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stm32: Add support for FDCAN on the STM32N6. #146

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f6477af
stm32: Add support for FDCAN on the STM32N6.
kwagyeman Jun 6, 2026
917afdc
stm32/boards/OPENMV_N6: Enable FDCAN on the OpenMV N6.
kwagyeman Jun 6, 2026
3e1f00e
tests/ports/stm32/pyb_can.py: Update test to run on STM32N6.
dpgeorge Jun 12, 2026
34b14a6
stm32/fdcan: Initialise all entries in FDCAN_InitTypeDef struct.
dpgeorge Jun 12, 2026
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2 changes: 1 addition & 1 deletion ports/stm32/Makefile
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Original file line number Diff line number Diff line change
Expand Up @@ -429,7 +429,7 @@ endif

ifeq ($(MCU_SERIES),$(filter $(MCU_SERIES),f0 f4 f7))
HAL_SRC_C += $(addprefix $(STM32LIB_HAL_BASE)/Src/stm32$(MCU_SERIES)xx_, hal_can.c)
else ifeq ($(MCU_SERIES),$(filter $(MCU_SERIES),g0 g4 h7))
else ifeq ($(MCU_SERIES),$(filter $(MCU_SERIES),g0 g4 h7 n6))
HAL_SRC_C += $(addprefix $(STM32LIB_HAL_BASE)/Src/stm32$(MCU_SERIES)xx_, hal_fdcan.c)
else ifeq ($(MCU_SERIES),$(filter $(MCU_SERIES),l4))
HAL_SRC_C += $(addprefix $(STM32LIB_HAL_BASE)/Src/Legacy/stm32$(MCU_SERIES)xx_, hal_can.c)
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9 changes: 9 additions & 0 deletions ports/stm32/boards/OPENMV_N6/mpconfigboard.h
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Original file line number Diff line number Diff line change
Expand Up @@ -78,6 +78,15 @@
#define MICROPY_HW_SPI4_MISO (pyb_pin_SPI4_MISO)
#define MICROPY_HW_SPI4_MOSI (pyb_pin_SPI4_MOSI)

// FDCAN bus
#define MICROPY_HW_CAN1_NAME "FDCAN1"
#define MICROPY_HW_CAN1_TX (pyb_pin_CAN1_TX)
#define MICROPY_HW_CAN1_RX (pyb_pin_CAN1_RX)
// Support is not yet added for FDCAN CAN3 (see fdcan.c for details)
// #define MICROPY_HW_CAN3_NAME "FDCAN3"
// #define MICROPY_HW_CAN3_TX (pyb_pin_CAN3_TX)
// #define MICROPY_HW_CAN3_RX (pyb_pin_CAN3_RX)

