Description

This ADC breakout board is specially designed for pcDuino8 Uno which has no on-board ADC module. It expands 6 ADC channels using ADI AD7997 12-bit ADC module which provides a I2C-compatible interface.

Feature

• ADI AD7997 12-bit ADC chip
• 10- and 12-bit ADC
• 8 single-ended analog input channels (Only use 6 channels)
• I2C-compatible serial interface
• 3.3V power supply

Tutorial

Connect to pcDuino8 Uno

• Solder 90° 10-pins headers on J10 of pcDuino8 Uno
• Plug the ADC breakout board into J10 (as shown in the following picture).

Quick test

• Install additional package(s) before use pcduino8_uno_lib on pcDuino8 Uno

  sudo apt-get install libi2c-dev i2c-tools

• Fetch the Arduino lib for pcDuino8 Uno

  git clone https://github.com/pcduino/pcduino8_uno_lib

• Clean and Compile the lib:

 cd pcduino8_uno_lib 
 make clean 
 make 
 sudo ./output/adc_test

• Input an analog signal on ADC0 channel

• The adc_test program will print the value of analog signal on ADC0 channel as default.

Create your own source code for ADC

Create new .c files in samples folder and modify Makefile to compile it. For example I want to create helloADC.c to read the values from all six ADC channels.

• Create helloADC.c source file

 vim samples/helloADC.c

 #include <core.h>
 int adc_id = 0;
 void setup()
 {
 }
 void loop()
 {
    for(adc_id=0; adc_id<6; adc_id++)
    {
         int value = analogRead(adc_id); // get adc value
       printf("ADC%d value is %d\n",adc_id, value);
        delay(1000); // wait for one sec
    }
 }

• Update Makefile

 vim samples/makefile

• Add a line after OBJS=… and add the name of your program (without suffix ‘.c’).

 

 OBJS = i2c_rtc_test spi_nfc_test adc_test led_test
 OBJS += uart_test
 OBJS += helloADC

• Compile and run:

 make
 sudo output/helloADC

Note: If you have not used the latest system image for pcDuino8 Uno, you have to use add sudo to access adc , the following content will tell you how to add permission for user linaro.

 sudo echo "SUBSYSTEM=="i2cdev", GROUP="i2c"" > /etc/udev/rules.d/90-i2c.rules
 sudo useradd linaro i2c
 sudo reboot