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GeoJoe
- 27th August 2008, 18:37
I've got a big one here. I can't get the TI DAC output to change. Here is my test code:
INTCON = %00000000 ' Enable TMR0 interrupts
INTCON2 = %10000000 ' ENABLES PORTB PULL UPS
'T0CON = %11010101 ' ENABLES TM0 AND SET PRESCALER
RCON = %00000000 ' IPEN RCON.7 INTERUPT PRIORITY LEVEL DISABLED
ADCON0 = %00000000 ' ATOD CH 4 CONVERTER ENABLED
ADCON1 = %01111111 ' All digital = 01111111
ADCON2 = %10000110 ' RIGHT JUST RESULT 0 TAD FOSC/64
OSCCON = %01101101 '

VOUTB VAR WORD

LOOP:
toggle porta.7
voutb = %0011010111111011
HIGH PORTB.5
PAUSEUS 2
low portb.5
shiftout portb.3,portb.2,5,[voutb\16]
HIGH PORTB.5
PAUSEUS 2
low portb.5
pause 1
shiftout portb.3,portb.2,5,[voutb\16]
HIGH PORTB.5
PAUSEUS 2
low portb.5
HIGH PORTA.0
PAUSE 5
LOW PORTA.0
pause 5
goto loop
END

PIC is running fine. 4 MHz internal clock right on time. Getting good bit stream and clock pulse.
Problem. I cannot get pin 18 PortA.7 to toggle or respond to HIGH or LOW pin commands. I tied on a pull up resistor, now it will not go low. Either way the DAC isn't listening. Just stays at mid scale so long as the CLR not pin is low.

GeoJoe
- 27th August 2008, 18:42
Here is the schematic

GeoJoe
- 27th August 2008, 18:50
Here is the spec sheet on the DAC
http://focus.ti.com/lit/ds/symlink/dac7553.pdf
Sorry for the hodge podge

amgen
- 28th August 2008, 03:07
you may have to set port a.7 to output,
just use .......
high portA.7 .......early-on

amgen

GeoJoe
- 28th August 2008, 14:39
I had it set to XT instead of INTRC. I had to set it in the configuration programmer menu drop down though. I thought I had it set correctly in the code. Oh well I'll start working on getting the DAC to respond now. I'll post any problems I encounter.

GeoJoe
- 28th August 2008, 20:29
VOUTB = 1000xxxxxxxxxxxx