Digital outputs

Pigeon computer RB700 has 8 open drain digital outputs. Fig. 1 shows recommended connection of LED (a) and relays (b,c) to open drain outputs. The internal diodes protect the output transistors from transient voltage peaks (b). In the case of long cables to relay, connection with an external diode (c) is recommended.

Fig. 1. Example digital outputs connections

Table 1. Digital outputs parameters

Parameter	Value
Quantity of outputs	8
Maximum current	500 mA
Maximum voltage	28 V DC

Linux kernel GPIO user space interface

gpiod

Installation of the gpiod tools:

apt install gpiod 

Change state of output O1:

gpioset gpiochip2 0=1
gpioset gpiochip2 0=0

Change state of output O8:

gpioset gpiochip2 7=1
gpioset gpiochip2 7=0

Table 2. Digital outputs - gpiod

Signal	gpiod
O1	gpiochip2 0
O2	gpiochip2 1
O3	gpiochip2 2
O4	gpiochip2 3
O5	gpiochip2 4
O6	gpiochip2 5
O7	gpiochip2 6
O8	gpiochip2 7

GPIO Sysfs Interface for Userspace

Sysfs ABI is deprecated. This old sysfs ABI will not be developed (no new features), it will just be maintained.

Change state of output O1:

echo "488" > /sys/class/gpio/export
echo "out" > /sys/class/gpio/gpio488/direction
echo "1" > /sys/class/gpio/gpio488/value
echo "0" > /sys/class/gpio/gpio488/value
echo "488" > /sys/class/gpio/unexport

Table 3. Digital outputs - Sysfs

Signal	GPIO Sysfs
O1	GPIO488
O2	GPIO489
O3	GPIO490
O4	GPIO491
O5	GPIO492
O6	GPIO493
O7	GPIO494
O8	GPIO495

 

Links

• kernel.org - libgpiod
• kernel.org - GPIO Sysfs Interface for Userspace