This is a simple and extensively commented example on how to use an I2C peripheral connected to a Raspberry Pi 3 running on the balena platform. (Disclaimer: I work for balena.)
The concepts shall be the same regardless of which I2C peripheral you want to use, but here I am using a little 128x64 pixels monochrome OLED display driven by an SSD1306 chip. It's similar to this Monochrome 0.96" 128x64 OLED Graphic Display by Adafruit.
Anyway, go check the code. It's well-documented.
A picture would definitely help here, but for now all I have is this:
| Display Pin | Raspberry PI GPIO Pin Number | Raspberry PI GPIO Pin Description |
|---|---|---|
| VCC | 1 | 3v3 Power |
| GND | 6 | Ground |
| SDA (Data) | 3 | GPIO 2 (I2C1 SDA) |
| SCL (Clock) | 5 | GPIO 2 (I2C1 SCL) |
Actually there's not much margin to be creative when connecting I2C peripherals to a Pi, but you may want to check the Raspberry Pi Pinout website for some more info.
I was able to improve the refresh times of my display by increasing the I2C baud
rate. In a balena world, you simply need to set the config variable
BALENA_HOST_CONFIG_dtparam to i2c_arm=on,i2c_baudrate=1000000.
The magic is really done by i2c_baudrate=1000000, but you also need to add
i2c_arm=on to ensure I2C is enabled. balena will enable I2C by default, but
since we are manually changing the dtparams, we have to explicitly set all the
values that matter for us. (This would be the same for other parameters that
balena sets by default, like audio=on).