View source for ADC breakout board for pcDuino8 UNO


== Description ==

[[File:1-97.jpg]]

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).

[[File:1-98.png]]

=== 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

[[File:1-99.png]]

* 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