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Display Setup

There are two types of display connections. One uses a four-wire I2C connection. The other is a 7-wire SPI connection. In this example we will use the 7-wire SPI interface.

Creating a Display Cable

One of the first steps is to connect the OLED to the ports of the robot. Here is a photo of the connections on the back of the OLED screen.

On the right you will see the following connections from top to bottom:

Label Description
CS Chip Select (Slave Select) - Selects this device on the SPI bus
--- ---
DC Data/Command - Indicates whether data being sent is a command (LOW) or display data (HIGH)
RES Reset - Active LOW reset pin to initialize the display
SDA Serial Data - SPI data line (MOSI) for sending data to the display
SCLK Serial Clock - SPI clock signal for data synchronization
VDD 3.3 to 5 volt power
VSS Ground

These pins represent the standard SPI interface for OLED displays:

  • CS is pulled LOW to activate communication with this specific device
  • DC switches between command mode (LOW) and data mode (HIGH)
  • RES should be pulled LOW briefly during initialization to reset the display
  • SDA carries the serial data from the microcontroller to the display (also known as MOSI - Master Out Slave In)
  • SCLK carries the clock signal that synchronizes data transmission

We will connect wires to these connections.

Cytron Display Connection

The Cytron uses a four pin Grove connector. This can be used to connect the power, ground, data and clock. We can then use the servo pins for the other three connections.

Cytron ROBO PICO

The Cytron PICO ROBOT has a female header that can be used to directly connect the display cable. You do not need to use any of the Grove connectors to connect the display.

Testing the Display

After you have created your display cable you can test your display with the following code:

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import machine
import ssd1306

SCK=machine.Pin(2)
SDL=machine.Pin(3)
spi=machine.SPI(0,sck=SCK, mosi=SDL)
CS = machine.Pin(15)
DC = machine.Pin(14)
RES = machine.Pin(13)
oled = ssd1306.SSD1306_SPI(128, 64, spi, DC, RES, CS)

oled.fill(0)
oled.text('Hello World!', 0, 0)
oled.show()

Note this is an example of the hardware SPI interface. There is also a software interface that includes the baudrate parameter.

Details on how the SSD1306 is used can be found on the MicroPython Tutorial Docs Site for the ESP. The code will run the same on the RP2.