// USER is pulled high, and pressing the button makes the input go low.
#define MICROPY_HW_USRSW_PIN (pyb_pin_BUTTON)
#define MICROPY_HW_USRSW_PULL (GPIO_NOPULL)
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4 changes: 4 additions & 0 deletions ports/stm32/boards/OPENMV_N6/pins.csv
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Original file line number Diff line number Diff line change
Expand Up @@ -13,6 +13,8 @@ SPI2_CS,PA11
SPI2_SCK,PA12
UART4_RX,PA11
UART4_TX,PA12
CAN1_RX,PA11
CAN1_TX,PA12
P3,PA11
P2,PA12
,PA13
Expand Down Expand Up @@ -92,6 +94,8 @@ SPI4_CS,PE11
SPI4_SCK,PE12
P15,PE11
P16,PE12
CAN3_TX,PE11
CAN3_RX,PE12
I2C4_SCL,PE13
I2C4_SDA,PE14
,PE15
Expand Down
8 changes: 4 additions & 4 deletions ports/stm32/boards/stm32n657_af.csv
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Original file line number Diff line number Diff line change
Expand Up @@ -8,8 +8,8 @@ PortA,PA5 , , , ,
PortA,PA8 , , , , , , , , , , , , , , , , ,ADC12_INP5
PortA,PA9 , , , , , , , , , , , , , , , , ,ADC12_INP10
PortA,PA10, , , , , , , , , , , , , , , , ,ADC12_INP11/ADC12_INN10
PortA,PA11, , , , , ,SPI2_NSS ,CAN1_RXFD , ,UART4_RX , , , , , , , ,ADC12_INP12/ADC12_INN11
PortA,PA12, , , , , ,SPI2_SCK ,CAN1_TXFD , ,UART4_TX , , , , , , , ,ADC12_INP13/ADC12_INN12
PortA,PA11, , , , , ,SPI2_NSS ,CAN1_RX , ,UART4_RX , , , , , , , ,ADC12_INP12/ADC12_INN11
PortA,PA12, , , , , ,SPI2_SCK ,CAN1_TX , ,UART4_TX , , , , , , , ,ADC12_INP13/ADC12_INN12
PortB,PB4 , , , , , , , , , , , ,SDMMC2_D3 , , , , ,
PortB,PB6 , , , , , ,SPI4_MISO , ,TIM15_CH1 , , , , , , , , ,
PortB,PB7 , , , , , ,SPI4_MOSI , ,TIM15_CH2 , , , , , , , , ,
Expand All @@ -36,8 +36,8 @@ PortE,PE5 , , , ,
PortE,PE6 , , , , , , , ,USART1_RX , , , , , , , , ,
PortE,PE7 , , , , , , , , ,UART7_RX , , , , , , , ,
PortE,PE8 , , , , , , , , ,UART7_TX , , , , , , , ,
PortE,PE11, , , , , ,SPI4_NSS ,CAN3_TXFD , , , , , , , , , ,
PortE,PE12, , , , , ,SPI4_SCK ,CAN3_RXFD , , , , , , , , , ,
PortE,PE11, , , , , ,SPI4_NSS ,CAN3_TX , , , , , , , , , ,
PortE,PE12, , , , , ,SPI4_SCK ,CAN3_RX , , , , , , , , , ,
PortE,PE13, , , , ,I2C4_SCL , , , , , , , , , , , ,
PortE,PE14, , , , ,I2C4_SDA , , , , , , , , , , , ,
PortE,PE15, , , , , ,SPI5_SCK , , , , , , , , , , ,
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4 changes: 2 additions & 2 deletions ports/stm32/can.h
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Expand Up @@ -62,7 +62,7 @@
#if defined(STM32G4)
#define CAN_HW_MAX_STD_FILTER 28
#define CAN_HW_MAX_EXT_FILTER 8
#elif defined(STM32H7)
#elif defined(STM32H7) || defined(STM32N6)
// The RAM filtering section is configured for 64 x 1 word elements for 11-bit standard
// identifiers, and 31 x 2 words elements for 29-bit extended identifiers.
// The total number of words reserved for the filtering per FDCAN instance is 126 words.
Expand Down Expand Up @@ -123,7 +123,7 @@ typedef struct {
unsigned rx_fifo1_pending;
} can_counters_t;

#if defined(STM32H7)
#if defined(STM32H7) || defined(STM32N6)
#define CAN_TX_QUEUE_LEN 16
#else
// FDCAN STM32G4, bxCAN
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33 changes: 23 additions & 10 deletions ports/stm32/fdcan.c
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Expand Up @@ -53,17 +53,22 @@
#define FDCAN_IT_RX_FULL_MASK (FDCAN_IT_RX_FIFO0_FULL | FDCAN_IT_RX_FIFO1_FULL)
#define FDCAN_IT_RX_MESSAGE_LOST_MASK (FDCAN_IT_RX_FIFO0_MESSAGE_LOST | FDCAN_IT_RX_FIFO1_MESSAGE_LOST)

#if defined(STM32H7)
// adaptations for H7 to G4 naming convention in HAL
#if defined(STM32H7) || defined(STM32N6)
// adaptations for H7/N6 to G4 naming convention in HAL
#define FDCAN_IT_GROUP_RX_FIFO0 (FDCAN_ILS_RF0NL | FDCAN_ILS_RF0FL | FDCAN_ILS_RF0LL)
#if defined(STM32H7)
#define FDCAN_IT_GROUP_BIT_LINE_ERROR (FDCAN_ILS_EPE | FDCAN_ILS_ELOE)
#define FDCAN_IT_GROUP_PROTOCOL_ERROR (FDCAN_ILS_ARAE | FDCAN_ILS_PEDE | FDCAN_ILS_PEAE | FDCAN_ILS_WDIE | FDCAN_ILS_BOE | FDCAN_ILS_EWE)
#else
#define FDCAN_IT_GROUP_BIT_LINE_ERROR (FDCAN_ILS_EPL | FDCAN_ILS_ELOL)
#define FDCAN_IT_GROUP_PROTOCOL_ERROR (FDCAN_ILS_ARAL | FDCAN_ILS_PEDL | FDCAN_ILS_PEAL | FDCAN_ILS_WDIL | FDCAN_ILS_BOL | FDCAN_ILS_EWL)
#endif
#define FDCAN_IT_GROUP_RX_FIFO1 (FDCAN_ILS_RF1NL | FDCAN_ILS_RF1FL | FDCAN_ILS_RF1LL)

