Post by thread:(Fwd) No life from 16c84

I wrote the listing below and it assembled fine and it runs on the microchip simulator. I have programmed the 16c84 with the serial programmer and the code reads back fine which confirms that it has been programmed but when I put the PIC in circuit nothing happens. I am holding the MCLR line high and am using a 4MHz crystal with 15p capacitors to ground and LEDs on port b outputs. Is this circuit correct and does the code check out ok? (reset vector etc.?) Any help would be appreciated. (If I can't get this working, there's not much hope for anything more advanced!) count1 equ 0C count2 equ 0D portb equ 06 org 0 init movlw 0 tris portb ; set as outputs movwf portb ; set portb levels all low start bsf portb,0 ; set working reg bit 0 high rot_L call wait rlf portb,same btfss portb,7 goto rot_L rot_R call wait rrf portb,same btfss portb,0 goto rot_R goto rot_L ; ---------------------------- ; wait subroutine ; ---------------------------- wait movlw .4 ; load count1 with decimal 4 movwf count1 d1 movlw .100 ; load count2 with decimal 100 movwf count2 d2 decfsz count2,same ; decrement and skip next line if zero goto d2 ; if not zero decfsz count1 ; decrement count1 if count2 is zero goto d1 ; do inside loop again if count2 nz retlw 00 ; ---------------------------- END -- /\/\att.

You wrote: > >I wrote the listing below and it assembled fine and it runs on the >microchip simulator. > >I have programmed the 16c84 .... when I put the PIC in circuit >nothing happens. > >I am holding the MCLR line high and am using a 4MHz crystal with 15p >capacitors to ground and LEDs on port b outputs. > >Is this circuit correct and does the code check out ok? (reset vector etc.?) > > .... > movlw 0 > tris portb ; set as outputs > .... Matt: Ignore the guy telling you to switch register pages; your code will work just fine. My guess is that either the oscillator isn't working or that you haven't turned off the Watchdog Timer. -Andy -- Andrew Warren - spam_OUTfastfwdTakeThisOuTix.netcom.com Fast Forward Engineering, Vista, California

{Quote hidden}>I wrote the listing below and it assembled fine and it runs on the microchip >simulator. >I have programmed the 16c84 with the serial programmer and the code reads back > fine >which confirms that it has been programmed but when I put the PIC in circuit > nothing >happens. >I am holding the MCLR line high and am using a 4MHz crystal with 15p >capacitors > to >ground and LEDs on port b outputs. > >Is this circuit correct and does the code check out ok? (reset vector etc.?) > > >Any help would be appreciated. (If I can't get this working, there's not much > hope >for anything more advanced!) > >count1 equ 0C >count2 equ 0D >portb equ 06 > > org 0 > >init > movlw 0 > tris portb ; set as outputs > movwf portb ; set portb levels all low > >start > bsf portb,0 ; set working reg bit 0 high > > >rot_L call wait > rlf portb,same > btfss portb,7 > goto rot_L > >rot_R call wait > rrf portb,same > btfss portb,0 > goto rot_R > goto rot_L > >; ---------------------------- >; wait subroutine >; ---------------------------- >wait > movlw .4 ; load count1 with decimal 4 > movwf count1 >d1 movlw .100 ; load count2 with decimal 100 > movwf count2 >d2 decfsz count2,same ; decrement and skip next line if zero > goto d2 ; if not zero > decfsz count1 ; decrement count1 if count2 is zero > goto d1 ; do inside loop again if count2 nz > retlw 00 >; ---------------------------- > >END > > > > >-- >/\/\att. > > Matt, The code looks fine. The problem must be in the hardware or to do with the programmer. The Xtal/cap combo is right, I use the same. Try forcing a reset by pulling MCLR low. ( the power up time may be to slow for the pic's internal reset) . Check that the leds are the right way around. Check the WDT is OFF but even so you still should have a couple of seconds before reset because the WDT default is maximum setting. Check that you are loading the right type if hex file into the programmer. If memory serves, it is possible to load the wrong hex format and programmers can't detect the error. If the wrong file type is loaded and accepted, it will program and verify as being correct. Quit the programmer, reload it and read the device again, this is the only way to test that the programmer is really working. Compare the results against the program listing. Good luck, you seem to be on the right track. Everyone has these hassles at the beginning! Regards, Jim Robertson P.S Sorry about the delay, the first reply bounced. ----------------------------------------------------------------- NEWFOUND ELECTRONICS, Makers of low cost, mega featured PIC programming tools. .....newfoundKILLspam@spam@ne.com.au ------------------------------------------------------------------

>To: pic microcontroller discussion list <PICLISTKILLspamMITVMA.BITNET> >From: .....stephnssKILLspam.....mail.pyrotechnics.com >Subject: Re: (Fwd) No life from 16c84 > >>I wrote the listing below and it assembled fine and it runs on the microchip >>simulator. >>I have programmed the 16c84 with the serial programmer and the code reads back >> fine >>which confirms that it has been programmed but when I put the PIC in circuit >> nothing >>happens. >>I am holding the MCLR line high and am using a 4MHz crystal with 15p capacitors {Quote hidden}>> to >>ground and LEDs on port b outputs. >> >>Is this circuit correct and does the code check out ok? (reset vector etc.?) >> >> >>Any help would be appreciated. (If I can't get this working, there's not much >> hope >>for anything more advanced!) > >Your code ran for me. >I am using Rasi's PIP-02 release 1.03 programmer with com84 drivers with a PC's serial port, the latest MPASM assembler, which gave me 22 errors when I assembled your code. >I made the following changes: >;************************************************************************** ***** >LIST p=16C84 ;target processor ;Tell MPASM you'v e got a C84 PIC >_CP_OFF EQU H'3FFF' ;code protect off >_PWRTE_ON EQU H'3FFF' ;Power on timer on >_WDT_OFF EQU H'3FFB' ;watch dog timer off >_XT_OSC EQU H'3FFD' ;crystal oscillator >__CONFIG _CP_OFF & _PWRTE_ON & _WDT_OFF & _XT_OSC ;configure direct ive > >same equ 1 ;VERY IMPORTANT! put variables in register, NOT W. >;************************************************************************** ***** >I used a 32KHz quartz crystal and watched a few LED's scan back & forth. Pretty cool :) >At 4 MHz with your timer parameters, they would all appear partialy lit. > >