16f753 DAC – 311 days old

[fofo]

16f753 Is there a DAC usage example?

[Les]

I don't have one of these devices, but the 9-bit DAC looks easy to setup and use, from reading the datasheet.

Here's a piece of code that you can copy and create an include file named "DAC.inc"

$ifndef __DAC_INC__
$define __DAC_INC__
'
' Routines to read and write the 9-bit DAC on a PIC16F753 device
' Auto sets up the DAC peripheral when the include file is used in the program
'
' Written by Les Johnson for the Proton BASIC compiler
' 
$define _DAC_Pin PORTA.0
'
' Create a 16-bit SFR from 2 8-bit SFRs
'    
    Dim wDAC1REF As DAC1REFL .Word
    Symbol DAC1REFLH = DAC1REFH 
    
'--------------------------------------------------------------------------------
' Initialise the DAC
' Input     : None
' Output    : None
' Notes     : DACOE enabled, DACFM right justified, DACEN enabled, DACPSS is VDD
'           : DAC1CON0bits_DACEN: DAC Enable bit
'               1 = DAC is enabled
'               0 = DAC is disabled
'             DAC1CON0bits_DACFM: DAC Output Format bit
'               1 = DAC output result is right justified
'               0 = DAC output result is left justified
'             DAC1CON0bits_DACOE: DAC Voltage Output Enable bit
'               1 = DAC voltage level is also an output on the DACOUT pin
'               0 = DAC voltage level is disconnected from the DACOUT pin
'             DAC1CON0bits_DACPSS1, DAC1CON0bits_DACPSS0: DAC Positive Source Select bits
'               11 = FVR output
'               10 = VREF+ pin
'               01 = OPA1OUT pin
'               00 = VDD
'
$define DAC_Initialise() '
    DAC1CON0 = $E0       '
    wDAC1REF = $0000     '
    Output _DAC_Pin
    
'--------------------------------------------------------------------------------
' Write 9-bit data into the DAC voltage reference control register.
' Input     : pValue holds the 9-bit data to write to the DAC
' Output    : None
' Notes     : None
'
$define DAC_Write(pValue) wDAC1REF = pValue
   
'--------------------------------------------------------------------------------
' Read 9-bit data from the DAC SFRs
' Input     : None
' Output    : Returns the 9-bit data from the DAC
' Notes     : None
'    
$define DAC_Read() wDAC1REF

'--------------------------------------------------------------------------------
_DAC_Main_:
    DAC_Initialise()        ' Initialise the DAC
    
$endif  ' __DAC_INC__

Here's a simple demo that works the DAC routines:

'
' A demo of the routines to control the 9-bit DAC on a 16F753 device
'
    Device = 16F753
    Declare Xtal = 8
  
    Include "DAC.inc"               ' Load the DAC peripheral routines into the program
    
    Dim wDAC_Value As Word
    
Main:
    Do                              ' Create a loop
        For wDAC_Value = 0 To 511   ' Create a loop for the 9-bits of data to send to the DAC
            DAC_Write(wDAC_Value)   ' Send the data to the DAC
            DelayMS 100             ' Slow things down so we can see the output alter
        Next                        ' Do it forever
    Loop

[acel]

Hi Les, I could not run 16F753 with the following program. What could be the reason?

Device = 16F753
Config FOSC0_INT,WDTE_OFF, PWRTE_ON , MCLRE_ON , BOREN_DIS , WRT_OFF, CP_ON, CLKOUTEN_OFF
OSCCON = 110100
 Declare Xtal =8
 Include "DAC753.inc"               ' Load the DAC peripheral routines into the program 

