ESP8266 Builtin OLED – Heltec WiFi Kit 8

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A  set-up guide for the Heltec WiFi Kit 8 development board (an ESP8266 with built-in OLED display).

Follow the easy steps below to get up and running with this board using standard Arduino libraries.

This board is based on the ESP8266 chip and has onboard WiFi,  a 0.96inch 128*32 OLED display, lithium battery connector charging and a CP2014 USB to serial interface. It also works with the Arduino IDE! I bought mine from here: https://aliexpress.com/item/ESP8266-WIFI-Chip-0-91-inch-OLED-CP2014-32Mb-Flash-ESP-8266-Module-Internet-of-things/32822165059.html but it’s also available on eBay and Amazon.

Setting Up the Arduino IDE for the ESP8266 Range

The ESP8266 boards are much easier to set up in the Arduino IDE than the ESP32 range. If you don’t already have it installed, download and install the IDE from here: https://www.arduino.cc/en/main/software (don’t use the Web version).

In the IDE, open the File Menu and choose Preferences and enter http://arduino.esp8266.com/stable/package_esp8266com_index.json into the Additional Board Manager URLs field.

Add ESP 8266 Library

Open the Boards Manager from Tools > Board:xxxxx menu

Board Manager

Find esp8266 by ESP8266 Community in the list and click Install

Hardware Library

The ESP8266 Hardware Libraries are now installed and you can test your new board with a simple Sketch.

Testing the WiFi is Functioning

In the Arduino IDE, in the Tools > Board menu choose NodeMCU 1.0 (ESP-12E Module)

Select Nodemcu

Select the port (It might not be COM4)

Select Port

You can now upload Sketches to the board. A good test is use the example WiFiScan sketch.

Open File> Examples > ESP8266WiFi > WifiScan and upload the sketch.

If you open the Serial Monitor (Tools > Serial Monitor) you will be able to see any WiFi access points in range. Check the baud rate is the same as in the sketch – probably 115200.

WiFi Scan Example

 

Displaying data on the WiFi Kit 8 OLED

You should be able to use any SSD1306 library for the OLED. I prefer the U8g2 (https://github.com/olikraus/u8g2) library. It can be installed using the Arduino IDE library manager. Open Sketch > Include Library > Manage Libraries and search for and then install U8g2.

U8g2 has three different display methods. To test the board we are using the Full Buffer method. Open the example Sketch:  File> Examples > U8g2 > full_buffer > GraphicsTest

In the code for this Sketch, paste:
U8G2_SSD1306_128X32_UNIVISION_F_SW_I2C u8g2(U8G2_R0, /* clock=*/ 5, /* data=*/ 4, /* reset=*/ 16);
Above this line: // Please UNCOMMENT one of the contructor lines below
Upload the sketch. You should see some different graphics appearing on the screen. Don’t worry that they are cut off, this example sketch is designed for different size screens.

If this doesn’t work you might have a different version of the board. Try pasting the following:
U8G2_SSD1306_128X32_UNIVISION_F_SW_I2C u8g2(U8G2_R0, /* clock=*/ 14, /* data=*/2 /* reset=*/ 4);

Displaying a Scrolling Message on the OLED

Displaying a scrolling message can be a little tricky due to hardware and font limitations. The following sketch (based on the U8g2 ScrollingText example) will horizontally scroll a short piece of text.

#include <U8g2lib.h>

//U8g2 Contructor
U8G2_SSD1306_128X32_UNIVISION_F_SW_I2C u8g2(U8G2_R0, /* clock=*/ 5, /* data=*/ 4, /* reset=*/ 16);
// Alternative board version. Uncomment if above doesn't work.
// U8G2_SSD1306_128X32_UNIVISION_F_SW_I2C u8g2(U8G2_R0, /* clock=*/ 14, /* data=*/ 2, /* reset=*/ 4);

u8g2_uint_t offset;     // current offset for the scrolling text
u8g2_uint_t width;      // pixel width of the scrolling text (must be lesser than 128 unless U8G2_16BIT is defined
const char *text = "ROB01 "; // scroll this text from right to left


void setup(void) {
  u8g2.begin();

  u8g2.setFont(u8g2_font_logisoso32_tf); // set the target font to calculate the pixel width
  width = u8g2.getUTF8Width(text);    // calculate the pixel width of the text

  u8g2.setFontMode(0);    // enable transparent mode, which is faster
}


void loop(void) {
  u8g2_uint_t x;

