SPI InstrFetchProhibited

[schmm2]

Good Evening

My target: Control an ePaper Display via SPI.
I'm using: ESP32 Core Board V2, WaveShare 1.54 ePaper ssd1607
Environment: esp-idf, not arduino

I know there are already libraries available, but I want to understand how it works technically.
I downloaded the sample of the manufacturer for Arduino. Now I'm trying to port that stuff to ESP32, analyze and learn.
So far I'm pretty happy with the result

I'm almost done but I run into an issue:
As soon as the code executes spi_device_transmit I get a Guru Meditation Error of type InstrFetchProhibited
and the ESP32 reboots.

One part of the code:

Code: Select all

void EpdIf::SpiTransfer(unsigned char data){
	// dc pin handled externaly
	gpio_set_level((gpio_num_t)CS_PIN, LOW);	
	// SPI Transfer
	spi_transaction_t t;
	memset(&t, 0, sizeof(t));       //Zero out the transaction
	t.length=8;                     //Command is 8 bits
	t.tx_buffer=&data;               //The data
	ret=spi_device_transmit(spi, &t);  //Transmit!
	assert(ret==ESP_OK);
	gpio_set_level((gpio_num_t)CS_PIN, HIGH);
}

int EpdIf::IfInit(void) {
	gpio_set_direction((gpio_num_t)PIN_CS, GPIO_MODE_OUTPUT);
        gpio_set_direction((gpio_num_t)PIN_RESET, GPIO_MODE_OUTPUT);
	gpio_set_direction((gpio_num_t)PIN_DC, GPIO_MODE_OUTPUT);
	gpio_set_direction((gpio_num_t)PIN_MOSI, GPIO_MODE_OUTPUT);
	gpio_set_direction((gpio_num_t)PIN_BUSY, GPIO_MODE_INPUT);
	
	spi_bus_config_t buscfg;
	buscfg.miso_io_num = -1;
	buscfg.mosi_io_num = PIN_MOSI;
	buscfg.sclk_io_num = PIN_CLK;
	buscfg.quadwp_io_num = -1;
	buscfg.quadhd_io_num = -1;
	buscfg.max_transfer_sz = 5*1024;
	
	spi_device_interface_config_t dev_config;
	dev_config.mode             = 0;
	dev_config.cs_ena_posttrans = 0;
	dev_config.cs_ena_pretrans  = 0;
	dev_config.clock_speed_hz   = 10*1000*1000;
	dev_config.spics_io_num     = PIN_CS;
	dev_config.flags            = 0;
	dev_config.queue_size       = 7;
	
	//Initialize the SPI bus
	ret=spi_bus_initialize(HSPI_HOST, &buscfg, 1);
	printf("SPI: bus initialization done\r\n");
	assert(ret==ESP_OK);
	
	//Attach the display
	ret=spi_bus_add_device(HSPI_HOST, &dev_config, &spi);
	printf("SPI: display device added to spi bus (%d)\r\n", HSPI_HOST);
	assert(ret==ESP_OK);
		
	return 0;
}

Init main function:

Code: Select all

int Epd::Init(const unsigned char* lut) {
    printf("epd1n54: Init start\r\n");
	
	/* this calls the peripheral hardware interface, see epdif */
    if (IfInit() != 0) {
        printf("epd1n54: init error\r\n");
		return -1;
    }
    /* EPD hardware init start */
    printf("epd1n54: Init done\r\n");
	
   this->lut = lut;
    Reset();
    SendCommand(DRIVER_OUTPUT_CONTROL);
    SendData((EPD_HEIGHT - 1) & 0xFF);
    SendData(((EPD_HEIGHT - 1) >> 8) & 0xFF);
    SendData(0x00);                     // GD = 0; SM = 0; TB = 0;
    SendCommand(BOOSTER_SOFT_START_CONTROL);
    SendData(0xD7);
    SendData(0xD6);
    SendData(0x9D);
    SendCommand(WRITE_VCOM_REGISTER);
    SendData(0xA8);                     // VCOM 7C
    SendCommand(SET_DUMMY_LINE_PERIOD);
    SendData(0x1A);                     // 4 dummy lines per gate
    SendCommand(SET_GATE_TIME);
    SendData(0x08);                     // 2us per line
    SendCommand(DATA_ENTRY_MODE_SETTING);
    SendData(0x03);                     // X increment; Y increment
    SetLut(this->lut);
    /* EPD hardware init end */
    return 0;
}

I'm using these pins:

Code: Select all

// CLK - GPIO 18
#define PIN_CLK 18 // yellow

// MOSI - GPIO 23
#define PIN_MOSI 23 // blue

// RESET - GPIO 16
#define PIN_RESET 16 // white

// DC - GPIO 17
#define PIN_DC 17 // green

// CS - GPIO 5
#define PIN_CS 5 // orange

// Busy - GPIO 4
#define PIN_BUSY 4 // violett

Does anybody have an idea why this reboot happens?
I thank you for your time, so far, this board has been an amazing help.
If I didn't provide all necessary informations, please let me know.

Greetings
Martin

[dieg0_]

hey, could you resolve the issue. If so, please share... I am stuck, too

[ESP_Sprite]

You allocate your busconfig and devconfig on the stack, causing them by default to be filled with garbage, then don't fill in all the fields of the structure. There are callbacks in there, and not filling them in will cause the callback to go into random address space, causing the exception.

Change the places where you initialize the configs to e.g.

Code: Select all

spi_bus_config_t buscfg={};

to fill the structs with 0, and everything should work.

[dieg0_]

thank you so much, the small things...