Orange Pi Zero – I/O

I finally figured out how to do simple I/O on the GPIO pins on the Orange Pi Zero. It’s actually the same as Raspberry Pi and it relies on /sys/class/gpio/

Most important: Use Armbian, and I in particular use 3.4.113 (legacy).

GPIO

 

Linux GPIO	SOC	Label	CON4	CON4	Label	SOC	Linux GPIO
		Vcc3V3-EXT	1	2	DCIN-5V
12	PA12	TWI0-SDA	3	4	DCIN-5V
11	PA11	TWI0-SCK	5	6	GND
6	PA6	PWM1	7	8	UART1_TX	PG6	198
		GND	9	10	UART1_RX	PG7	199
1	PA1	UART2_RX	11	12	PA7	PA7	7
0	PA0	UART2_TX	13	14	GND
3	PA3	UART2_CTS	15	16	TWI1-SDA	PA19	19
		VCC3V3-EXT	17	18	TWI1-SCK	PA18	18
15	PA15	SPI1_MOSI	19	20	GND
16	PA16	SPI1_MISO	21	22	UART2_RTS	PA2	2
14	PA14	SPI1_CLK	23	24	SPI1_CS	PA13	13
		GND	25	26	PA10	PA10?

Note: PA10 does not seem to work.

 

To enable one GPIO pin, do this as root:

echo 7 >/sys/class/gpio/export
chmod a+rw /sys/class/gpio/gpio7/*

Now in NodeJS you can do (as non-root):

var Gpio = require('onoff').Gpio, 
  led = new Gpio(7, 'out'); 
 
function blinkled7() { 
  var state=false; 
  return function () { 
    console.log(state); 
    if (state) led.writeSync(0) 
    else led.writeSync(1); 
    state = ! state; 
    } 
} 
 
f=blinkled7(); 
setInterval(f, 1000);

which blinks GPIO pin 7 (AKA PA7). You can also watch pins:

var Gpio = require('onoff').Gpio,
  led = new Gpio(7, 'out'),
  button = new Gpio(16, 'in', 'both');

button.watch(function (err, value) {
  if (err) {
    throw err;
  }
  console.log("Changing to ", value);
  led.writeSync(value);
});

process.on('SIGINT', function () {
  console.log("Leaving...");
  led.unexport();
  button.unexport();
});

which makes the LED match what PA16 is. If you connect PA16 to e.g. PA6, you can change PA6, which is detected by PA16 which is reflected in the LED change on PA7!

 

LED’s

The 2 on-board LED’s can be controlled via

echo [0|1] > /sys/class/leds/[red|green]_led/brightness

which map to PA17 (red) and PL10 (green), but those are (of course) claimed by the LED driver.

PWM

Not figured out yet.