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[STM32L4xx] Change SPI clock selection 

Update of STM32L4 family CPI clock selection algo.
Maximum SPI clock is obtained from APB domain clock (based on HAL API).
Then algo sets maximum frequency available below requested frequency
pull/2013/head
Erwan GOURIOU 2016-06-22 16:04:15 +02:00
parent 67e6f729c7
commit bc08631931
1 changed files with 37 additions and 37 deletions
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74
hal/targets/hal/TARGET_STM/TARGET_STM32L4/spi_api.c
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@ -187,47 +187,47 @@ void spi_format(spi_t *obj, int bits, int mode, int slave)
init_spi(obj);
}
static const uint16_t baudrate_prescaler_table[] = {SPI_BAUDRATEPRESCALER_2,
SPI_BAUDRATEPRESCALER_4,
SPI_BAUDRATEPRESCALER_8,
SPI_BAUDRATEPRESCALER_16,
SPI_BAUDRATEPRESCALER_32,
SPI_BAUDRATEPRESCALER_64,
SPI_BAUDRATEPRESCALER_128,
SPI_BAUDRATEPRESCALER_256};
void spi_frequency(spi_t *obj, int hz)
{
// Values depend of PCLK1 and PCLK2: 80 MHz if MSI or HSI is used, 48 MHz if HSE is used
if (SystemCoreClock == 80000000) { // MSI or HSI
if (hz < 600000) {
obj->br_presc = SPI_BAUDRATEPRESCALER_256; // 313 kHz
} else if ((hz >= 600000) && (hz < 1000000)) {
obj->br_presc = SPI_BAUDRATEPRESCALER_128; // 625 kHz
} else if ((hz >= 1000000) && (hz < 2000000)) {
obj->br_presc = SPI_BAUDRATEPRESCALER_64; // 1.25 MHz (default)
} else if ((hz >= 2000000) && (hz < 5000000)) {
obj->br_presc = SPI_BAUDRATEPRESCALER_32; // 2.5 MHz
} else if ((hz >= 5000000) && (hz < 10000000)) {
obj->br_presc = SPI_BAUDRATEPRESCALER_16; // 5 MHz
} else if ((hz >= 10000000) && (hz < 20000000)) {
obj->br_presc = SPI_BAUDRATEPRESCALER_8; // 10 MHz
} else if ((hz >= 20000000) && (hz < 40000000)) {
obj->br_presc = SPI_BAUDRATEPRESCALER_4; // 20 MHz
} else { // >= 40000000
obj->br_presc = SPI_BAUDRATEPRESCALER_2; // 40 MHz
}
} else { // 48 MHz - HSE
if (hz < 350000) {
obj->br_presc = SPI_BAUDRATEPRESCALER_256; // 188 kHz
} else if ((hz >= 350000) && (hz < 750000)) {
obj->br_presc = SPI_BAUDRATEPRESCALER_128; // 375 kHz
} else if ((hz >= 750000) && (hz < 1000000)) {
obj->br_presc = SPI_BAUDRATEPRESCALER_64; // 750 kHz
} else if ((hz >= 1000000) && (hz < 3000000)) {
obj->br_presc = SPI_BAUDRATEPRESCALER_32; // 1.5 MHz (default)
} else if ((hz >= 3000000) && (hz < 6000000)) {
obj->br_presc = SPI_BAUDRATEPRESCALER_16; // 3 MHz
} else if ((hz >= 6000000) && (hz < 12000000)) {
obj->br_presc = SPI_BAUDRATEPRESCALER_8; // 6 MHz
} else if ((hz >= 12000000) && (hz < 24000000)) {
obj->br_presc = SPI_BAUDRATEPRESCALER_4; // 12 MHz
} else { // >= 24000000
obj->br_presc = SPI_BAUDRATEPRESCALER_2; // 24 MHz
}
int spi_hz = 0;
uint8_t prescaler_rank = 0;
/* Get source clock depending on SPI instance */
switch ((int)obj->spi) {
case SPI_1:
/* SPI_1. Source CLK is PCKL2 */
spi_hz = HAL_RCC_GetPCLK2Freq();
break;
case SPI_2:
case SPI_3:
/* SPI_2, SPI_3. Source CLK is PCKL1 */
spi_hz = HAL_RCC_GetPCLK1Freq();
break;
default:
error("SPI instance not set");
}
/* 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]))){
spi_hz = spi_hz / 2;
prescaler_rank++;
}
if (prescaler_rank <= sizeof(baudrate_prescaler_table)/sizeof(baudrate_prescaler_table[0])) {
obj->br_presc = baudrate_prescaler_table[prescaler_rank-1];
} else {
error("Couldn't setup requested SPI frequency");
}
init_spi(obj);
}