TS-7180 TWI
The i.MX6 supports standard I²C at 100 kHz, or using fast mode for 400 kHz operation. The CPU is connected to two I²C buses on the TS-7180.
I2C1 is internal to the TS-7180 and connects to the onboard Silabs supervisory microcontroller at 100 kHz; and to the onboard ST M41T00S real-time clock (RTC).
| Address | Device |
|---|---|
| 0x4a | #Silabs |
| 0x68 | #RTC |
The second I²C bus, I2C3, is connected to the onboard FPGA, for communication between it and the CPU. This bus also runs at 400 kHz by default.
| Address | Device |
|---|---|
| 0x28-0x2f | #FPGA |
In addition to the CPU I²C buses, a bit-banged I²C interface is available on the daughter-card interface, using gpio. The following command will instantiate (create a device node for) a new ssd1306 display at I²C address 0x3C:
echo ssd1306 0x3c > /sys/bus/i2c/devices/i2c-4/new_device
Once this is done, i2c-tools can manipulate the I²C device, or a the downstream developer can write their own client. Technologic Systems has provided a simple client program for writing to an SSD1306 OLED display connected to the HD12 connector. The photo below shows output on the display.
Download the source-code tarball here: File:Ssd1306-demo.tar.gz
| Note: | It is also possible to request the kernel to bitbang additional I²C buses as needed. See an example here. |
The kernel makes the I²C available at /dev/i2c-#, where "#" is 0, 2, or 4. You can use the i2c-tools (i2cdetect, i2cget, i2cset), or you can write your own client.