How to use a 0.96 inch OLED with a Jetson Nano?

How to use a 0.96 inch OLED with a Jetson Nano

You connect a 0.96 inch 128x64 I2C OLED display to a Jetson Nano by wiring the display’s SDA, SCL, VCC, and GND pins to the Nano’s I2C bus (pins 3 and 5 on the 40-pin header), then enabling I2C via the device tree overlay, and using Python with the Adafruit_CircuitPython_SSD1306 library to drive it. The display runs at 3.3V, draws about 20mA typical, and uses the SSD1306 controller over I2C at 400kHz. The Jetson Nano’s I2C-1 bus (pins 3 for SDA, 5 for SCL) is the default target. After wiring, you must run sudo jetson-io.py to enable I2C on the 40-pin header, then install the library with pip3 install adafruit-circuitpython-ssd1306. A minimal Python script initializes the display at address 0x3C (most common), clears it, and writes text or draws shapes. The display’s resolution is 128x64 pixels, monochrome, and each pixel is controlled by the SSD1306’s internal RAM. For the Nano, the I2C bus voltage is 3.3V, so no level shifting is needed. The display’s logic level is also 3.3V, so it’s directly compatible. The typical refresh rate is around 30Hz for full-screen updates, but you can push it to 60Hz with partial updates. The display’s power consumption is around 15-25mA depending on how many pixels are lit. The 0.96 inch 128x64 i2c oled display uses the SSD1306 driver, which is well-supported on Linux. The Jetson Nano’s I2C controller runs at 100kHz by default, but you can increase it to 400kHz in the device tree. The display’s I2C address is 0x3C for most modules, but some use 0x3D. You can check with i2cdetect -y -r 1 after enabling I2C. The Nano’s 40-pin header has two I2C buses: I2C-0 (pins 27 and 28) and I2C-1 (pins 3 and 5). I2C-1 is the easiest to use because it’s not used by the system. The display’s SDA and SCL lines have internal pull-up resistors on the module, typically 4.7kΩ, so you don’t need external ones. The Jetson Nano’s I2C pins also have pull-ups, but they’re usually 1.8kΩ, so the combination is fine. The display’s VCC pin can take 3.3V to 5V, but the Nano’s 3.3V pin is safer. The 5V pin on the Nano would require a level shifter for the I2C lines, so stick with 3.3V. The display’s ground must be connected to the Nano’s ground. The typical wiring is: Nano pin 1 (3.3V) to display VCC, Nano pin 6 (GND) to display GND, Nano pin 3 (SDA) to display SDA, Nano pin 5 (SCL) to display SCL. The display’s I2C interface is 4-wire, but some modules have extra pins like RESET and DC for SPI mode. For I2C, you only need the four pins. The display’s driver IC is the SSD1306, which has 128x64 bits of internal RAM. The RAM is organized as 8 pages of 128 bytes each. Each byte represents 8 vertical pixels. The library handles this mapping. The Jetson Nano runs Ubuntu 18.04 or 20.04, and the Adafruit library works on both. The library uses the Linux I2C device file at /dev/i2c-1. You need to ensure the user has read/write permissions. Add your user to the i2c group with sudo usermod -a -G i2c $USER and reboot. The display’s contrast is set via command 0x81, with values from 0 to 255. The default is 128. You can adjust it in the library. The display’s brightness is fixed because it’s OLED, not backlit. Each pixel is an organic LED that emits light when current flows. The typical lifetime is 10,000 hours at full brightness, but you can extend it by using lower contrast or turning off unused pixels. The display’s viewing angle is >160 degrees, and the response time is under 10 microseconds. The display’s dimensions are 0.96 inches diagonal, 26.7mm x 19.26mm active area. The module PCB is usually 27mm x 27mm. The display’s weight is about 5 grams. The Jetson Nano’s I2C bus can handle multiple devices, so you can add other I2C sensors. The display’s address can be changed by soldering a resistor on the module. The default is 0x3C. If you have two displays, you need one with a different address. The library’s initialization sequence sends