NRF 52 OLED SSD 1306 SEGGER

Question

Hello to all

I am quite lost, I need help to connect an oled to my project. The rest of the stages I have it complete, but my experience with OLED, is limited to arduino with U8G2 type libraries, that is, I don't know how to connect and configure my display with my board.

I am using NRF52DK and segger Studio.

Any recommendations on how I should start, or example with my environment?

Thank you very much

helsing · Accepted Answer

Hi Daniel,

I was able to reproduce the issue you are facing, as well as finding a solution.

Things should work if you use the twi driver instead of twim, and in addition remove zephyr,concat-buf-size = <4096>; from the overlay.

The reason is that twim is using DMA but nRF52832 is only able to send a limited amount of bytes. For example nRF52840, nRF5340 and nRF9160 are not affected by this limitation when it comes to writing to these displays. twi is able to output data continuously, although the CPU becomes a bit more occupied as DMA is not used.

Here is the full overlay:

/ {
	chosen {
		zephyr,display = &ssd1306;
	};
};

&pinctrl {
    i2c0_default: i2c0_default {
        group1 {
            psels = <NRF_PSEL(TWIM_SDA, 0, 26)>, 
                <NRF_PSEL(TWIM_SCL, 0, 27)>;     
        };
    };

    i2c0_sleep: i2c0_sleep {
        group1 {
            psels = <NRF_PSEL(TWIM_SDA, 0, 26)>, 
                <NRF_PSEL(TWIM_SCL, 0, 27)>;     
            low-power-enable;
        };
    };
};

arduino_i2c: &i2c0 {
	compatible = "nordic,nrf-twi";
	status = "okay";
	clock-frequency = <I2C_BITRATE_FAST>;
    
  
	ssd1306: ssd1306@3c {
		compatible = "solomon,ssd1306fb";
		reg = <0x3c>;
		width = <128>;
		height = <64>;
		segment-offset = <0>;
		page-offset = <0>;
		display-offset = <0>;
		multiplex-ratio = <63>;
		segment-remap;
		com-invdir;
		prechargep = <0x22>;
	};
};

Attached is the working project I tested, using nRF Connect SDK v2.1.2.

lvgl-20230110.zip

If you are using nRF Connect SDK v2.2.0 or later you might need to update the overlay with the below code, due to the new naming format. This section of code becomes included when using the shield, so it is not really necessary to include it in the overlay, and could be removed.

/ {
	chosen {
		zephyr,display = &ssd1306_ssd1306_128x64;
	};
};