TWI I2C problem ( ssd1306 display )

RE: TWI I2C problem ( ssd1306 display )

Kenneth — Mon, 09 Apr 2018 15:33:16 GMT

Without a 100ms delay you would like have problems with nrf_drv_twi_tx() be called multiple times in the while() loop, another transaction can be buffered while the first is executing. Also make sure that all variables are alive in the scope, so you don't exit ssd1306_command() before nrf_drv_twi_tx() is completed, which may be the case here since you are potentially calling nrf_drv_twi_tx() multiple times.

RE: TWI I2C problem ( ssd1306 display )

Pawel Trznadel — Fri, 06 Apr 2018 11:54:28 GMT

I think that I should be more specific about ssd1306_begin() function which I'm use in my project. The function looks like this:

void ssd1306_begin(uint8_t vccstate, uint8_t i2caddr, bool reset)
{
    _vccstate = vccstate;
    _i2caddr = i2caddr;
    UNUSED_VARIABLE(_i2caddr);

    _width = WIDTH = SSD1306_LCDWIDTH;
    _height = HEIGHT = SSD1306_LCDHEIGHT;

    cursor_y  = cursor_x    = 0;
    textsize  = 1;
    textcolor = textbgcolor = 0xFFFF;
    wrap      = true;
    _cp437    = false;

    rotation  = 0;
		
    // Init sequence for 128x32 OLED module
    ssd1306_command(SSD1306_DISPLAYOFF);                    // 0xAE
    ssd1306_command(SSD1306_SETDISPLAYCLOCKDIV);            // 0xD5
    ssd1306_command(0x80);                                  // the suggested ratio 0x80

    ssd1306_command(SSD1306_SETMULTIPLEX);                  // 0xA8
    ssd1306_command(0x1F);
    ssd1306_command(SSD1306_SETDISPLAYOFFSET);              // 0xD3
    ssd1306_command(0x00);                                   // no offset
    ssd1306_command(SSD1306_SETSTARTLINE | 0x0);            // line #0
    ssd1306_command(SSD1306_CHARGEPUMP);                    // 0x8D
    if (vccstate == SSD1306_EXTERNALVCC) {
        ssd1306_command(0x10);
    }
    else {
        ssd1306_command(0x14);
    }
    ssd1306_command(SSD1306_MEMORYMODE);                    // 0x20
    ssd1306_command(0x0);                                  // 0x0 act like ks0108
    ssd1306_command(SSD1306_SEGREMAP | 0x1);
    ssd1306_command(SSD1306_COMSCANDEC);
    ssd1306_command(SSD1306_SETCOMPINS);                    // 0xDA
    ssd1306_command(0x02);
    ssd1306_command(SSD1306_SETCONTRAST);                   // 0x81
    ssd1306_command(0x8F);
    ssd1306_command(SSD1306_SETPRECHARGE);                  // 0xd9
    if (vccstate == SSD1306_EXTERNALVCC) {
        ssd1306_command(0x22);
    }
    else {
        ssd1306_command(0xF1);
    }
    ssd1306_command(SSD1306_SETVCOMDETECT);                 // 0xDB
    ssd1306_command(0x40);
    ssd1306_command(SSD1306_DISPLAYALLON_RESUME);           // 0xA4
    ssd1306_command(SSD1306_NORMALDISPLAY);                 // 0xA6
    ssd1306_command(SSD1306_DISPLAYON);//--turn on oled panel
}

As you can see there is more then one ssd1306_command() function about which I've mentioned above.

