I2c oled screen not working

gobeng · December 28, 2022, 10:28pm

Which version of system do you use? Khadas official images, self built images, or others?

Khadas official image ubuntu server
uname
Linux
uname -r
5.4.180

Connected to i2cm_a and enabled the i2cm interface

Please describe your issue below:

I am trying to show data on a i2c oled display (https://www.amazon.co.uk/gp/product/B093KHHKVM/ref=ppx_yo_dt_b_asin_title_o04_s00?ie=UTF8&th=1) but I do not get anything on the screen. I am using the WiringPi library.

Below is the code I am using.

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>

#include <wiringPiI2C.h>
#include <wiringPi.h>

#include "lcd128x64.h"

#define DEVICE_ID 0x3C


int main (int argc, char **argv)
{
    // Setup I2C communication
    int fd = wiringPiI2CSetup(DEVICE_ID);
    if (fd == -1) {
        printf("Failed to init I2C communication.\n");
        return -1;
    }
    printf("I2C communication successfully setup.\n");

    fd = wiringPiI2CSetupInterface("/dev/i2c-0", 0x3C);
    if (fd == -1) {
        printf("Failed to set I2C interface.\n");
        return -1;
    }
    printf("I2C interface successfully setup.\n");

    while (1) {
        lcd128x64setup();
        lcd128x64clear(0);
    }

    return 0;
}

Post a console log of your issue below:

I2C communication successfully setup.
I2C interface successfully setup.

i2cdetect -y 0
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:                         -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- 3c -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
70: -- -- -- -- -- -- -- --

numbqq · December 29, 2022, 1:10am

Hello @gobeng

How about this one ?

#include <stdio.h>
#include <stdlib.h>
#include <stdint.h>

#include <wiringPiI2C.h>
#include <wiringPi.h>

#include "lcd128x64.h"

#define DEVICE_ID 0x3C


int main (int argc, char **argv)
{
    // Setup I2C communication
    int fd = wiringPiI2CSetupInterface("/dev/i2c-0", 0x3C);
    if (fd == -1) {
        printf("Failed to set I2C interface.\n");
        return -1;
    }
    printf("I2C interface successfully setup.\n");

    while (1) {
        lcd128x64setup();
        lcd128x64clear(0);
    }

    return 0;
}

gobeng · December 29, 2022, 2:33am

Hello @numbqq thanks for the quick reply
Made some changes as well but I am still not getting anything on the screen

int main (int argc, char **argv)
{
// Setup I2C communication
int fd = wiringPiI2CSetupInterface(“/dev/i2c-0”, 0x3C);
if (fd == -1) {
printf(“Failed to set I2C interface.\n”);
return -1;
}

printf("I2C interface successfully setup.\n");

int status = lcd128x64setup();
if (status != 0) {
    printf("Failed to set lcd.\n");
    return -1;
}
printf("LCD setup. \n");

while (1) {
    lcd128x64puts(4, 4, "Test\nThis\n", 1, 0);
}
return 0;

}

I have tried using the original lcd128x64.h built into the vim4

numbqq · December 29, 2022, 3:15am

Hello @gobeng

Please try to write and read one byte from the register to check wether the value is correct or not.

gobeng · December 29, 2022, 3:46am

Hello @numbqq
regardless of what I put I keep getting these numbers
fd before = 3
fd after = 3
status = 67

Code:

int main (int argc, char **argv)
{
    int fd = 0;
    int status = 0;

    // Setup I2C communication
    fd = wiringPiI2CSetupInterface("/dev/i2c-0", 0x3C);
    if (fd == -1) {
        printf("Failed to set I2C interface.\n");
        return -1;
    }
    printf("I2C interface successfully setup.\n");

    status = lcd128x64setup();
    if (status != 0) {
        printf("Failed to set lcd.\n");
        return -1;
        status = 0;
    }
    printf("LCD setup. \n");
    printf("fd before = %d \n", fd);

    wiringPiI2CWrite(fd, 4);

    status = wiringPiI2CRead(fd);

    printf("fd after = %d \n", fd);
    printf("status = %d \n", status);

    return 0;
}

gobeng · December 30, 2022, 1:43am

Hello @numbqq
I just found this out. Do you know what could be causing it?

