uint32_t _canConfig(uint32_t bitrate)
{
int prescaler = 0;
switch(bitrate)
{
case 500:
prescaler = 2; //500kb/s=2000ns
break;

case 250:
prescaler = 4; //250kb/s=4000ns
break;

case 125:
prescaler = 8; //125kb/s=8000ns
break;

case 100:
prescaler = 10; //100kb/s=10000ns
break;

case 50:
prescaler = 20; //50kb/s=20000ns
break;

case 20:
prescaler = 50; //20kb/s=50000ns
break;

case 10:
prescaler = 100; //10kb/s=100000ns
break;

default:
prescaler = 2; //500kb/s=2000ns
break;

}

//CANRX поставлено nopull по аналогии с халом
rcc_periph_clock_enable(CAN_RX_PERIPH);
gpio_mode_setup(CAN_RX_PORT, GPIO_MODE_INPUT, GPIO_PUPD_NONE, CAN_RX_PIN);
gpio_set(CAN_RX_PORT, CAN_RX_PIN);

//CANTX
rcc_periph_clock_enable(CAN_TX_PERIPH);
gpio_mode_setup(CAN_TX_PORT, GPIO_MODE_AF|GPIO_OSPEED_50MHZ, GPIO_OTYPE_PP, CAN_TX_PIN);

//CANmodul
rcc_periph_clock_enable(CAN_PERIPH);
nvic_enable_irq(NVIC_CAN1_RX0_IRQ);
nvic_set_priority(NVIC_CAN1_RX0_IRQ, 1);

can_reset(CAN_NUM);
if(can_init(CAN1,
false, //TTCM: Time triggered comm mode?
false, //ABOM: Automatic bus-off management?
false, //AWUM: Automatic wakeup mode?
false, //NART: No automatic retransmission?
false, //RFLM: Receive FIFO locked mode?
false, //TXFP: Transmit FIFO priority?
CAN_BTR_SJW_1TQ,
CAN_BTR_TS1_9TQ,
CAN_BTR_TS2_6TQ,
prescaler, //BRP+1: Baud rate prescaler
false, //LOOPBACK?
false) == 1) //SILENT?
{
return 1;
}

//CAN filter 0 init
can_filter_id_mask_32bit_init(
0, // Filter ID - принимать все
0, // CAN ID
0, // CAN ID mask
0, // FIFO assignment (here: FIFO0)
true); // Enable the filter

//Enable CAN RX interrupt
can_enable_irq(CAN1, CAN_IER_FMPIE0);

void can1_rx0_isr(void)
{
    can_fifo_release(CAN1, 0);
}

while (1)
    {
        time++;
        if(time>1000000)
        {
            can_transmit(CAN1, 0x00, 0, 0,8, datat);
            time=0;
        }

void HAL_CAN_MspInit(CAN_HandleTypeDef* hcan)
{

GPIO_InitTypeDef GPIO_InitStruct;
if(hcan->Instance==CAN1)
{
/* USER CODE BEGIN CAN1_MspInit 0 */

/* USER CODE END CAN1_MspInit 0 */
/* Peripheral clock enable */
__HAL_RCC_CAN1_CLK_ENABLE();

/**CAN1 GPIO Configuration
PB8 ------> CAN1_RX
PB9 ------> CAN1_TX
*/
GPIO_InitStruct.Pin = GPIO_PIN_8;
GPIO_InitStruct.Mode = GPIO_MODE_INPUT;
GPIO_InitStruct.Pull = GPIO_NOPULL;
HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);

GPIO_InitStruct.Pin = GPIO_PIN_9;
GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);

__HAL_AFIO_REMAP_CAN1_2();

/* Peripheral interrupt init */
HAL_NVIC_SetPriority(CAN1_RX0_IRQn, 0, 0);
HAL_NVIC_EnableIRQ(CAN1_RX0_IRQn);
HAL_NVIC_SetPriority(CAN1_SCE_IRQn, 0, 0);
HAL_NVIC_EnableIRQ(CAN1_SCE_IRQn);
/* USER CODE BEGIN CAN1_MspInit 1 */

/* USER CODE END CAN1_MspInit 1 */
}

}

CanTxMsgTypeDef tx;
tx.StdId = 0xFF;
tx.ExtId = 0xFF;
tx.RTR = CAN_RTR_DATA;
tx.IDE = CAN_ID_STD;
tx.DLC = 2;
tx.Data[0] = 'C';
tx.Dаta[1] = 'A';
hcan1.pTxMsg = &tx;

APB1_FREQ = 42 mHz
Prescaler (for TQ) = 24
42/24 = 1.75
1/1.75 * 1000 = 571.4 ns (Time Quantum)

Для скорости 250 kbit/s:
1/250*1000 = 4000 ns (time for One Bit)

571.4 * (1 + BS1 + BS2) = 4000
BS1+BS2 = 6 (пусть BS1 = 1, BS2 = 5)

Итого настройки CAN1 для скорости 250 Кбит/сек:
PRESC = 24
SJW = 1
BS1 = 1
BS2 = 5

APB1_FREQ = 36 mHz
Prescaler (for TQ) = 12
36/12 = 3
1/3 * 1000 = 333.3 ns (Time Quantum)

Для скорости 250 kbit/s:
1/250*1000 = 4000 ns (time for One Bit)

333.3 * (1 + BS1 + BS2) = 4000
BS1+BS2 = 11 (пусть BS1 = 6, BS2 = 5)

Итого настройки CAN1 для скорости 250 Кбит/сек:

PRESC = 12
SJW = 1
BS1 = 6
BS2 = 5

APB1_FREQ = 42 mHz
Prescaler (for TQ) = 24
42/24 = 1.75
1/1.75 * 1000 = 571.4 ns (Time Quantum)

Для скорости 250 kbit/s:
1/250*1000 = 4000 ns (time for One Bit)

571.4 * (1 + BS1 + BS2) = 4000
BS1+BS2 = 6 (пусть BS1 = 2, BS2 = 4)

Итого настройки CAN1 для скорости 250 Кбит/сек:
PRESC = 24
SJW = 1
BS1 = 2
BS2 = 4