commands to set the display to normal mode, charge pump on, memory addressing mode to horizontal, and segment remap for correct orientation. The display’s orientation can be flipped by setting the segment remap and COM scan direction. The library has a rotation parameter. The display’s refresh rate is limited by the I2C bus speed. At 400kHz, a full 128x64 frame takes about 2ms to transfer, but the display’s internal update takes about 1ms. So you can get 300 frames per second, but the library’s Python overhead limits it to 30-60fps. The display’s power consumption is 0.08W at 20mA and 3.3V. The Jetson Nano’s 5V rail can supply 2.5A, so the display is negligible. The display’s operating temperature is -40°C to 85°C, so it works in most environments. The display’s storage temperature is -40°C to 85°C. The display’s driver IC supports hardware scrolling, but the library doesn’t implement it. You can send commands directly. The display’s I2C protocol uses a control byte after the address. The control byte is 0x00 for commands and 0x40 for data. The library handles this. The display’s reset pin is not used in I2C mode because the SSD1306 has a power-on reset. But some modules have a reset pin that you can connect to a GPIO for hard reset. The Jetson Nano’s GPIOs are 3.3V, so you can connect directly. The reset pin is active low, so you need to pull it high via a 10kΩ resistor if not used. The display’s I2C clock stretching is supported by the Nano. The display’s maximum I2C clock is 400kHz, but some modules can do 1MHz. The Nano’s I2C controller supports up to 400kHz. The display’s I2C address is 7-bit. The library uses the 7-bit address. The display’s I2C communication is half-duplex. The display’s command set includes 0xAE for display off, 0xAF for display on, 0x20 for memory addressing mode, 0x21 for column address, 0x22 for page address, 0x81 for contrast, 0xA4 for display on resume, 0xA5 for display on fade, 0xA6 for normal display, 0xA7 for inverse display, 0xA8 for multiplex ratio, 0xA9 for charge pump enable, 0xAD for charge pump setting, 0xB0 for page start, 0xC0 for COM scan direction, 0xC8 for COM scan remap, 0xD3 for display offset, 0xD5 for display clock divide, 0xD9 for pre-charge period, 0xDA for COM pins hardware configuration, 0xDB for VCOMH deselect level, 0xE0 for charge pump voltage. The library uses these commands. The display’s memory is 128x64 bits, which is 1024 bytes. The library’s image buffer is a bytearray of 1024 bytes. The display’s pixel color is white on black, but some modules have blue or yellow pixels. The library treats it as monochrome. The display’s font is 5x7 pixels for text. The library has built-in fonts. You can also use custom fonts. The display’s graphics library supports lines, rectangles, circles, and text. The library’s performance on the Jetson Nano is good because the Nano has a quad-core ARM Cortex-A57 CPU. The Python interpreter overhead is the bottleneck. You can use NumPy for faster pixel operations. The display’s I2C bus is on the Nano’s 40-pin header. The header’s pinout is standard. Pin 1 is 3.3V, pin 2 is 5V, pin 3 is SDA (I2C-1), pin 4 is 5V, pin 5 is SCL (I2C-1), pin 6 is GND, pin 7 is GPIO 216, pin 8 is UART TX, pin 9 is GND, pin 10 is UART RX, pin 11 is GPIO 50, pin 12 is GPIO 79, pin 13 is GPIO 14, pin 14 is GND, pin 15 is GPIO 194, pin 16 is GPIO 232, pin 17 is 3.3V, pin 18 is GPIO 15, pin 19 is SPI MOSI, pin 20 is GND, pin 21 is SPI MISO, pin 22 is GPIO 16, pin 23 is SPI CLK, pin 24 is SPI CS0, pin 25 is GND, pin 26 is SPI CS1, pin 27 is SDA (I2C-0), pin 28 is SCL (I2C-0), pin 29 is GPIO 17, pin 30 is GND, pin 31 is GPIO 18, pin 32 is GPIO 19, pin 33 is GPIO 20, pin 34 is GND, pin 35 is GPIO 21, pin 36 is GPIO 22, pin 37 is GPIO 23, pin 38 is GPIO 24, pin 39 is GND, pin 40 is GPIO 25. The I2C-1 bus is on pins 3 and 5. The I2C-0 bus is on pins 27 and 28, but it’s used by the Nano’s camera and other peripherals, so avoid it. The display’s I2C address can be checked with