Usage of built-in DAC ?

[CuriousOne]

Hello.

Certain PICs have built-in DAC. Is it possible somehow use it via picbasic?

[aratti]

Very simple for PIC16C782 you set the register DACON0 to ENABLE the dac and simply set the register DAC with a byte value for the analog output desired.

DAC = 128 will generate an analog output of 2.5 volts if your reference was Vdd (5V)

That's all.

Cheers

Al.

[CuriousOne]

So if I want alternating output, I have to update DAC register in the loop?

which statement will do that write?

[Demon]

Did you try DAC=255 for 100%?

(Or whatever register name is stated in datasheet)

I would stay from 0 to 255 (fits in 1 byte)

Robert

[Ruben Pena]

Hi:
I made this program and I can only get from 0 to 3.77 volts in the DAC output.

'************************************************* ***************
'* Name : EJERCICIO_16F1783.BAS *
'* Author : [select VIEW...EDITOR OPTIONS] *
'* Notice : Copyright (c) 2014 [select VIEW...EDITOR OPTIONS] *
'* : All Rights Reserved *
'* Date : 11/28/2014 *
'* Version : 1.0 *
'* Notes : *
'* : *
'************************************************* ***************
'************** CONFIG PARA 16F1782/83/84/86/88 *********************
#CONFIG
__config _CONFIG1, _FOSC_INTOSC & _MCLRE_ON & _CP_OFF & _CPD_OFF & _BOREN_ON & _CLKOUTEN_ON & _IESO_OFF & _FCMEN_OFF
__config _CONFIG2, _PLLEN_OFF & _LVP_OFF & _BORV_25 & _VCAPEN0_OFF & _VCAPEN1_OFF & _STVREN_OFF
#ENDCONFIG
@ ERRORLEVEL -306 ; turn off crossing page boundary message (dt)
@ ERRORLEVEL -305 ; turn off crossing page boundary message (dt)

'************************************************* ************************
'*********** REGISTER SETUP **********************************************
'************************************************* ************************
ANSELA = 01 'DESHAB ADC _INTRC_OSC_NOCLKOUT RA.0 PIN2
ANSELB = 0 'DESHABILITA ADC
'************* OPCIONES OSCILADOR INTERNO *******************************
OSCCON = $72 '$F8 int osc de 16 mhz $72 PARA 8 MHZ, $6A PARA 4 MHZ.
'************************************************* ************************
CM1CON0 = 0 'DESHAB. COMPARADORES 1
CM2CON0 = 0 ' Y 2
OPA1CON = 0 ' DESHABILITA OP AMPSX
OPA2CON = 0 ' DESHABILITA OP AMP
DACCON0 = $90 '1001 0000 DAC ENABLED,DACOUT2 ENABLED RB.7 PIN 28
CCP1CON = 0 ''NO COMPARE OR PWM
FVRCON = $00 'DISABLED
ADCON0 = $00
ADCON1 = $00
ODCONA = 0
ODCONC = 0
CMOUT = 0
DEFINE OSC 8
DEFINE ADC_BITS 8
DEFINE HSER_RCSTA 90H 'SERIAL INIT
DEFINE HSER_TXSTA 20H
DEFINE HSER_BAUD 1200
TRISA = $01 ' 0000 0001
TRISB = $00
TRISC = $80 '1000 0000
PORTA = 0
PORTB = 0
PORTC = 0
PAUSE 200

LED var porta.7
OUTSER VAR PORTC.6
VALOR VAR WORD
CHAR VAR BYTE
AUX VAR BYTE




START:
FOR AUX = 0 TO 4
LED = 1
PORTA = 255
PORTC = 255
PAUSE 500
LED = 0
PORTA = 0
PORTC = 0
PAUSE 500

NEXT AUX
HSEROUT ["PRUEBA A 8 MHZ",13,10]
FOR AUX = 0 TO $FF
DACCON1 = AUX 'send from 0 to 255 to DAC
HSEROUT ["AUX=",DEC3 AUX,13,10]
PAUSE 300
NEXT AUX
GOTO START
*****************************************
Somebody can tell me what I am doing wrong.?
Thanks in advance...
Ruben de la Pena

[Demon]

Are you checking voltage on pin A.2?

I see nothing, as long as you're checking B.7.

What happens if you move DACCON0 after the other registers, just before DEFINE OSC?

Maybe you are disabling DAC accidentally.

Robert

[Ruben Pena]

Robert: ¡¡¡ PROBLEM SOLVED ¡¡¡
The power supply is 5 V. I am checking Portb.7 because I config the DACCON0 as $90.
This enable the DAC and select Portb.7 as output.
I move the DACCON0 register as you suggest,but the result is the same.
Also I do not why,PORTA.6 remains lit when is making the voltage loop.
It is configured as output and I clear the port at the begginning.
I am using the EASYPIC V7 for development,and I realize I was loading
The portb with the panel Leds. I turnoff the led selection and now all is working OK.

Thanks for your comments...
Ruben de la Pena

[Demon]

Have you tried this?


LED var LATa.7

[Demon]

Why do this?


FOR AUX = 0 TO 4
LED = 1
PORTA = 255
PORTC = 255
PAUSE 500
LED = 0
PORTA = 0
PORTC = 0
PAUSE 500
NEXT AUX

Robert

[Ruben Pena]

Robert:
It works... the problem with Porta.6 was configuration. It was as oscilator output.
Changing & _CLKOUTEN_ON TO & _CLKOUTEN_OFF , in _CONFIG2 ,turn off the porta,6 and then
can be used as normal i/o port.
Thanks again...
Ruben de la Pena

Edited: I was testing the ports as IO.

Greetings...
Ruben de la Pena

[metemoine]

Very simple for PIC16C782 you set the register DACON0 to ENABLE the dac and simply set the register DAC with a byte value for the analog output desired.