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stm32/pyb_can: Define the maximum bit timing parameters.

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Define the maximum parameters for CAN/FDCAN nominal bit timing, and for
FDCAN data bit timing, for bit timing calculations.
This commit is contained in:
iabdalkader 2022-01-30 19:16:17 +02:00 committed by Damien George
parent 95104c9f6e
commit a79706fb39
1 changed files with 24 additions and 7 deletions
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31
ports/stm32/pyb_can.c
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@ -59,6 +59,16 @@
#define CAN_DEFAULT_BS1 (8)
#define CAN_DEFAULT_BS2 (3)
#define CAN_MAXIMUM_NBRP (512)
#define CAN_MAXIMUM_NBS1 (256)
#define CAN_MAXIMUM_NBS2 (128)
// Minimum Nominal time segment for FDCAN is 2.
#define CAN_MINIMUM_TSEG (2)
#define CAN_MAXIMUM_DBRP (32)
#define CAN_MAXIMUM_DBS1 (32)
#define CAN_MAXIMUM_DBS2 (16)
#define CAN_MODE_NORMAL FDCAN_MODE_NORMAL
#define CAN_MODE_LOOPBACK FDCAN_MODE_EXTERNAL_LOOPBACK
#define CAN_MODE_SILENT FDCAN_MODE_BUS_MONITORING
@ -97,6 +107,11 @@ extern const uint8_t DLCtoBytes[16];
#define CAN_DEFAULT_BS1 (6)
#define CAN_DEFAULT_BS2 (8)
#define CAN_MAXIMUM_NBRP (1024)
#define CAN_MAXIMUM_NBS1 (16)
#define CAN_MAXIMUM_NBS2 (8)
#define CAN_MINIMUM_TSEG (1)
#define CAN_IT_FIFO0_FULL CAN_IT_FF0
#define CAN_IT_FIFO1_FULL CAN_IT_FF1
#define CAN_IT_FIFO0_OVRF CAN_IT_FOV0
@ -178,13 +193,13 @@ STATIC uint32_t pyb_can_get_source_freq() {
}
STATIC void pyb_can_get_bit_timing(mp_uint_t baudrate, mp_uint_t sample_point,
uint32_t max_brp, uint32_t max_bs1, uint32_t max_bs2, uint32_t min_tseg,
mp_int_t *bs1_out, mp_int_t *bs2_out, mp_int_t *prescaler_out) {
uint32_t can_kern_clk = pyb_can_get_source_freq();
// The following max values work on all MCUs for classical CAN.
for (int brp = 1; brp < 512; brp++) {
for (int bs1 = 1; bs1 < 16; bs1++) {
for (int bs2 = 1; bs2 < 8; bs2++) {
// Calculate CAN bit timing.
for (uint32_t brp = 1; brp < max_brp; brp++) {
for (uint32_t bs1 = min_tseg; bs1 < max_bs1; bs1++) {
for (uint32_t bs2 = min_tseg; bs2 < max_bs2; bs2++) {
if ((baudrate == (can_kern_clk / (brp * (1 + bs1 + bs2)))) &&
((sample_point * 10) == (((1 + bs1) * 1000) / (1 + bs1 + bs2)))) {
*bs1_out = bs1;
@ -229,9 +244,10 @@ STATIC mp_obj_t pyb_can_init_helper(pyb_can_obj_t *self, size_t n_args, const mp
// set the CAN configuration values
memset(&self->can, 0, sizeof(self->can));
// Calculate CAN bit timing from baudrate if provided
// Calculate CAN nominal bit timing from baudrate if provided
if (args[ARG_baudrate].u_int != 0) {
pyb_can_get_bit_timing(args[ARG_baudrate].u_int, args[ARG_sample_point].u_int,
CAN_MAXIMUM_NBRP, CAN_MAXIMUM_NBS1, CAN_MAXIMUM_NBS2, CAN_MINIMUM_TSEG,
&args[ARG_bs1].u_int, &args[ARG_bs2].u_int, &args[ARG_prescaler].u_int);
}
@ -240,9 +256,10 @@ STATIC mp_obj_t pyb_can_init_helper(pyb_can_obj_t *self, size_t n_args, const mp
if (args[ARG_brs_sample_point].u_int == 0) {
args[ARG_brs_sample_point].u_int = args[ARG_sample_point].u_int;
}
// Calculate BRS CAN bit timing from baudrate if provided
// Calculate CAN data bit timing from baudrate if provided
if (args[ARG_brs_baudrate].u_int != 0) {
pyb_can_get_bit_timing(args[ARG_brs_baudrate].u_int, args[ARG_brs_sample_point].u_int,
CAN_MAXIMUM_DBRP, CAN_MAXIMUM_DBS1, CAN_MAXIMUM_DBS2, 1,
&args[ARG_brs_bs1].u_int, &args[ARG_brs_bs2].u_int, &args[ARG_brs_prescaler].u_int);
}
// Set BRS bit timings.