The Dragonwing IQ8-EVK contains one low-speed connector (JLS1) that provides access to various GPIOs, CAN, QUPs, and other interfaces.
Pinout
The figure below shows the default functions of the IQ-8275 EVK 40-pin LS connector.
GPIOs
The following commands require root privileges. Use sudo su to switch to the root user.
Identify GPIO Subsystem Numbers
Identify the base GPIO number by running the following command and looking for platform/f000000.pinctrl (gpiochip4). For IQ-8275, the base is 560.
cat /sys/kernel/debug/gpio
Control GPIOs via sysfs
Export the GPIO
cd /sys/class/gpio
echo 614 > export
Configure direction and value
cd gpio614
echo out > direction
echo 1 > value
| Attribute | Values |
|---|
direction | in (input), out (output) |
value | 0 (low), 1 (high) |
edge | rising, falling, both, none |
Unexport when done
cd ..
echo 614 > unexport
GPIO Code Examples
Sets pin 5 as output, pin 7 as input, and loops to check the level of pin 7.Connect pins and run
Short pin 5 and pin 7 with a Dupont wire.Pay attention to pin order. Do not short power and ground pins — this may damage the board.
Install python3-periphery:apt install python3-periphery
Connect pins and run
Short pin 5 and pin 7 with a Dupont wire.Pay attention to pin order. Do not short power and ground pins — this may damage the board.
UART
Pins 5 and 7 are configured for UART by default (GPIO lines 54 and 55, mapping to uart12 = qup1_se5 (0xa98000)).
Follow the Modify serial engine node procedure to enable the UART interface. After enabling, the device node appears at /dev/ttyHS3.
Connect pins
Short pin 5 and pin 7 with a Dupont wire.
Do not short power and ground pins.
Configure UART
sudo stty -F /dev/ttyHS3 ispeed 115200 ospeed 115200
sudo stty -F /dev/ttyHS3 115200 -echo -icanon -isig -iexten -icrnl -ixon -opost
Open two SSH terminals
Terminal 1 (RX): sudo cat /dev/ttyHS3Terminal 2 (TX): echo "hello world!" > /dev/ttyHS3
I2C
Pins 8 and 10 are configured for I2C by default (GPIO lines 32 and 33, mapping to i2c4 = qup0_se4 (0x990000)).
Follow the Modify serial engine node procedure to enable the I2C interface.
ls /dev/i2c*
sudo apt install -y i2c-tools
i2cdetect -l
i2cdetect -a -y -r 20
SPI
Pins 11 and 13 are configured for SPI by default (GPIO lines 44 and 45, mapping to spi10 = qup1_se3 (0xa8c000)).
Follow the Modify serial engine node procedure to enable the SPI interface.
sudo apt install python3-spidev
