Published April 23, 2026 © CC BY-NC-ND

EInk Shield for Nucode - NU54DK

Design of custom 0.96" Eink display shield board for NU54 Development Kit

BeginnerShowcase (no instructions)8 hours43

Things used in this project

Hardware components

Nordic Semiconductor NUCODE - NU54 DK

ePaper / eInk Eink Shield

Software apps and online services

Microsoft VS Code

Story

Building a Custom E-ink Shield for the NU54-DK Bluetooth EVK

In the world of IoT, power efficiency is king. When I started working with the Nucode NU54-DK Bluetooth Evaluation Kit, I wanted to find a display solution that matched its low-power capabilities. The answer was clear: E-ink.

Today, I’m sharing the process of designing and building a custom 0.96" E-ink Shield specifically tailored for the Nucode ecosystem.

Why the NU54-DK and E-ink?

The NU54-DK is a powerful Bluetooth Low Energy (BLE) development platform. It’s designed for high performance with minimal energy consumption. However, traditional LCD or OLED screens are "power hungry" because they require constant energy to maintain an image.

By using the Good Display 0.96" E-ink (GDEW0097T11), the device only draws power during a screen refresh. Once the image is set, it stays there indefinitely, even if you disconnect the battery.

The Hardware Design

The core of this project was designing a custom PCB (Shield) that bridges the NU54-DK headers with the E-ink display’s specific driving requirements.

The Display: 0.96" E-ink

The display chosen is a 0.96-inch monochrome screen with a resolution of 88x184. It uses an SPI interface, making it compatible with most microcontrollers.

Ultra-wide viewing angle

Ultra-wide viewing angle
Paper-like readability (Perfect for outdoor use)
SPI Interface (CS, MOSI, CLK, RST, D/C, BUSY pins)

The PCB LayoutDesigning the shield required careful routing for the SPI signals and the booster circuit required to drive the E-ink panel. E-ink displays require a specific set of capacitors, Inductors and MOSFETs to handle the high-voltage pulses needed to move the physical ink capsules.

Find more details here https://www.good-display.com/product/486.html

Pin Mapping for NU54-DK

I designed the shield to plug directly into the NU54-DK headers. The mapping ensures that the SPI pins (MOSI, SCK, CS) align perfectly with the Nucode's high-speed peripherals, while the Busy and Reset lines are handled by standard GPIOs.

Design 3D Output

Potential Applications

With this hardware stack (NU54-DK + E-ink Shield), you can build:

Smart Name Tags: Update your name or QR code via Bluetooth.

Sensor Nodes: Display temperature or humidity data that stays visible for weeks on a single coin cell.

Crypto Trackers: A pocket-sized device to track live prices over BLE.

Conclusion

Designing this shield was a great exercise in combining display technology with BLE connectivity. The result is a highly efficient, readable, and versatile development tool for anyone using Nucode’s Bluetooth solutions.

What’s next? I’m currently working on a custom driver library to optimize the refresh rate and introduce "Partial Refresh" to the 0.96" screen!

Schematics

Code

Eink.c

#include <stdint.h>
#include <errno.h>
#include <stdio.h>
#include <string.h>
#include "eink.h"
#include "images.h"
#include <zephyr/drivers/spi.h>
#include <zephyr/drivers/gpio.h>

#define MY_SPI_MASTER DT_NODELABEL(my_spi_master)

static const struct gpio_dt_spec epd_bsy = GPIO_DT_SPEC_GET(DT_ALIAS(gpiobsy), gpios);

static const struct gpio_dt_spec epd_dc = GPIO_DT_SPEC_GET(DT_ALIAS(gpiodc), gpios);

static const struct gpio_dt_spec epd_rst = GPIO_DT_SPEC_GET(DT_ALIAS(gpiorst) , gpios);

static const struct gpio_dt_spec epd_cs = GPIO_DT_SPEC_GET(DT_ALIAS(gpiocs), gpios);

//static const struct gpio_dt_spec epd_en = GPIO_DT_SPEC_GET(DT_ALIAS(gpioeen), gpios);


#define EPD_cs_low() 		gpio_pin_set_dt(&epd_cs, 0);
#define EPD_cs_high() 		gpio_pin_set_dt(&epd_cs, 1);

#define EPD_dc_low() 		gpio_pin_set_dt(&epd_dc, 0);
#define EPD_dc_high() 		gpio_pin_set_dt(&epd_dc, 1);

#define EPD_rst_low() 		gpio_pin_set_dt(&epd_rst, 0);
#define EPD_rst_high() 		gpio_pin_set_dt(&epd_rst, 1);

#define EPD_delay_ms(X)		k_sleep(K_MSEC(X));

extern volatile int lock_status;
extern struct k_sem epd_init_ok;

