Programming Reference

GPIO pin assignments and code examples for programming IRIV PiControl I/O.

GPIO Pin Assignments

Digital Inputs (Terminal 2)

Terminal	GPIO Pin	Logic	Voltage Range
DI0	GPIO13	Active HIGH	3V - 50V
DI1	GPIO17	Active HIGH	3V - 50V
DI2	GPIO22	Active HIGH	3V - 50V
DI3	GPIO27	Active HIGH	3V - 50V

Input type: Wet contact (requires external voltage)

Digital Outputs (Terminal 1)

Terminal	GPIO Pin	Logic	Specifications
DO0	GPIO23	Active HIGH	Up to 50V, 500mA
DO1	GPIO24	Active HIGH	Up to 50V, 500mA
DO2	GPIO25	Active HIGH	Up to 50V, 500mA
DO3	GPIO26	Active HIGH	Up to 50V, 500mA

Output type: Dry contact (solid state relay)

User Controls

Function	GPIO Pin	Description
User Button	GPIO4	Input, active LOW when pressed
LED0	GPIO20	Output, user-programmable LED
LED1	GPIO21	Output, user-programmable LED
Buzzer	GPIO19	Output, beeps when HIGH
Mini PCIe Power	GPIO6	Output, HIGH to enable power to Mini PCIe socket

Analog Input (ADC)

Chip: ADS1115 Interface: I2C address 0x48, bus 1 Channels: 4 (AI0, AI1, AI2, AI3)

Python Library Installation

pip install Adafruit_ADS1x15

Initialization

import Adafruit_ADS1x15

# Initialize the ADC
adc = Adafruit_ADS1x15.ADS1115(address=0x48, busnum=1)

Reading 0-10V Voltage Input

# Read ADC
# Param 1 = Analog Input Channel (0-3)
# Param 2 = ADC Gain (Gain 1 for 0-10V)
val = adc.read_adc(0, gain=1)

# Calculate the analog voltage (V)
# Full scale value = 32767
# Full scale voltage = 4.096V
# Voltage divider scale = 2.5
# voltage(V) = val / 32767 * 4.096 * 2.5
voltage = val / 3200

Reading 0-5V Voltage Input

# Read ADC
# Param 1 = Analog Input Channel (0-3)
# Param 2 = ADC Gain (Gain 2 for 0-5V)
val = adc.read_adc(0, gain=2)

# Calculate the analog voltage (V)
# Full scale value = 32767
# Full scale voltage = 2.048V
# Voltage divider scale = 2.5
# voltage(V) = val / 32767 * 2.048 * 2.5
voltage = val / 6400

Reading 0-20mA Current Input

Important: DIP switch must be ON to enable the internal shunt resistor.

# Read ADC
# Param 1 = Analog Input Channel (0-3)
# Param 2 = ADC Gain (Gain 2 for 0-20mA)
val = adc.read_adc(0, gain=2)

# Calculate the current (mA)
# Full scale value = 32767
# Full scale voltage = 2.048V
# Voltage divider scale = 2.5
# Shunt resistor value = 250 ohm
# voltage(V) = val / 32767 * 2.048 * 2.5
# current(mA) = voltage * 1000 / 250
current = val / 1600

Serial Communication

RS485

Device: /dev/ttyACM0 Maximum baud rate: 500 kbps Direction control: Automatic

Example using pySerial:

import serial

# Open RS485 port
ser = serial.Serial(
    port='/dev/ttyACM0',
    baudrate=9600,
    timeout=1
)

# Write data
ser.write(b'Hello RS485\n')

# Read data
data = ser.read(100)
print(data)

ser.close()

RS232

Device: /dev/ttyACM1 Maximum baud rate: 120 kbps

Example using pySerial:

import serial

# Open RS232 port
ser = serial.Serial(
    port='/dev/ttyACM1',
    baudrate=9600,
    timeout=1
)

# Write data
ser.write(b'Hello RS232\n')

# Read data
data = ser.read(100)
print(data)

ser.close()

I2C Devices

Access to onboard I2C devices requires I2C to be enabled (via configuration script).

I2C Bus 1 Devices

Device	Address	Purpose
OLED Display (SSD1306)	0x3C	Status display
ADC (ADS1115)	0x48	Analog input
Crypto Auth (ATECC608B)	0x60	Authentication

I2C Bus 0 Devices

Device	Address	Purpose
RTC (PCF85063A)	0x51	Real-time clock

Complete Example: Digital I/O Control

Not specified in current sources: Complete GPIO control example code.

Standard Raspberry Pi GPIO libraries (RPi.GPIO, gpiozero) can be used with the GPIO pin numbers listed above.

Additional Programming Resources

For general Raspberry Pi GPIO programming:

• RPi.GPIO documentation
• gpiozero documentation
• Official Raspberry Pi programming guides

For I2C device programming:

• Adafruit CircuitPython libraries
• smbus2 Python library

For serial communication:

• pySerial documentation

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Source(s):

• IRIV PiControl CM4 User Manual, Rev 1.3, Nov 2025, Sections 3, 4, 5