// The dedicated Message RAM should be 2560 words, but the way it's defined in stm32h7xx_hal_fdcan.c
// as (SRAMCAN_BASE + FDCAN_MESSAGE_RAM_SIZE - 0x4U) limits the usable number of words to 2559 words.
#define FDCAN_MESSAGE_RAM_SIZE (2560 - 1)
#endif // STM32H7
#endif // STM32H7 || STM32N6

#if defined(STM32G4)
// These HAL APIs are not implemented for STM32G4, so we implement them here...
Expand Down Expand Up @@ -132,6 +137,11 @@ bool can_init(CAN_HandleTypeDef *can, int can_id, can_tx_mode_t tx_mode, uint32_
init->NominalTimeSeg1 = bs1; // NominalTimeSeg1 = Propagation_segment + Phase_segment_1
init->NominalTimeSeg2 = bs2;

init->DataPrescaler = 1;
init->DataSyncJumpWidth = 1;
init->DataTimeSeg1 = 1;
init->DataTimeSeg2 = 1;

init->AutoRetransmission = ENABLE;
init->TransmitPause = DISABLE;
init->ProtocolException = ENABLE;
Expand All @@ -141,12 +151,8 @@ bool can_init(CAN_HandleTypeDef *can, int can_id, can_tx_mode_t tx_mode, uint32_

#if defined(STM32G4)
init->ClockDivider = FDCAN_CLOCK_DIV1;
init->DataPrescaler = 1;
init->DataSyncJumpWidth = 1;
init->DataTimeSeg1 = 1;
init->DataTimeSeg2 = 1;
init->TxFifoQueueMode = fifo_queue_mode;
#elif defined(STM32H7)
#elif defined(STM32H7) || defined(STM32N6)
// The dedicated FDCAN RAM is 2560 32-bit words and shared between the FDCAN instances.
// To support 2 FDCAN instances simultaneously, the Message RAM is divided in half by
// setting the second FDCAN memory offset to half the RAM size. With this configuration,
Expand Down Expand Up @@ -185,11 +191,12 @@ bool can_init(CAN_HandleTypeDef *can, int can_id, can_tx_mode_t tx_mode, uint32_
// 2 words header + 16 words data field (to support up to 64 bytes of data).
// The total number of words reserved for the Rx FIFOs per FDCAN instance is 864 words.
init->RxBuffersNbr = 0;
init->RxBufferSize = FDCAN_DATA_BYTES_64;
init->RxFifo0ElmtsNbr = 24;
init->RxFifo0ElmtSize = FDCAN_DATA_BYTES_64;
init->RxFifo1ElmtsNbr = 24;
init->RxFifo1ElmtSize = FDCAN_DATA_BYTES_64;
#endif // STM32H7
#endif // STM32H7 || STM32N6

const machine_pin_obj_t *pins[2];

Expand Down Expand Up @@ -316,7 +323,9 @@ void can_clearfilter(FDCAN_HandleTypeDef *can, uint32_t f, bool is_extid) {

uint32_t can_get_source_freq(void) {
// Find CAN kernel clock
#if defined(STM32H7)
#if defined(STM32N6)
return HAL_RCCEx_GetPeriphCLKFreq(RCC_PERIPHCLK_FDCAN);
#elif defined(STM32H7)
switch (__HAL_RCC_GET_FDCAN_SOURCE()) {
case RCC_FDCANCLKSOURCE_HSE:
return HSE_VALUE;
Expand Down Expand Up @@ -362,7 +371,11 @@ static void encode_datalength(CanTxMsgTypeDef *txmsg) {
size_t len_bytes = txmsg->DataLength;
for (mp_uint_t i = 0; i < MP_ARRAY_SIZE(DLCtoBytes); i++) {
if (len_bytes <= DLCtoBytes[i]) {
#if defined(STM32N6)
txmsg->DataLength = i;
#else
txmsg->DataLength = (i << 16);
#endif
return;
}
}
Expand Down
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