  u8g2.firstPage();
  do {

    // draw the scrolling text at current offset
    x = offset;
    u8g2.setFont(u8g2_font_logisoso32_tf);   // set the target font
    do {                // repeated drawing of the scrolling text...
      u8g2.drawUTF8(x, 32, text);     // draw the scolling text
      x += width;           // add the pixel width of the scrolling text
    } while ( x < u8g2.getDisplayWidth() );   // draw again until the complete display is filled

    u8g2.setFont(u8g2_font_logisoso32_tf);   // draw the current pixel width
    u8g2.setCursor(0, 64);
    u8g2.print(width);          // this value must be lesser than 128 unless U8G2_16BIT is set

  } while ( u8g2.nextPage() );

  offset -= 1;            // scroll by one pixel
  if ( (u8g2_uint_t)offset < (u8g2_uint_t) - width )
    offset = 0;             // start over again
}


If you want to scroll a longer piece of text you have to edit one of the display library files to allow 16bit mode.

Open the file /libraries/U8g2_Arduino/src/clib/u8g2.h and uncomment this line:
// #define U8G2_16BIT

Save the file and you can now use longer text by replacing this line:
const char *text = “ROB01 “; // scroll this text from right to left
with (for example):
const char *text = “ROBOTZERO.ONE “; // scroll this text from right to left

You’ll then see something like the animation below:

Bonus tip! You can make the animation smoother by boosting the CPU speed to 160Mhz for the uploaded Sketch:

CPU Frequency

Further Information

More detailed information about pins and the two board versions: http://stefanfrings.de/esp8266/#wifikit8
Reference for the display library, including custom fonts etc: https://github.com/olikraus/u8g2/wiki/u8g2reference
ESP32 version setup: https://robotzero.one/heltec-wifi-kit-32/
Heltec on Github: https://github.com/Heltec-Aaron-Lee/WiFi_Kit_series

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6 Replies to “ESP8266 Builtin OLED – Heltec WiFi Kit 8”

  1. William MOORE says:

    Love this guide thanks! but I’m stuck at no port selectable. I’ve picked out the exact board stated, and port remains dimmed sadly! No reaction from windows 10 when plugged in yet the board happily displays a hello world sketch from factory.. I notice in the manual for this which is in Chinese lol.. the board is selected as wifi_kit_32 ?? With a dead link to I presume a zip file of drivers :/ (installed cp210 and rebooted before all this btw – doesn’t show in DM at all)

    1. WordBot says:

      Is it the Kit 8 or the 32 you have?

      Kit 8 looks like this in my Device Manager…

      https://robotzero.one/wp-content/uploads/2018/01/heltec-port.jpg

      Can you see anything with question marks in Device Manager?

      1. William MOORE says:

        Kit 8 printed on board.
        Problem was my side. I got so fed up I backed all my stuff up to the NAS and reset the entire PC! lol
        -Installed the CP210 drivers again from another page – that I didn’t know I needed in win10 reading this guide,
        and hey presto. Though I might add I get a menu of examples just for this Node. (you suggest using examples/wifi/wifi scan -not there for me.)

        Got it going through the examples/examples for nodeMCU 1 etc/esp8266wifi/wifiscan
        and your graphics example. This was no plain sail but thanks for some pointers.
        The simplest of sketches takes up to 2-3 mins to compile and upload, that surprised me I thought it would be quicker.

        1. WordBot says:

          Where did you get the CP210 drivers? I had to install this https://www.silabs.com/products/development-tools/software/usb-to-uart-bridge-vcp-drivers for the ESP32 version of this board to work. I might need to add that to the instructions. I thought I’d created this on a fresh Win10 install but maybe not.

          I’ve corrected the WiFi Scan menu path in the article to the correct path as you’ve written.

          I think they take a long time as the ESP8266 is much more complicated that the original Arduino boards so the libraries etc are much larger so take a while to compile and upload.

  2. Redbeard says:

    Hi, Thanks for the write up. Do you know what kind of JST cable fits this particular unit? I’m looking to get a Lithium battery for it, but I don’t know what kind to get.

    1. WordBot says:

      Maybe JST 1.25 mm 2 pin? The LiPo connector I have doesn’t fit. Make sure you use batteries with the built in protection circuit as I don’t know how well the charging circuit on this device manages over charging or discharging. Something I need to investigate.

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