.c +++ b/ports/nrf/common-hal/busio/SPI.c @@ -65,27 +65,27 @@ void spi_reset(void) { } } -// Convert frequency to clock-speed-dependent value. Choose the nearest value, lower or higher. +// Convert frequency to clock-speed-dependent value. Choose the next lower baudrate if in between +// available baudrates. static nrf_spim_frequency_t baudrate_to_spim_frequency(const uint32_t baudrate) { - // Round requested baudrate to nearest available baudrate. static const struct { const uint32_t boundary; nrf_spim_frequency_t spim_frequency; } baudrate_map[] = { #ifdef SPIM_FREQUENCY_FREQUENCY_M32 - { (16000000 + 32000000) / 2, NRF_SPIM_FREQ_32M }, + { 32000000, NRF_SPIM_FREQ_32M }, #endif #ifdef SPIM_FREQUENCY_FREQUENCY_M16 - { ( 8000000 + 16000000) / 2, NRF_SPIM_FREQ_16M }, + { 16000000, NRF_SPIM_FREQ_16M }, #endif - { ( 4000000 + 8000000) / 2, NRF_SPIM_FREQ_8M }, - { ( 2000000 + 4000000) / 2, NRF_SPIM_FREQ_4M }, - { ( 1000000 + 2000000) / 2, NRF_SPIM_FREQ_2M }, - { ( 500000 + 1000000) / 2, NRF_SPIM_FREQ_1M }, - { ( 250000 + 500000) / 2, NRF_SPIM_FREQ_500K }, - { ( 125000 + 250000) / 2, NRF_SPIM_FREQ_250K }, - { 0, NRF_SPIM_FREQ_125K }, + { 8000000, NRF_SPIM_FREQ_8M }, + { 4000000, NRF_SPIM_FREQ_4M }, + { 2000000, NRF_SPIM_FREQ_2M }, + { 1000000, NRF_SPIM_FREQ_1M }, + { 500000, NRF_SPIM_FREQ_500K }, + { 250000, NRF_SPIM_FREQ_250K }, + { 0, NRF_SPIM_FREQ_125K }, }; size_t i = 0; @@ -97,7 +97,7 @@ static nrf_spim_frequency_t baudrate_to_spim_frequency(const uint32_t baudrate) } i++; } while (boundary != 0); - // Will get here only if baudrate == 0. + // Should not get here. return 0; } @@ -168,22 +168,26 @@ void common_hal_busio_spi_deinit(busio_spi_obj_t *self) { } bool common_hal_busio_spi_configure(busio_spi_obj_t *self, uint32_t baudrate, uint8_t polarity, uint8_t phase, uint8_t bits) { - // nrf52 does not support 16 bit - if (bits != 8) + // nrf52 does not support 16 bit + if (bits != 8) { return false; + } - nrf_spim_frequency_set(self->spim_peripheral->spim.p_reg, baudrate_to_spim_frequency(baudrate)); + // Set desired frequency, rounding down, and don't go above available frequency for this SPIM. + nrf_spim_frequency_set(self->spim_peripheral->spim.p_reg, + baudrate_to_spim_frequency(MIN(baudrate, + self->spim_peripheral->max_frequency_MHz * 1000000))); - nrf_spim_mode_t mode = NRF_SPIM_MODE_0; - if (polarity) { - mode = (phase) ? NRF_SPIM_MODE_3 : NRF_SPIM_MODE_2; - } else { - mode = (phase) ? NRF_SPIM_MODE_1 : NRF_SPIM_MODE_0; - } + nrf_spim_mode_t mode = NRF_SPIM_MODE_0; + if (polarity) { + mode = (phase) ? NRF_SPIM_MODE_3 : NRF_SPIM_MODE_2; + } else { + mode = (phase) ? NRF_SPIM_MODE_1 : NRF_SPIM_MODE_0; + } - nrf_spim_configure(self->spim_peripheral->spim.p_reg, mode, NRF_SPIM_BIT_ORDER_MSB_FIRST); + nrf_spim_configure(self->spim_peripheral->spim.p_reg, mode, NRF_SPIM_BIT_ORDER_MSB_FIRST); - return true; + return true; } bool common_hal_busio_spi_try_lock(busio_spi_obj_t *self) { diff --git a/shared-bindings/busio/SPI.c b/shared-bindings/busio/SPI.c index be5f431ec..d30bbbe06 100644 --- a/shared-bindings/busio/SPI.c +++ b/shared-bindings/busio/SPI.c @@ -136,7 +136,7 @@ static void check_lock(busio_spi_obj_t *self) { //| .. method:: SPI.configure(\*, baudrate=100000, polarity=0, phase=0, bits=8) //| -//| Configures the SPI bus. Only valid when locked. +//| Configures the SPI bus. The SPI object must be locked. //| //| :param int baudrate: the desired clock rate in Hertz. The actual clock rate may be higher or lower //| due to the granularity of available clock settings. @@ -154,8 +154,8 @@ static void check_lock(busio_spi_obj_t *self) { //| and 8MHz. On the nRF52840, 16MHz and 32MHz are also available, but only on the first //| `busio.SPI` object you create. Two more ``busio.SPI`` objects can be created, but they are restricted //| to 8MHz maximum. This is a hardware restriction: there is only one high-speed SPI peripheral. -//| If you pick a a baudrate other than one of these, the nearest available -//| baudrate will be chosen. +//| If you pick a a baudrate other than one of these, the nearest lower +//| baudrate will be chosen, with a minimum of 125kHz. STATIC mp_obj_t busio_spi_configure(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) { enum { ARG_baudrate, ARG_polarity, ARG_phase, ARG_bits }; static const mp_arg_t allowed_args[] = { |