Right now I've changed ssd1306_command() function to be able to printf error code. I put here also nrf_delay_ms(100) because otherwise APP_ERROR_CHECK(ret) has reset my app befor error was printed:

void ssd1306_command(uint8_t c)
{
        ret_code_t ret;
        uint8_t dta_send[] = {0x00, c};
				bool no_stop = false;
				
				m_xfer_done = false;
				while(!m_xfer_done){
					ret = nrf_drv_twi_tx(&m_twi_master, _i2caddr, dta_send, sizeof(dta_send), no_stop);
					printf("error code:0x%x.\r\n", ret);
					nrf_delay_ms(100);
					APP_ERROR_CHECK(ret);
				}
        UNUSED_VARIABLE(ret);
}

Reason why I write about this is fact that when i call ssd1306_command() only once in ssd1306_begin() function, returned error code from nrf_drv_twi_tx() is 0x00, which means NRF_SUCCESS. Unfortunately every next call of ssd1306_command() (which include nrf_drv_twi_tx() ) cause 0x11 error code - NRF_ERROR_INVALID_ADDR.
Has anyone idea where is the problem?

RE: TWI I2C problem ( ssd1306 display )

Pawel Trznadel — Thu, 05 Apr 2018 15:07:01 GMT

Unfortunately removal of hard coded values didn't help 😞
In my code only const argument in nrf_drv_twi_tx() function is TWI instance

static const nrf_drv_twi_t m_twi_master = NRF_DRV_TWI_INSTANCE(0);

RE: TWI I2C problem ( ssd1306 display )

Kenneth — Thu, 05 Apr 2018 13:37:23 GMT

Typically if for instance any of the parameters are of 'const' type they may be placed in flash, not RAM. Also hard coded values, like the parameter value '2' may be stored in flash here. This will cause problem, so instead use a variable length = 2, and then use length variable as input parameter.

RE: TWI I2C problem ( ssd1306 display )

Pawel Trznadel — Thu, 05 Apr 2018 09:12:59 GMT

I'm afraid I'm not able to give an answer for your question. Could you specified when exactly this arguments will be not in RAM?

RE: TWI I2C problem ( ssd1306 display )

Kenneth — Thu, 05 Apr 2018 08:33:32 GMT

Error code 11 (=NRF_ERROR_INVALID_ADDR) from nrf_drv_twi_tx() means "If the EasyDMA is used and memory adress in not in RAM." Are you sure all parameters (pointers, values, data and addresses) here is in RAM, and not flash when calling nrf_drv_twi_tx()?

RE: TWI I2C problem ( ssd1306 display )

Pawel Trznadel — Wed, 04 Apr 2018 20:32:33 GMT

Yes I've tried twi_scanner it returns correct i2c address as shown below:

<info> app: TWI scanner.
<info> app: TWI device detected at address 0x3C.

Unfortunately I don't have logic analyzer to monitor the SCL and SDA lines.

It seems that I'm not receiving NRF_DRV_TWI_EVT_ADDRESS_NACK or NRF_DRV_TWI_EVT_DATA_NACK events either.

I've just printf error code returned from nrf_drv_twi_tx() function, and it is 0x11, but unfortunately I've no idea what does it mean :( Have you any idea which of the error from this list match with my error number?

 * @retval NRF_SUCCESS                  If the procedure was successful.
 * @retval NRF_ERROR_BUSY               If the driver is not ready for a new transfer.
 * @retval NRF_ERROR_INTERNAL           If an error was detected by hardware.
 * @retval NRF_ERROR_INVALID_ADDR       If the EasyDMA is used and memory adress in not in RAM.
 * @retval NRF_ERROR_DRV_TWI_ERR_ANACK  If NACK received after sending the address in polling mode.
 * @retval NRF_ERROR_DRV_TWI_ERR_DNACK  If NACK received after sending a data byte in polling mode.

RE: TWI I2C problem ( ssd1306 display )

Kenneth — Wed, 04 Apr 2018 08:29:06 GMT

Hi,

Have you first tried: \nRF5_SDK_14.2.0_17b948a\examples\peripheral\twi_scanner?

Do you have a logic analyzer plot showing the SCL and SDA lines?

Do you have other events such as NRF_DRV_TWI_EVT_ADDRESS_NACK or NRF_DRV_TWI_EVT_DATA_NACK instead of NRF_DRV_TWI_EVT_DONE?