// SPI master functionality
const struct device *spi_dev;
static struct spi_config spi_cfg = {
	.operation = SPI_WORD_SET(8) | SPI_TRANSFER_MSB, // | SPI_MODE_CPOL | SPI_MODE_CPHA,
	.frequency = 8000000,
	.slave = 0,
	.cs = {.gpio = NULL, .delay = 0},
};



static void spi_sendbyte(uint8_t data)
{

	const struct spi_buf tx_buf = {
		.buf = &data,
		.len = 1
	};
	const struct spi_buf_set tx = {
		.buffers = &tx_buf,
		.count = 1
	};

	int error = spi_write(spi_dev, &spi_cfg, &tx);
	if(error != 0){
		printk("SPI write error: %i\n", error);
	}

}

static void spi_sendbytes(uint8_t *data, uint32_t len)
{

	struct spi_buf tx_buf = {
		.buf = data,
		.len = len
	};
	struct spi_buf_set tx = {
		.buffers = &tx_buf,
		.count = 1
	};

	int error = spi_write(spi_dev, &spi_cfg, &tx);
	if(error != 0){
		printk("SPI write error: %i\n", error);
	}
}

static void sendCmd( uint8_t cmd) {

  EPD_cs_low();
  EPD_dc_low();
  spi_sendbyte(cmd);
  EPD_cs_high();

}

static void sendData( uint8_t data) {

  EPD_cs_low();
  EPD_dc_high();
  spi_sendbyte(data);
  EPD_cs_high();

}

static void sendDatabytes(uint8_t *data, uint32_t len) {

  EPD_cs_low();
  EPD_dc_high();
  spi_sendbytes(data,len);
  EPD_cs_high();

}

void eink_spi_init(void)
{
	spi_dev = DEVICE_DT_GET(MY_SPI_MASTER);
	if(!device_is_ready(spi_dev)) {
		printk("SPI master device not ready!\n");
	}
	printk("spi init done!\r\n");
}

void epd_wait(void)
{
	printk("epd wait start.. status=%d \r\n", gpio_pin_get_dt(&epd_bsy));
    while(gpio_pin_get_dt(&epd_bsy) != 0)
    {
		/* Spin for ever */
		EPD_delay_ms(1);
    }
	printk("epd wait over. status=%d \r\n", gpio_pin_get_dt(&epd_bsy));
}

void epd_gd_soft_reset(void)
{
	sendCmd(0x12);   //Soft-reset
}

void epd_gd_sleep(void)
{
	sendCmd(0x10);
	sendData(0x01);    //Sleep
}

void epd_gd_set_temp()
{
	sendCmd(0x18);
	sendData(0x80);    //temp

	sendCmd(0x22);
	sendData(0xb1);    //temp
	sendCmd(0x20);

	epd_wait();

	sendCmd(0x1a);
	sendData(0x64); 
	sendData(0x00); 

	sendCmd(0x22);
	sendData(0x91); 
	sendCmd(0x20);

	epd_wait();
    printk("epd set temp done\r\n");
}


void epd_gd_set_doc()
{

	sendCmd(0x01); //Driver output control     
	sendData((EPD_GD_HEIGHT+EPD_GD_OFFSET-1)%256); 
	sendData((EPD_GD_HEIGHT+EPD_GD_OFFSET-1)/256); 
	sendData(EPD_GD_MIRROR); // 0x01 - mirror

	sendCmd(0x11);
	sendData(0x01);  //data entry mode 

    printk("epd set doc done\r\n");
}

void epd_gd_set_duc()
{
	uint8_t temp[2] = {0x00, 0x80};

	sendCmd(0x21);
	sendData(0x00); 
	sendData(0x80); //Display update control 

    printk("epd set duc done\r\n");
}

void epd_gd_set_pos()
{
	sendCmd(0x44);
	sendData(0x00); 
	sendData((EPD_GD_WIDTH/8)-1); //Set ram x start/end pos    

	sendCmd(0x45);
	sendData((EPD_GD_HEIGHT+EPD_GD_OFFSET-1)%256); 
	sendData((EPD_GD_HEIGHT+EPD_GD_OFFSET-1)/256); //Set ram y start/end pos    
	sendData(0x00); 
	sendData(0x00); 

	sendCmd(0x3c);
	sendData(0x05); //BorderWaveform
	//sendData(0x80); //Set borderwave

    printk("epd set pos done\r\n");
}

void epd_gd_set_pos2()
{
	sendCmd(0x4E);
	sendData(0x00); //Set ram x count to 0   

	sendCmd(0x4F);
	sendData((EPD_GD_HEIGHT+EPD_GD_OFFSET -1)%256); //Set ram x count to 128   
	sendData((EPD_GD_HEIGHT+EPD_GD_OFFSET -1)/256); 

    printk("epd set pos2 done\r\n");
}


//Full screen refresh display function
void eink_gd_init_bw_0_97(void)
{

	sendCmd(0x24);

	sendDatabytes(gImage_gd_elock_bw_flash_0_97,EPD_GD_BYTES_SIZE);
	sendCmd(0x18);
	sendData(0xff);

	sendCmd(0x22);
	sendData(0xf7);	//Display Update Control
	sendCmd(0x20);//Activate Display Update Sequence

	epd_wait();
}

//Full screen refresh display function
void eink_gd_update_bw_0_97(void)
{

	sendCmd(0x24);

	if(button_status)
	{
		sendDatabytes(gImage_gd_bw_0_97_emclub_logo,EPD_GD_BYTES_SIZE);
	}
	else
	{
		sendDatabytes(gImage_gd_bw_0_97_nucode_logo,EPD_GD_BYTES_SIZE);
		
