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stm32/pyb_can: Enable CAN FD frame support and BRS.
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- Enable CAN FD frame support and BRS.
- Optimize the message RAM usage per FDCAN instance.
- Document the usage and different sections of the Message RAM.
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@iabdalkader @dpgeorge
iabdalkader authored and dpgeorge committed Apr 2, 2022
1 parent 8baf05a commit ff287d0
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98 changes: 60 additions & 38 deletions ports/stm32/fdcan.c
View file
Expand Up @@ -56,14 +56,19 @@
#define FDCAN_IT_GROUP_RX_FIFO1 (FDCAN_ILS_RF1NL | FDCAN_ILS_RF1FL | FDCAN_ILS_RF1LL)
#endif

// 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)

// also defined in <PROC>_hal_fdcan.c, but not able to declare extern and reach the variable
static const uint8_t DLCtoBytes[] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 12, 16, 20, 24, 32, 48, 64};
const uint8_t DLCtoBytes[16] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 12, 16, 20, 24, 32, 48, 64};

bool can_init(pyb_can_obj_t *can_obj, uint32_t mode, uint32_t prescaler, uint32_t sjw, uint32_t bs1, uint32_t bs2, bool auto_restart) {
(void)auto_restart;

FDCAN_InitTypeDef *init = &can_obj->can.Init;
init->FrameFormat = FDCAN_FRAME_CLASSIC;
// Configure FDCAN with FD frame and BRS support.
init->FrameFormat = FDCAN_FRAME_FD_BRS;
init->Mode = mode;

init->NominalPrescaler = prescaler; // tq = NominalPrescaler x (1/fdcan_ker_ck)
Expand All @@ -81,46 +86,58 @@ bool can_init(pyb_can_obj_t *can_obj, uint32_t mode, uint32_t prescaler, uint32_
init->DataSyncJumpWidth = 1;
init->DataTimeSeg1 = 1;
init->DataTimeSeg2 = 1;
#endif

#if defined(STM32H7)
// variable used to specify RAM address in HAL, only for H7, G4 uses defined offset address in HAL
// The Message RAM is shared between CAN1 and CAN2. Setting the offset to half
// the Message RAM for the second CAN and using half the resources for each CAN.
init->StdFiltersNbr = 28; // /2 ? if FDCAN2 is used !!?
init->ExtFiltersNbr = 0; // Not used
init->TxFifoQueueMode = FDCAN_TX_FIFO_OPERATION;
#elif defined(STM32H7)
// 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,
// the maximum words per FDCAN instance is 1280 32-bit words.
if (can_obj->can_id == PYB_CAN_1) {
init->MessageRAMOffset = 0;
} else {
init->MessageRAMOffset = 2560 / 2;
init->MessageRAMOffset = FDCAN_MESSAGE_RAM_SIZE / 2;
}
#endif

#if defined(STM32G4)

init->StdFiltersNbr = 28; // /2 ? if FDCAN2 is used !!?
init->ExtFiltersNbr = 0; // Not used

#elif defined(STM32H7)

init->StdFiltersNbr = 64; // 128 / 2
init->ExtFiltersNbr = 0; // Not used

init->TxEventsNbr = 16; // 32 / 2
init->RxBuffersNbr = 32; // 64 / 2
init->TxBuffersNbr = 16; // 32 / 2

init->RxFifo0ElmtsNbr = 64; // 128 / 2
init->RxFifo0ElmtSize = FDCAN_DATA_BYTES_8;

init->RxFifo1ElmtsNbr = 64; // 128 / 2
init->RxFifo1ElmtSize = FDCAN_DATA_BYTES_8;

init->TxFifoQueueElmtsNbr = 16; // Tx fifo elements
init->TxElmtSize = FDCAN_DATA_BYTES_8;
// An element stored in the Message RAM contains an identifier, DLC, control bits, the
// data field and the specific transmission or reception bits field for control.
// The following code configures the different Message RAM sections per FDCAN instance.

// 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.
init->StdFiltersNbr = 64;
// Note extended identifiers are Not used in pyb_can.c and Not handled correctly.
// Disable the extended identifiers filters for now until this is fixed properly.
init->ExtFiltersNbr = 0 /*31*/;

// The Tx event FIFO is used to store the message ID and the timestamp of successfully
// transmitted elements. The Tx event FIFO can store a maximum of 32 (2 words) elements.
// NOTE: Events are stored in Tx event FIFO only if tx_msg.TxEventFifoControl is enabled.
init->TxEventsNbr = 0;

// Transmission section is configured in FIFO mode operation, with no dedicated Tx buffers.
// The Tx FIFO can store a maximum of 32 elements (or 576 words), each element is 18 words
// long (to support a maximum of 64 bytes data field):
// 2 words header + 16 words data field (to support up to 64 bytes of data).
// The total number of words reserved for the Tx FIFO per FDCAN instance is 288 words.
init->TxBuffersNbr = 0;
init->TxFifoQueueElmtsNbr = 16;
init->TxElmtSize = FDCAN_DATA_BYTES_64;
init->TxFifoQueueMode = FDCAN_TX_FIFO_OPERATION;

// Reception section is configured to use Rx FIFO 0 and Rx FIFO1, with no dedicated Rx buffers.
// Each Rx FIFO can store a maximum of 64 elements (1152 words), each element is 18 words
// long (to support a maximum of 64 bytes data field):
// 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->RxFifo0ElmtsNbr = 24;
init->RxFifo0ElmtSize = FDCAN_DATA_BYTES_64;
init->RxFifo1ElmtsNbr = 24;
init->RxFifo1ElmtSize = FDCAN_DATA_BYTES_64;
#endif

init->TxFifoQueueMode = FDCAN_TX_FIFO_OPERATION;

FDCAN_GlobalTypeDef *CANx = NULL;
const pin_obj_t *pins[2];

Expand Down Expand Up @@ -159,7 +176,10 @@ bool can_init(pyb_can_obj_t *can_obj, uint32_t mode, uint32_t prescaler, uint32_

// init CANx
can_obj->can.Instance = CANx;
HAL_FDCAN_Init(&can_obj->can);
// catch bad configuration errors.
if (HAL_FDCAN_Init(&can_obj->can) != HAL_OK) {
return false;
}

// Disable acceptance of non-matching frames (enabled by default)
HAL_FDCAN_ConfigGlobalFilter(&can_obj->can, FDCAN_REJECT, FDCAN_REJECT, DISABLE, DISABLE);
Expand All @@ -168,7 +188,7 @@ bool can_init(pyb_can_obj_t *can_obj, uint32_t mode, uint32_t prescaler, uint32_
HAL_FDCAN_Start(&can_obj->can);

// Reset all filters
for (int f = 0; f < 64; ++f) {
for (int f = 0; f < init->StdFiltersNbr; ++f) {
can_clearfilter(can_obj, f, 0);
}

Expand Down Expand Up @@ -299,10 +319,12 @@ int can_receive(FDCAN_HandleTypeDef *can, int fifo, FDCAN_RxHeaderTypeDef *hdr,
hdr->FDFormat = *address & FDCAN_ELEMENT_MASK_FDF;
hdr->FilterIndex = (*address & FDCAN_ELEMENT_MASK_FIDX) >> 24;
hdr->IsFilterMatchingFrame = (*address++ & FDCAN_ELEMENT_MASK_ANMF) >> 31;
// Convert DLC to Bytes.
hdr->DataLength = DLCtoBytes[hdr->DataLength];

// Copy data
uint8_t *pdata = (uint8_t *)address;
for (uint32_t i = 0; i < DLCtoBytes[hdr->DataLength]; ++i) {
for (uint32_t i = 0; i < hdr->DataLength; ++i) {
*data++ = *pdata++;
}

Expand Down
133 changes: 91 additions & 42 deletions ports/stm32/pyb_can.c
View file
Expand Up @@ -42,6 +42,7 @@
#if MICROPY_HW_ENABLE_FDCAN

#define CAN_MAX_FILTER (64)
#define CAN_MAX_DATA_FRAME (64)

#define CAN_FIFO0 FDCAN_RX_FIFO0
#define CAN_FIFO1 FDCAN_RX_FIFO1
Expand Down Expand Up @@ -89,10 +90,11 @@

// Both banks start at 0
STATIC uint8_t can2_start_bank = 0;

extern const uint8_t DLCtoBytes[16];
#else

#define CAN_MAX_FILTER (28)
#define CAN_MAX_DATA_FRAME (8)

#define CAN_DEFAULT_PRESCALER (100)
#define CAN_DEFAULT_SJW (1)
Expand Down Expand Up @@ -180,19 +182,50 @@ STATIC uint32_t pyb_can_get_source_freq() {
return can_kern_clk;
}

STATIC void pyb_can_get_bit_timing(mp_uint_t baudrate, mp_uint_t sample_point,
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++) {
if ((baudrate == (can_kern_clk / (brp * (1 + bs1 + bs2)))) &&
((sample_point * 10) == (((1 + bs1) * 1000) / (1 + bs1 + bs2)))) {
*bs1_out = bs1;
*bs2_out = bs2;
*prescaler_out = brp;
return;
}
}
}
}

mp_raise_msg(&mp_type_ValueError, MP_ERROR_TEXT("couldn't match baudrate and sample point"));
}

// init(mode, extframe=False, prescaler=100, *, sjw=1, bs1=6, bs2=8)
STATIC mp_obj_t pyb_can_init_helper(pyb_can_obj_t *self, size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
enum { ARG_mode, ARG_extframe, ARG_prescaler, ARG_sjw, ARG_bs1, ARG_bs2, ARG_auto_restart, ARG_baudrate, ARG_sample_point };
enum { ARG_mode, ARG_extframe, ARG_prescaler, ARG_sjw, ARG_bs1, ARG_bs2, ARG_auto_restart, ARG_baudrate, ARG_sample_point,
ARG_brs_prescaler, ARG_brs_sjw, ARG_brs_bs1, ARG_brs_bs2, ARG_brs_baudrate, ARG_brs_sample_point };
static const mp_arg_t allowed_args[] = {
{ MP_QSTR_mode, MP_ARG_REQUIRED | MP_ARG_INT, {.u_int = CAN_MODE_NORMAL} },
{ MP_QSTR_extframe, MP_ARG_BOOL, {.u_bool = false} },
{ MP_QSTR_prescaler, MP_ARG_INT, {.u_int = CAN_DEFAULT_PRESCALER} },
{ MP_QSTR_sjw, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = CAN_DEFAULT_SJW} },
{ MP_QSTR_bs1, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = CAN_DEFAULT_BS1} },
{ MP_QSTR_bs2, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = CAN_DEFAULT_BS2} },
{ MP_QSTR_auto_restart, MP_ARG_KW_ONLY | MP_ARG_BOOL, {.u_bool = false} },
{ MP_QSTR_baudrate, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 0} },
{ MP_QSTR_sample_point, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 75} }, // 75% sampling point
{ MP_QSTR_mode, MP_ARG_REQUIRED | MP_ARG_INT, {.u_int = CAN_MODE_NORMAL} },
{ MP_QSTR_extframe, MP_ARG_BOOL, {.u_bool = false} },
{ MP_QSTR_prescaler, MP_ARG_INT, {.u_int = CAN_DEFAULT_PRESCALER} },
{ MP_QSTR_sjw, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = CAN_DEFAULT_SJW} },
{ MP_QSTR_bs1, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = CAN_DEFAULT_BS1} },
{ MP_QSTR_bs2, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = CAN_DEFAULT_BS2} },
{ MP_QSTR_auto_restart, MP_ARG_KW_ONLY | MP_ARG_BOOL, {.u_bool = false} },
{ MP_QSTR_baudrate, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 0} },
{ MP_QSTR_sample_point, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 75} }, // 75% sampling point
#if MICROPY_HW_ENABLE_FDCAN
{ MP_QSTR_brs_prescaler, MP_ARG_INT, {.u_int = CAN_DEFAULT_PRESCALER} },
{ MP_QSTR_brs_sjw, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = CAN_DEFAULT_SJW} },
{ MP_QSTR_brs_bs1, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = CAN_DEFAULT_BS1} },
{ MP_QSTR_brs_bs2, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = CAN_DEFAULT_BS2} },
{ MP_QSTR_brs_baudrate, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 0} },
{ MP_QSTR_brs_sample_point, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 0} }
#endif
};

// parse args
Expand All @@ -206,34 +239,30 @@ STATIC mp_obj_t pyb_can_init_helper(pyb_can_obj_t *self, size_t n_args, const mp

// Calculate CAN bit timing from baudrate if provided
if (args[ARG_baudrate].u_int != 0) {
uint32_t baudrate = args[ARG_baudrate].u_int;
uint32_t sampoint = args[ARG_sample_point].u_int;
uint32_t can_kern_clk = pyb_can_get_source_freq();
bool timing_found = false;

// The following max values work on all MCUs for classical CAN.
for (int brp = 1; brp < 512 && !timing_found; brp++) {
for (int bs1 = 1; bs1 < 16 && !timing_found; bs1++) {
for (int bs2 = 1; bs2 < 8 && !timing_found; bs2++) {
if ((baudrate == (can_kern_clk / (brp * (1 + bs1 + bs2)))) &&
((sampoint * 10) == (((1 + bs1) * 1000) / (1 + bs1 + bs2)))) {
args[ARG_bs1].u_int = bs1;
args[ARG_bs2].u_int = bs2;
args[ARG_prescaler].u_int = brp;
timing_found = true;
}
}
}
}
if (!timing_found) {
mp_raise_msg(&mp_type_ValueError, MP_ERROR_TEXT("couldn't match baudrate and sample point"));
}
pyb_can_get_bit_timing(args[ARG_baudrate].u_int, args[ARG_sample_point].u_int,
&args[ARG_bs1].u_int, &args[ARG_bs2].u_int, &args[ARG_prescaler].u_int);
}

// init CAN (if it fails, it's because the port doesn't exist)
#if MICROPY_HW_ENABLE_FDCAN
// If no sample point is provided for data bit timing, use the nominal sample point.
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
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,
&args[ARG_brs_bs1].u_int, &args[ARG_brs_bs2].u_int, &args[ARG_brs_prescaler].u_int);
}
// Set BRS bit timings.
self->can.Init.DataPrescaler = args[ARG_brs_prescaler].u_int;
self->can.Init.DataSyncJumpWidth = args[ARG_brs_sjw].u_int;
self->can.Init.DataTimeSeg1 = args[ARG_bs1].u_int; // DataTimeSeg1 = Propagation_segment + Phase_segment_1
self->can.Init.DataTimeSeg2 = args[ARG_bs2].u_int;
#endif

if (!can_init(self, args[ARG_mode].u_int, args[ARG_prescaler].u_int, args[ARG_sjw].u_int,
args[ARG_bs1].u_int, args[ARG_bs2].u_int, args[ARG_auto_restart].u_bool)) {
mp_raise_msg_varg(&mp_type_ValueError, MP_ERROR_TEXT("CAN(%d) doesn't exist"), self->can_id);
mp_raise_msg_varg(&mp_type_ValueError, MP_ERROR_TEXT("CAN(%d) init failure"), self->can_id);
}

return mp_const_none;
Expand Down Expand Up @@ -450,12 +479,16 @@ STATIC MP_DEFINE_CONST_FUN_OBJ_2(pyb_can_any_obj, pyb_can_any);

// send(send, addr, *, timeout=5000)
STATIC mp_obj_t pyb_can_send(size_t n_args, const mp_obj_t *pos_args, mp_map_t *kw_args) {
enum { ARG_data, ARG_id, ARG_timeout, ARG_rtr };
enum { ARG_data, ARG_id, ARG_timeout, ARG_rtr, ARG_fdf, ARG_brs };
static const mp_arg_t allowed_args[] = {
{ MP_QSTR_data, MP_ARG_REQUIRED | MP_ARG_OBJ, {.u_obj = MP_OBJ_NULL} },
{ MP_QSTR_id, MP_ARG_REQUIRED | MP_ARG_INT, {.u_int = 0} },
{ MP_QSTR_timeout, MP_ARG_KW_ONLY | MP_ARG_INT, {.u_int = 0} },
{ MP_QSTR_rtr, MP_ARG_KW_ONLY | MP_ARG_BOOL, {.u_bool = false} },
#if MICROPY_HW_ENABLE_FDCAN
{ MP_QSTR_fdf, MP_ARG_KW_ONLY | MP_ARG_BOOL, {.u_bool = false} },
{ MP_QSTR_brs, MP_ARG_KW_ONLY | MP_ARG_BOOL, {.u_bool = false} },
#endif
};

// parse args
Expand All @@ -468,21 +501,20 @@ STATIC mp_obj_t pyb_can_send(size_t n_args, const mp_obj_t *pos_args, mp_map_t *
uint8_t data[1];
pyb_buf_get_for_send(args[ARG_data].u_obj, &bufinfo, data);

if (bufinfo.len > 8) {
if (bufinfo.len > CAN_MAX_DATA_FRAME) {
mp_raise_ValueError(MP_ERROR_TEXT("CAN data field too long"));
}

// send the data
CanTxMsgTypeDef tx_msg;

#if MICROPY_HW_ENABLE_FDCAN
uint8_t tx_data[8];
uint8_t tx_data[CAN_MAX_DATA_FRAME];
memset(tx_data, 0, sizeof(tx_data));

tx_msg.MessageMarker = 0;
tx_msg.ErrorStateIndicator = FDCAN_ESI_ACTIVE;
tx_msg.BitRateSwitch = FDCAN_BRS_OFF;
tx_msg.FDFormat = FDCAN_CLASSIC_CAN;
tx_msg.TxEventFifoControl = FDCAN_NO_TX_EVENTS;
tx_msg.DataLength = (bufinfo.len << 16); // TODO DLC for len > 8

if (self->extframe) {
tx_msg.Identifier = args[ARG_id].u_int & 0x1FFFFFFF;
Expand All @@ -496,6 +528,23 @@ STATIC mp_obj_t pyb_can_send(size_t n_args, const mp_obj_t *pos_args, mp_map_t *
} else {
tx_msg.TxFrameType = FDCAN_REMOTE_FRAME;
}
if (args[ARG_fdf].u_bool == false) {
tx_msg.FDFormat = FDCAN_CLASSIC_CAN;
} else {
tx_msg.FDFormat = FDCAN_FD_CAN;
}
if (args[ARG_brs].u_bool == false) {
tx_msg.BitRateSwitch = FDCAN_BRS_OFF;
} else {
tx_msg.BitRateSwitch = FDCAN_BRS_ON;
}
// Roundup DataLength to next DLC size and encode to DLC.
for (mp_uint_t i = 0; i < MP_ARRAY_SIZE(DLCtoBytes); i++) {
if (bufinfo.len <= DLCtoBytes[i]) {
tx_msg.DataLength = (i << 16);
break;
}
}
#else
tx_msg.DLC = bufinfo.len;
uint8_t *tx_data = tx_msg.Data; // Data is uint32_t but holds only 1 byte
Expand Down Expand Up @@ -565,7 +614,7 @@ STATIC mp_obj_t pyb_can_recv(size_t n_args, const mp_obj_t *pos_args, mp_map_t *
// receive the data
CanRxMsgTypeDef rx_msg;
#if MICROPY_HW_ENABLE_FDCAN
uint8_t rx_data[8];
uint8_t rx_data[CAN_MAX_DATA_FRAME];
#else
uint8_t *rx_data = rx_msg.Data;
#endif
Expand Down

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