Skip to content

STM32: spi_frequency table index fix #3759

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 1 commit into from
Feb 21, 2017
Merged

STM32: spi_frequency table index fix #3759

Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
19 changes: 12 additions & 7 deletions targets/TARGET_STM/stm_spi_api.c
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -291,23 +291,28 @@ void spi_frequency(spi_t *obj, int hz) {
struct spi_s *spiobj = SPI_S(obj);
int spi_hz = 0;
uint8_t prescaler_rank = 0;
uint8_t last_index = (sizeof(baudrate_prescaler_table)/sizeof(baudrate_prescaler_table[0])) - 1;
SPI_HandleTypeDef *handle = &(spiobj->handle);

/* Get the clock of the peripheral */
spi_hz = spi_get_clock_freq(obj);
/* Calculate the spi clock for prescaler_rank 0: SPI_BAUDRATEPRESCALER_2 */
spi_hz = spi_get_clock_freq(obj) / 2;

/* Define pre-scaler in order to get highest available frequency below requested frequency */
while ((spi_hz > hz) && (prescaler_rank < sizeof(baudrate_prescaler_table)/sizeof(baudrate_prescaler_table[0]))){
while ((spi_hz > hz) && (prescaler_rank < last_index)) {
spi_hz = spi_hz / 2;
prescaler_rank++;
}

if (prescaler_rank <= sizeof(baudrate_prescaler_table)/sizeof(baudrate_prescaler_table[0])) {
handle->Init.BaudRatePrescaler = baudrate_prescaler_table[prescaler_rank-1];
} else {
error("Couldn't setup requested SPI frequency");
/* Use the best fit pre-scaler */
handle->Init.BaudRatePrescaler = baudrate_prescaler_table[prescaler_rank];

/* In case maximum pre-scaler still gives too high freq, raise an error */
if (spi_hz > hz) {
error("Couldn't set suitable spi freq: request:%d, lowest:%d\r\n", hz, spi_hz);
}

DEBUG_PRINTF("spi_frequency, request:%d, select:%d\r\n", hz, spi_hz);

init_spi(obj);
}

Expand Down