ESP32 Forum

I am not familiar with that chip, and Google yields no datasheets; do you have a link with more info about it?

I think he means SN65HVD230

Ah. In that case, I don't know. It looks like you can mash the two together, but my knowledge of CAN is too limited to say for sure.

Update.
Now the driver calculates the baud rate prescaler based on the APB clock and I added a few more baud rates. (requires math.h)

CAN_Init

Code: Select all

intCAN_init(){

	//Time quantum
	double __tq = 0;

	//Bit timing
	float __bt = 1000/CAN_cfg.speed;

    //enable module
    SET_PERI_REG_MASK(DPORT_PERIP_CLK_EN_REG, DPORT_CAN_CLK_EN);
    CLEAR_PERI_REG_MASK(DPORT_PERIP_RST_EN_REG, DPORT_CAN_RST);

    //configure TX pin
    gpio_set_direction(CAN_cfg.tx_pin_id,GPIO_MODE_OUTPUT);
    gpio_matrix_out(CAN_cfg.tx_pin_id,CAN_TX_IDX,0,0);
    gpio_pad_select_gpio(CAN_cfg.tx_pin_id);

    //configure RX pin
	gpio_set_direction(CAN_cfg.rx_pin_id,GPIO_MODE_INPUT);
	gpio_matrix_in(CAN_cfg.rx_pin_id,CAN_RX_IDX,0);
	gpio_pad_select_gpio(CAN_cfg.rx_pin_id);

    //set to PELICAN mode
	MODULE_CAN->CDR.B.CAN_M=0x1;

	//synchronization jump width is the same for all baud rates
	MODULE_CAN->BTR0.B.SJW		=0x1;

	//TSEG2 is the same for all baud rates
	MODULE_CAN->BTR1.B.TSEG2	=0x1;

	//select time quantum and set TSEG1
	switch(CAN_cfg.speed){
		case CAN_SPEED_1000KBPS:
			MODULE_CAN->BTR1.B.TSEG1	=0x4;
			__tq = 0.125;
			break;

		case CAN_SPEED_800KBPS:
			MODULE_CAN->BTR1.B.TSEG1	=0x6;
			__tq = 0.125;
			break;
		default:
			MODULE_CAN->BTR1.B.TSEG1	=0xc;
			__tq = __bt / 16;
	}

	//set baud rate prescaler
	MODULE_CAN->BTR0.B.BRP=(uint8_t)round((((APB_CLK_FREQ * __tq) / 2) - 1)/1000000)-1;

    /* Set sampling
     * 1 -> triple; the bus is sampled three times; recommended for low/medium speed buses     (class A and B) where filtering spikes on the bus line is beneficial
     * 0 -> single; the bus is sampled once; recommended for high speed buses (SAE class C)*/
    MODULE_CAN->BTR1.B.SAM	=0x1;

    //enable all interrupts
    MODULE_CAN->IER.U = 0xff;

    //no acceptance filtering, as we want to fetch all messages
    MODULE_CAN->MBX_CTRL.ACC.CODE[0] = 0;
    MODULE_CAN->MBX_CTRL.ACC.CODE[1] = 0;
    MODULE_CAN->MBX_CTRL.ACC.CODE[2] = 0;
    MODULE_CAN->MBX_CTRL.ACC.CODE[3] = 0;
    MODULE_CAN->MBX_CTRL.ACC.MASK[0] = 0xff;
    MODULE_CAN->MBX_CTRL.ACC.MASK[1] = 0xff;
    MODULE_CAN->MBX_CTRL.ACC.MASK[2] = 0xff;
    MODULE_CAN->MBX_CTRL.ACC.MASK[3] = 0xff;

    //set to normal mode
    MODULE_CAN->OCR.B.OCMODE=__CAN_OC_NOM;

    //clear error counters
    MODULE_CAN->TXERR.U = 0;
    MODULE_CAN->RXERR.U = 0;
    (void)MODULE_CAN->ECC;

    //clear interrupt flags
    (void)MODULE_CAN->IR.U;

    //install CAN ISR
    esp_intr_alloc(ETS_CAN_INTR_SOURCE,0,CAN_isr,NULL,NULL);

    //Showtime. Release Reset Mode.
    MODULE_CAN->MOD.B.RM = 0;

    return 0;
}

Configuration

Code: Select all

/** \brief CAN Node Bus speed */
typedef enum  {
	CAN_SPEED_100KBPS=100, 				/**< \brief CAN Node runs at 100kBit/s. */
	CAN_SPEED_125KBPS=125, 				/**< \brief CAN Node runs at 125kBit/s. */
	CAN_SPEED_250KBPS=250, 				/**< \brief CAN Node runs at 250kBit/s. */
	CAN_SPEED_500KBPS=500, 				/**< \brief CAN Node runs at 500kBit/s. */
	CAN_SPEED_800KBPS=800, 				/**< \brief CAN Node runs at 800kBit/s. */
	CAN_SPEED_1000KBPS=1000				/**< \brief CAN Node runs at 1000kBit/s. */
}CAN_speed_t;

/** \brief CAN configuration structure */
typedef struct  {
   CAN_speed_t         speed;         /**< \brief CAN speed. */
    gpio_num_t          tx_pin_id;      /**< \brief TX pin. */
    gpio_num_t          rx_pin_id;      /**< \brief RX pin. */
    QueueHandle_t       rx_queue;      /**< \brief Handler to FreeRTOS RX queue. */
}CAN_device_t;

extern CAN_device_t CAN_cfg;

CAN_device_t CAN_cfg = {
   .speed=CAN_SPEED_500KBPS,
   .tx_pin_id = GPIO_NUM_5,
   .rx_pin_id = GPIO_NUM_4,
   .rx_queue=NULL,
};

You wouldn't happen to have an example do you? I am using an MCP2551 transceiver but it should all work the same.

I also use the MCP2551.
An example is planned but currently im drowning in work...

I also use the MCP2551.
An example is planned but currently im drowning in work...

No problem! I was able to get this working The code provided was perfect - I just needed to wire up my MCP2551 correctly.

great!

I will try my best to upload an example next week

An example project now can be found on:
http://www.barth-dev.de/can-driver-esp32/

Sorry, I meant SN65HVD230DR from Texas Instrument.

http://www.ti.com/lit/ds/symlink/sn65hvd232.pdf

Those transceivers work all the same way, by translating the bus level to logical level.
Basically you only need to check if the transceiver supports your baud-rate.

(of course there are other parameters of the chip [like the package to pick something obvious] but that is nothing you have to deal with [at least I think so ])

Hi group, hi Thomas,
I'm struggling now days since you give demo of your code..
I try first with change of baud rate to 250k to used with my another project. Through transceiver I getting nice signal of frames on RX pin but from ESP32 non of response. Then I try sending frame but again noting on TX pin. I pass through your cod few times and I don't see some problems. Today I tried baud 500k how "Pawel Szabaciuk" said that it's work in his case, but again in my case not .
Do you have some tip?
Thanks,
Dejan