Jim, Disregard the comment about using the scope as I reread your post and see that you have already tried using a scope to see any activity. Not suggesting that it isn't, but make sure your scope is set up correctly to see the signals. Regards, Jim > -------- Original Message -------- > Subject: RE: PIC16F876A not changing output pins > From: > Date: Thu, March 03, 2011 10:19 am > To: "Microcontroller discussion list - Public." >=20 >=20 > Jim, >=20 > I see you are using the INTRCOSC, and I assume it defaults to 4mhz > since I don't see any frequency setting code. So, if that is the case, > the only thing I can see that might be an issue is that you are > switching > PORTB on and off at about a 1 MHZ rate, so if you have LED's connected, > all you'll probably see is a Dim LED brightness. Look at the pins with > a scope to see if they are actually toggling. Or add a delay after you > tunr PORTB on, and again after you turn it OFF so you have time to see > if they are toggling. >=20 > Regards, >=20 > Jim >=20 > > -------- Original Message -------- > > Subject: PIC16F876A not changing output pins > > From: Jim > > Date: Thu, March 03, 2011 10:05 am > > To: piclist > >=20 > >=20 > > Hello, I am having trouble with a PIC16F876A, on an Olimex 28-pin dev b= oard > > (see http://www.sparkfun.com/products/18). The program downloads and > > verifies successfully (or so the software tells me) via an meLabs U2 US= B > > programmer. In the past, I've had a couple PIC18 chips partially die o= n me > > without losing their ability to be programmed, so I'm wondering if that= 's > > the case here, or if there's something wrong with my code. I have been > > careful about grounding myself while handling both chips, although it's > > possible that I forgot at some point while working on it with little sl= eep. > >=20 > >=20 > > I am trying to toggle all the pins of PORTB as a "hello world" test. I= t > > works in the simulator, but apparently does nothing on the board. I ha= ve > > already checked the supply voltage (+5.05V) and tested both chips on a > > breadboard with all the I/O ports connected to GND with 1k resistors as > > suggested here http://www.piclist.com/techref/logic/xtrapins.htm. Stil= l > > nothing on my scope. Here is my assembly code: > >=20 > > list p=3D16f876a ; list directive to define processor > > #include "p16f876a.inc" ; processor specific variable definition= s > > __CONFIG _CP_OFF & _WDT_OFF & _BODEN_ON & _PWRTE_ON & _RC_OSC & _LVP_O= FF & > > _DEBUG_OFF & _CPD_OFF > >=20 > > ; '__CONFIG' directive is used to embed configuration data within .asm = file. > > ; The lables following the directive are located in the respective .inc > > file. > > ; See respective data sheet for additional information on configuration > > word. > >=20 > > ;***** VARIABLE DEFINITIONS > > ;; w_temp EQU 0x70 ; variable used for context saving > > ;; status_temp EQU 0x71 ; variable used for context saving > >=20 > > ;********************************************************************** > > ORG 0x000 ; processor reset vector > > clrf PCLATH ; ensure page bits are cleared > > ; goto main ; > >=20 > >=20 > > ;; initialize PORTA > > bcf STATUS, RP0 ; select bank 0 > > bcf STATUS, RP1 > > clrf PORTB > >=20 > > bsf STATUS, RP0 ; select bank 1 > > movlw 0x06 > > movwf ADCON1 > > movlw 0x00 > > movwf TRISB > >=20 > > top: > > bcf STATUS, RP0 ; select bank 0 > > movlw 0x00 > > movwf PORTB > > movlw 0xFF > > movwf PORTB > > goto top > > END ; directive 'end of program' > >=20 > > Is there something wrong with this code, or is it definitely a hardware > > issue? > >=20 > > Thanks, > > Jim > > --=20 > > http://www.piclist.com PIC/SX FAQ & list archive > > View/change your membership options at > > http://mailman.mit.edu/mailman/listinfo/piclist --=20 http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .