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PIC12F1822 DAC Module

This small post shows how to start using PIC12F1822 DAC (Digital-to Analog Converter) module. PIC12F1822 microcontroller has 1 DAC module. The DAC can be used to supply analog voltage on RA0 pin with 32 selectable output levels.

Tags: #converter#output#voltage
Ibrar Ayyub By Ibrar Ayyub
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CategoryPeripheral Tutorials
PIC modelPIC12F1822
Reading time~3 min

Summary of PIC12F1822 DAC Module

This article explains how to initialize and control the Digital-to-Analog Converter (DAC) module on the PIC12F1822 microcontroller using the CCS PIC C compiler. It details configuration modes, voltage sources (VDD, VREF, FVR), and the use of `setup_dac` and `dac_write` functions to generate analog output levels on the RA0 pin.

Parts used in the PIC12F1822 DAC Project:

  • PIC12F1822 Microcontroller
  • DAC Module
  • RA0 Pin
  • VSS Supply Voltage
  • VDD Supply Voltage
  • VREF Pins
  • FVR (Fixed Voltage Reference)
  • CCS PIC C Compiler

PIC12F1822 DAC Module
The input of the DAC can be connected to:

  • External VREF pins
  • VDD supply voltage
  • FVR (Fixed Voltage Reference)

DAC Block diagram is shown below:

With CCS PIC C compiler we can initialize the DAC module using the following command:
setup_dac(int8 mode);
Where mode can one of the following modes:
DAC_OFF  0                                            // DAC disabled
DAC_VSS_VDD                                      // Negative source is VSS and positive source is VDD
DAC_VSS_VREF                                    // Negative source is VSS and positive source is Vref+ pin
DAC_VSS_FVR                                      // Negative source is VSS and positive source is FVR (Fixed Voltage Reference)
The DAC output can be enabled using the following line which or'ed with above in setup_dac() using |.
DAC_OUTPUT                                       // Enable ADC output on RA0 pin.
Controlling the output of the DAC is also easy with CCS PIC C compiler and for that we have to use the following command:
dac_write(int8 value);
Where value should be a 5-bit number which varies between 0 and 31.
The DAC output voltage is determined by the following equation assuming that the DAC is enabled (DACEN bit is 1):

The DAC 32 levels are set with DACR[4:0] bits which is done using dac_write() command.
Assume that we've PIC12F1822 microcontroller with +5V power supply, the DAC is configured with VSS and VDD as negative and positive sources and the DAC output is enabled.
Minimum Vout voltage when DACR[4 : 0] = 0b00000 equals to 0V.
Maximum Vout voltage when DACR[4 : 0] = 0b11111 equals to 4.84V
Writing DACR[4 : 0] = 0b00000 is done using: dac_write(0);
And DACR[4 : 0] = 0b11111 is dac_write(31);

PIC12F1822 DAC Module Example:
This is a small example for the DAC module. Example circuit schematic is shown below.

Read more: PIC12F1822 DAC Module 

  • How many DAC modules does the PIC12F1822 have?
    The PIC12F1822 microcontroller has one DAC module.
  • What are the possible input sources for the DAC?
    The input can be connected to External VREF pins, VDD supply voltage, or FVR.
  • Which command initializes the DAC module in CCS PIC C compiler?
    The setup_dac(int8 mode) command is used to initialize the module.
  • How do you enable the DAC output on the RA0 pin?
    You enable it by ORing the DAC_OUTPUT flag with the mode in the setup_dac() function.
  • What value range is required for the dac_write function?
    The value must be a 5-bit number varying between 0 and 31.
  • How is the maximum output voltage calculated in a +5V system?
    With VSS and VDD sources, the maximum voltage at dac_write(31) equals 4.84V.
  • What is the minimum output voltage when the DAC is enabled?
    The minimum voltage is 0V when DACR[4 : 0] is set to 0b00000.
  • How many selectable output levels does the DAC provide?
    The DAC provides 32 selectable output levels.
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Ibrar Ayyub

Ibrar Ayyub

I am an experienced technical writer holding a Master's degree in computer science from BZU Multan, Pakistan University. With a background spanning various industries, particularly in home automation and engineering, I have honed my skills in crafting clear and concise content. Proficient in leveraging infographics and diagrams, I strive to simplify complex concepts for readers. My strength lies in thorough...