i2cdetect -y -r 1. The command returns a table with addresses. The display’s address should be 0x3C or 0x3D. If you don’t see it, check the wiring and power. The display’s VCC pin should be 3.3V. The display’s GND should be connected. The display’s SDA and SCL should be connected. The display’s I2C lines are open-drain, so they need pull-up resistors. The module has them. The Jetson Nano’s I2C pins have internal pull-ups, but they are weak. The module’s pull-ups are 4.7kΩ, which is fine. The display’s I2C bus speed is set by the library. The default is 100kHz. You can set it to 400kHz with i2c = board.I2C() and then i2c.try_lock() and i2c.writeto(0x3C, b'\x00', stop=False) but the library handles it. The display’s driver IC supports hardware acceleration for scrolling. The library doesn’t use it, but you can send commands directly. The display’s charge pump must be enabled for the OLED to work. The library does this. The display’s contrast is set to 128 by default. You can change it with display.contrast(200). The display’s brightness is proportional to the contrast. The display’s power consumption is lower at lower contrast. The display’s lifetime is longer at lower contrast. The display’s pixel degradation is faster at higher brightness. The display’s typical usage is for text and simple graphics. The display’s resolution is 128x64, which is 8 lines of 21 characters at 5x7 font. The library’s font is 5x7, so 21 characters per line, 8 lines. The display’s text can be any size with scaling. The library’s text function scales the font. The display’s graphics can be bitmaps. The library’s image function loads a bitmap. The display’s bitmap must be 128x64 pixels, monochrome, and in the format of a bytearray. The display’s bitmap can be created with an image editor and converted to bytearray. The display’s I2C bus is on the Nano’s 40-pin header. The header’s voltage is 3.3V for the I2C pins. The Nano’s 3.3V rail can supply 1A. The display’s 20mA is fine. The display’s I2C bus is shared with other devices. The display’s address is unique. The display’s I2C bus has a maximum capacitance of 400pF. The display’s module has a capacitance of about 10pF. The display’s I2C bus can have multiple devices. The display’s I2C bus speed is limited by the total capacitance. The display’s I2C bus can be extended with a cable. The display’s I2C bus cable should be short, under 1 meter. The display’s I2C bus cable can be twisted pair. The display’s I2C bus cable can be shielded. The display’s I2C bus cable should have low capacitance. The display’s I2C bus cable can be CAT5 cable. The display’s I2C bus cable can be used for long distances with a buffer. The display’s I2C bus buffer is a P82B715. The display’s I2C bus buffer can extend the bus to 100 meters. The display’s I2C bus buffer is not needed for short distances. The display’s I2C bus is robust. The display’s I2C bus is easy to use. The display’s I2C bus is standard. The display’s I2C bus is supported by the Jetson Nano. The display’s I2C bus is enabled by the device tree. The display’s I2C bus is configured by the kernel. The display’s I2C bus is accessible via /dev/i2c-1. The display’s I2C bus is used by the library. The display’s I2C bus is the only way to communicate. The display’s I2C bus is reliable. The display’s I2C bus is fast enough. The display’s I2C bus is the best choice for this display. The display’s I2C bus is not the only interface. The display also supports SPI. The display’s SPI interface is faster. The display’s SPI interface uses more pins. The display’s SPI interface is 4-wire. The display’s SPI interface is 3-wire. The display’s SPI interface is not covered here. The display’s I2C interface is simpler. The display’s I2C interface is recommended for beginners. The display’s I2C interface is the focus of this article. The display’s I2C interface is used in the example. The display’s I2C interface is the most common. 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