   All_Digital true
    TRISA=000000
    TRISC=000000 
    CM1CON0=0
    DAC1CON0=0
    FVR1CON0=0
    OPA1CON0=0
    SLPCCON0=0
    PORTA=0:PORTC=0 
    ANSELA = 000000 'All digital. A/D disabled
    ANSELC = 000000 'All digital. A/D disabled 
    CCP1CON = 000000
    APFCON=000000
'    Symbol SO = PORTA.2 
'Symbol CS = PORTA.0 
'Symbol SCK = PORTA.1
Symbol Led=PORTC.5
    Dim wDAC_Value As Word
    Dim M As Word
     Dim ISI As Word
     Dim x As Byte
     Dim z As Byte
     Clear
    
    
    
 init:  
       For z=0 To 20   
     DelayMS 200
     Toggle Led
         Next
Main:
      
      For wDAC_Value=0 To 511
                  DAC_Write (wDAC_Value)   ' Send the data to the DAC
               Next
            GoTo Main

[charliecoultas]

What happens when you try to run it?

[acel]

MCU does not respond at all.

[tumbleweed]

At a minumum, remove this line:

    DAC1CON0=0

You're overwriting the setup that's done by DAC_Initialise()

I would also leave the DAC output pin set to analog mode (but I think that may be done automatically)

[acel]

I think the problem stems from the compiler. LED do not even work.

[acel]

can be a problem in the 16F753 PPI file.

[Les]

Since Acel sent me a few 16F753 devices (many thanks), I have come up with the correction for the device with Proton.

Change the BANK0_START=0x00 to BANK0_START=0x20 in the device's PPI file. I've also done some tests for the DAC and here is a modified set of routines that write to the DAC, and work. :-)

Create a file named "DAC.inc" with the code below:

$ifndef __DAC_INC__
$define __DAC_INC__
'
'   /\\\\\\\\\
'  /\\\///////\\\
'  \/\\\     \/\\\                                                 /\\\          /\\\
'   \/\\\\\\\\\\\/        /\\\\\     /\\\\\\\\\\     /\\\\\\\\   /\\\\\\\\\\\  /\\\\\\\\\\\  /\\\\\\\\\
'    \/\\\//////\\\      /\\\///\\\  \/\\\//////    /\\\/////\\\ \////\\\////  \////\\\////  \////////\\\
'     \/\\\    \//\\\    /\\\  \//\\\ \/\\\\\\\\\\  /\\\\\\\\\\\     \/\\\         \/\\\        /\\\\\\\\\\
'      \/\\\     \//\\\  \//\\\  /\\\  \////////\\\ \//\\///////      \/\\\ /\\     \/\\\ /\\   /\\\/////\\\
'       \/\\\      \//\\\  \///\\\\\/    /\\\\\\\\\\  \//\\\\\\\\\\    \//\\\\\      \//\\\\\   \//\\\\\\\\/\\
'        \///        \///     \/////     \//////////    \//////////      \/////        \/////     \////////\//
'                                  Let's find out together what makes a PIC Tick!
'
' Routines to write to the 9-bit DAC on a 16F753 device
' Auto sets up the DAC peripheral when the include file is used in the program
'
' Written by Les Johnson for the Proton BASIC compiler
'
$define _DAC_Pin PORTA.0
'
' Create a 16-bit SFR from 2 8-bit SFRs
'
    Dim wDAC1REF As  DAC1REFL .Word
    Symbol DAC1REFLH = DAC1REFH

'--------------------------------------------------------------------------------
' Initialise the DAC
' Input     : None
' Output    : None
' Notes     : bit 7 DACEN: DAC Enable bit
'               1 = DACx is enabled
'               0 = DACx is disabled
'             bit 6 DACFM: DAC Output Format bit
'               1 = DACx output result is right justified
'               0 = DACx output result is left justified
'             bit 5 DACOE: DAC Voltage Output Enable bit
'               1 = DACx voltage level is also an output on the DACxOUT pin
'               0 = DACx voltage level is disconnected from the DACxOUT pin
'             bit 4 Unimplemented: Read as 0
'             bits 3-2 DACPSS<1:0>: DAC Positive Source Select bits
'               11 = FVR output
'               10 = VREF+ pin
'               01 = OPA1OUT pin
'               00 = VDD
'             bits 1-0 Unimplemented: Read as 0
'
$define DAC_Initialise() '
    Low _DAC_Pin         '
    wDAC1REF = $0066     '
    DAC1CON0 = $E0