root@vim4:~# cat /boot/overlays/kvim4.dtb.overlay.env
fdt_overlays=i2cm_a i2cm_f
root@vim4:~# gpio readall
 +------+-----+----------+------+---+----+----- Model Khadas VIM4 --+----+---+------+----------+-----+------+
 | GPIO | wPi |   Name   | Mode | V | DS | PU/PD | Physical | PU/PD | DS | V | Mode |   Name   | wPi | GPIO |
 +------+-----+----------+------+---+----+-------+----++----+-------+----+---+------+----------+-----+------+
 |      |     |       5V |      |   |    |       |  1 || 21 |       |    |   |      | GND      |     |      |
 |      |     |       5V |      |   |    |       |  2 || 22 | DSBLD |    | 1 | ALT0 | PIN.Y17  | 6   |  501 |
 |      |     |  HUB_D4N |      |   |    |       |  3 || 23 | DSBLD |    | 1 | ALT0 | PIN.Y18  | 7   |  502 |
 |      |     |  HUB_D4P |      |   |    |       |  4 || 24 |       |    |   |      | GND      |     |      |
 |      |     |      GND |      |   |    |       |  5 || 25 | DSBLD |    | 1 | ALT1 | PIN.T20  | 8   |  466 |
 |      |     |   VCCMCU |      |   |    |       |  6 || 26 | DSBLD |    | 1 | ALT1 | PIN.T21  | 9   |  467 |
 |      |     | MCUBOOT0 |      |   |    |       |  7 || 27 |       |    |   |      | 3V3      |     |      |
 |      |     | MCUSWDIO |      |   |    |       |  8 || 28 |       |    |   |      | GND      |     |      |
 |      |     |      GND |      |   |    |       |  9 || 29 | P/D   |    | 0 | IN   | PIN.T1   | 10  |  447 |
 |      |  19 |  ADC_CH6 |      |   |    |       | 10 || 30 | P/D   |    | 0 | IN   | PIN.T0   | 11  |  446 |
 |      |     |   VDD1V8 |      |   |    |       | 11 || 31 | P/D   |    | 0 | IN   | PIN.T3   | 12  |  449 |
 |      |  20 |  ADC_CH3 |      |   |    |       | 12 || 32 | P/D   |    | 0 | IN   | PIN.T2   | 13  |  448 |
 |  420 |   1 | SPDIFOUT |   IN | 0 |    |   P/D | 13 || 33 | P/D   |    | 0 | IN   | PIN.T4   | 14  |  450 |
 |      |     |      GND |      |   |    |       | 14 || 34 |       |    |   |      | GND      |     |      |
 |  491 |   2 |   PIN.Y7 |   IN | 0 |    |   P/D | 15 || 35 | P/D   |    | 0 | IN   | PIN.Y8   | 15  |  492 |
 |  490 |   3 |   PIN.Y6 |   IN | 1 |    |   P/U | 16 || 36 | P/D   |    | 0 | IN   | PIN.T18  | 16  |  464 |
 |      |     |      GND |      |   |    |       | 17 || 37 | P/D   |    | 0 | IN   | PIN.T19  | 17  |  465 |
 |  413 |   4 |   PIN.D1 | ALT0 | 1 |    |   P/U | 18 || 38 |       |    |   |      | PWR_EN1  |     |      |
 |  414 |   5 |   PIN.D2 | ALT0 | 1 |    | DSBLD | 19 || 39 | P/U   |    | 1 | IN   | PIN.D5   | 18  |  417 |
 |      |     |      3V3 |      |   |    |       | 20 || 40 |       |    |   |      | GND      |     |      |
 +------+-----+----------+------+---+----+-------+----++----+-------+----+---+------+----------+-----+------+