	}

	sendCmd(0x18);
	sendData(0xff);
	sendCmd(0x22);
	sendData(0xf7);	//Display Update Control
	sendCmd(0x20);	//Activate Display Update Sequence

	epd_wait();
}


void eink_gd_set_white(void)
{

	sendCmd(0x24);
	sendDatabytes(gImage_gd_white_2_13,EPD_GD_BYTES_SIZE);

	sendCmd(0x22);
	sendData(0xf7);	//Display Update Control
	sendCmd(0x20);	//Activate Display Update Sequence

	epd_wait();
}


void eink_gd_hwinit_screen(void)
{
	EPD_rst_low();
	EPD_delay_ms(10);
	EPD_rst_high();
	EPD_delay_ms(10);

	epd_wait();

	epd_gd_soft_reset();  //soft reset

	epd_wait();

	epd_gd_set_doc();

	epd_gd_set_pos();

	epd_gd_set_duc();

	epd_gd_read_temp();

	epd_gd_set_pos2();

	epd_wait();

	printk("EPD init done\r\n");

}



uint8_t eink_configure_gpio(void)
{

	if (!gpio_is_ready_dt(&epd_cs)) {
		return 0;
	}

	if (gpio_pin_configure_dt(&epd_cs, GPIO_OUTPUT) != 0) {
		printk("Failed to configure LED device %s pin %d\n",
				epd_cs.port->name, epd_cs.pin);
	return 0;
	}	

	if (!gpio_is_ready_dt(&epd_dc)) {
		return 0;
	}

	if (gpio_pin_configure_dt(&epd_dc, GPIO_OUTPUT) != 0) {
		printk("Failed to configure LED device %s pin %d\n",
				epd_dc.port->name, epd_dc.pin);
	return 0;
	}

	if (!gpio_is_ready_dt(&epd_rst)) {
		return 0;
	}

	if (gpio_pin_configure_dt(&epd_rst, GPIO_OUTPUT) != 0) {
		printk("Failed to configure LED device %s pin %d\n",
				epd_rst.port->name, epd_rst.pin);
	return 0;
	}

	if (!gpio_is_ready_dt(&epd_bsy)) {
		return 0;
	}

	if (gpio_pin_configure_dt(&epd_bsy, GPIO_INPUT) != 0) {
		printk("Failed to configure %s pin %d\n",
		       epd_bsy.port->name, epd_bsy.pin);
		return 0;
	}


}


void eink_power_off(void)
{
	//gpio_pin_set_dt(&epd_en, 0);
#if 0
	if (gpio_pin_configure_dt(&epd_en, GPIO_DISCONNECTED ) != 0) {
		printk("Failed to configure %s pin %d\n",
		       epd_en.port->name, epd_en.pin);
		return 0;
	}
#endif
	if (gpio_pin_configure_dt(&epd_bsy, GPIO_DISCONNECTED ) != 0) {
		printk("Failed to configure %s pin %d\n",
		       epd_bsy.port->name, epd_bsy.pin);
		return 0;
	}

	if (gpio_pin_configure_dt(&epd_rst, GPIO_DISCONNECTED ) != 0) {
		printk("Failed to configure %s pin %d\n",
		       epd_rst.port->name, epd_rst.pin);
		return 0;
	}

	if (gpio_pin_configure_dt(&epd_cs, GPIO_DISCONNECTED ) != 0) {
		printk("Failed to configure %s pin %d\n",
		       epd_cs.port->name, epd_cs.pin);
		return 0;
	}
	
	if (gpio_pin_configure_dt(&epd_dc, GPIO_DISCONNECTED ) != 0) {
		printk("Failed to configure %s pin %d\n",
		       epd_dc.port->name, epd_dc.pin);
		return 0;
	}


}

Credits

Ashok R

38 projects • 104 followers

Hobbyist/Engineer/Director/Animatior

EInk Shield for Nucode - NU54DK

Things used in this project

Hardware components

Software apps and online services

Story

Why the NU54-DK and E-ink?

The Hardware Design

Potential Applications

Conclusion

Custom parts and enclosures

NU54- EInk Shield 3D design

Schematics

NU54 Eink Shield Schematic

Code

Eink.c

Credits

Ashok R

Comments

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EInk Shield for Nucode - NU54DK

EInk Shield for Nucode - NU54DK

Things used in this project

Hardware components

Software apps and online services

Story

Why the NU54-DK and E-ink?

The Hardware Design

Potential Applications

Conclusion

Custom parts and enclosures

NU54- EInk Shield 3D design

Schematics

NU54 Eink Shield Schematic

Code

Eink.c

Credits

Ashok R

Comments

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