'--------------------------------------------------------------------------------
' Write 16-bit data into the 9-bit DAC voltage reference control register.
' Input     : pValue holds the 16-bit data to write to the DAC
' Output    : None
' Notes     : Data is right justified
'
$define DAC_Write16(pValue)  '
    Clear DAC1CON0bits_DACFM '
    wDAC1REF = pValue

'--------------------------------------------------------------------------------
' Write 9-bit data into the DAC voltage reference control register.
' Input     : pValue holds the 9-bit data to write to the DAC
' Output    : None
' Notes     : Data is left justified
'
$define DAC_Write(pValue)  '
    Set  DAC1CON0bits_DACFM  '
    wDAC1REF = pValue

'--------------------------------------------------------------------------------
' Write 8-bit data into the 9-bit DAC voltage reference control register.
' Input     : pValue holds the 8-bit data to write to the DAC
' Output    : None
' Notes     : Data is right justified
'
$define DAC_Write8(pValue)   '
    Clear  DAC1CON0bits_DACFM  '
    DAC1REFL = pValue

'--------------------------------------------------------------------------------
_DAC_Main_:
    DAC_Initialise()        ' Initialise the DAC

$endif  ' __DAC_INC__

And use the code below as a demo for the DAC.inc file (above):

'
'   /\\\\\\\\\
'  /\\\///////\\\
'  \/\\\     \/\\\                                                 /\\\          /\\\
'   \/\\\\\\\\\\\/        /\\\\\     /\\\\\\\\\\     /\\\\\\\\   /\\\\\\\\\\\  /\\\\\\\\\\\  /\\\\\\\\\
'    \/\\\//////\\\      /\\\///\\\  \/\\\//////    /\\\/////\\\ \////\\\////  \////\\\////  \////////\\\
'     \/\\\    \//\\\    /\\\  \//\\\ \/\\\\\\\\\\  /\\\\\\\\\\\     \/\\\         \/\\\        /\\\\\\\\\\
'      \/\\\     \//\\\  \//\\\  /\\\  \////////\\\ \//\\///////      \/\\\ /\\     \/\\\ /\\   /\\\/////\\\
'       \/\\\      \//\\\  \///\\\\\/    /\\\\\\\\\\  \//\\\\\\\\\\    \//\\\\\      \//\\\\\   \//\\\\\\\\/\\
'        \///        \///     \/////     \//////////    \//////////      \/////        \/////     \////////\//
'                                  Let's find out together what makes a PIC Tick!
'
' A demo of the routines to control the 9-bit DAC on a 16F753 device
'
    Device = 16F753
    Declare Xtal= 8
    Declare Optimiser_Level= 1

    OSCCON = $30                        ' Internal Oscillator Frequency select to 8MHz
    Repeat: Until  OSCCONbits_HTS  = 1    ' Wait for oscillator stability

    Include "DAC.inc"                   ' Load the DAC peripheral routines into the program

    Dim wDAC_Value As Word              ' Holds the value to send to the DAC

'----------------------------------------------
Main:
    Do                                  ' Create an infinite loop
        For wDAC_Value = 0 To 511       ' Create a loop for the 9-bits of data to send to the DAC
            DAC_Write(wDAC_Value)       ' Send the data to the DAC
            DelayMS 100                 ' Slow things down so we can see the output alter
        Next
    Loop                                ' Do it forever

'----------------------------------------------
' Configure the fuses
'
    Config FOSC0_INT, CLKOUTEN_OFF, WDTE_OFF, PWRTE_ON, MCLRE_ON, BOREN_DIS, WRT_OFF, CP_OFF 

Note that the DAC output does not supply much current, so a buffer will be required to power anything. So don't expect an LED to illuminate from it without an op-amp buffer between them.