18F4550 issue with simple program.

[jmgelba]

I'm having a problem getting a really simple program to run on an 18F4550. It just a couple of blinky LED's to verify the PIC is alive. I can program it fine and read back from the device but cannot get this program to work.

I'm running this on a 20mhz resonator using HS+PLL with PLL/5. MCLR is disabled, low voltage programming disabled. What am I missing?!

Define OSC 48
Define ADC_BITS 10 ' Set number of bits in result
Define ADC_CLOCK 3 ' Set clock source (3=rc)
Define ADC_SAMPLEUS 50 ' Set sampling time in uS
adval var word ' Create adval to store result

TRISA = %11111111 ' Set PORTA to all input
ADCON1 = %10001111 ' Set PORTA analog and right justify result
TRISB = %00000000
TRISC = %00000000

RCSTA.7 = 0

loop1:
Portc.6 = 1
pause 100
Portc.7 = 1
pause 200
portc.6 = 0
portc.7 = 0
pause 200
goto loop1
End

[Scampy]

deleted after posting

[richard]

you might need another read of the hardware manual for a 18F4550


ADCON1 = %10001111 ' Set PORTA analog and right justify result ?????????????


sets all analogue pins digital

you need
ADCON1 = %00001010 'Set PORTA analog
ADCON2.7=1 ' right justify result

ps

where does this bogus line come from
ADCON1 = %10001111 ' Set PORTA analog and right justify result ?????????????
it comes up repeatedly

[jmgelba]

Yes you're right. I hadnt changed the comment but the setting is correct for what I need. Still, It is not running. I've noticed that the code is being loaded into the end of the program space and not the beginning. Is this an issue and how do I resolve it if it is?

I'm using PBP 2.60A, MCS 3.0.0.5 and MPLAB 8.20A

[Mike2545]

Is MCLR tied high?

[Scampy]

Not sure if this helps, but this is a section of code that uses an 18f4580, with four pots on port A

; config settings 18F2550/4550/18F4580, 20mhz crystal
ASM  
  __CONFIG    _CONFIG1H, _OSC_HSPLL_1H
  __CONFIG    _CONFIG2L, _PWRT_ON_2L  
  __CONFIG    _CONFIG2H, _WDT_ON_2H & _WDTPS_512_2H
  __CONFIG    _CONFIG3H, _PBADEN_OFF_3H
  __CONFIG    _CONFIG4L, _LVP_OFF_4L & _XINST_OFF_4L
ENDASM

DEFINE  OSC 48
ADCON1 = $0F
clear


DEFINE ADC_BITS 10                              ' Set-up ADC for fastest 10-bit results
DEFINE ADC_CLOCK 2
DEFINE ADC_SAMPLEUS 5
INCLUDE "DT_Analog.pbp"

MaxSetPoint  CON 500                            ' Pot fully clockwise - gives max setting 50 degrees
MinSetPoint  CON 100                            ' Pot fully counter clockwise - sets min setting 10 degrees
ADbits = 14                                     ' set A/D resolution to 14-bits
CMCON = 7                                       ' disable Comparators
ADCON1 = %00001011                              ' sets up Analogue pins
ADCON2.7 = 1                                    ' ADFM bit isn't in ADCON1 anymore

;----[Port settings]----------------------------------------------------

TRISA = %11001111

It uses DT's analogue include file, which might be worth downloading and including in your own code

[jmgelba]

Is MCLR tied high?

No. Does the PicKit 3 programmer hold it high or low when powering the target board?

I do have it disabled in the config bits.