Post by thread:[PIC:] Trouble with GP3 on 12F675

I've been struggling to figure out why I can set GP1, GP2, GP4 and GP5 without trouble but I can't get GP3 to set. Set meaning I can't get it to go high and turn on an LED. I'm using a 12F675. I suspect it has something to do with my config bits because MCLR is on GP3. Here's the simple program I wrote. I'm hoping someone can help me spot my bug. Thanks. ; test1 list p=12F675 #include <p12f675.inc> __CONFIG _CP_OFF & _WDT_OFF & _BODEN_ON & _PWRTE_ON & _INTRC_OSC_NOCLKOUT & _MCLRE_OFF & _CPD_OFF #define Bank0 0x00 #define Bank1 0x80 cblock 0x20 ncount mcount ocount endc ORG 0x000 nop goto Init ORG 0x004 return Init banksel Bank1 movwf OSCCAL movlw B'00000001' ; set direction so all pins except GP0 are output pins movwf TRISIO ; so GP0 is input pin movlw b'00010001' movwf ANSEL ; make GP0 (AN0) be analog input and Fosc/8 for A/D conversion clock banksel Bank0 movlw b'111' movwf CMCON ; disable comparator movlw b'00000001' ; movwf ADCON0 ; Select AN0 as a2d channel, Left justified & enables A/D NOP ; Give 4 uS delay before starting A/D NOP NOP NOP bsf ADCON0,GO ; Start A/D Main call NOon call delay call GP1on call delay call NOon call delay call GP2on call delay call NOon call delay call GP3on call delay call NOon call delay call GP4on call delay call NOon call delay call GP5on call delay goto Main NOon movlw b'00000000' movwf GPIO return GP1on movlw b'00000010' movwf GPIO return GP2on movlw b'00000100' movwf GPIO return GP3on movlw b'00001000' movwf GPIO return GP4on movlw b'00010000' movwf GPIO return GP5on movlw b'00100000' movwf GPIO return delay movlw 0x10 movwf mcount loadn movlw 0xFF movwf ncount loado movlw 0xFF movwf ocount repeat decfsz ocount,f goto repeat decfsz ncount,f goto loado decfsz mcount,f goto loadn return END __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com

>-----Original Message----- >From: spam_OUTpiclist-bouncesTakeThisOuTmit.edu [.....piclist-bouncesKILLspam@spam@mit.edu] >Sent: 03 August 2005 08:10 >To: piclistKILLspammit.edu >Subject: [PIC:] Trouble with GP3 on 12F675 > > >I've been struggling to figure out why I can set GP1, GP2, GP4 >and GP5 without trouble but I can't get GP3 to set. Set >meaning I can't get it to go high and turn on an LED. I'm >using a 12F675. I suspect it has something to do with my >config bits because MCLR is on GP3. Here's the simple program >I wrote. I'm hoping someone can help me spot my bug. Thanks. The bug is that you didn't read page 22 of the datasheet! GP3 is an input pin only. Regards Mike ======================================================================= This e-mail is intended for the person it is addressed to only. The information contained in it may be confidential and/or protected by law. If you are not the intended recipient of this message, you must not make any use of this information, or copy or show it to any person. Please contact us immediately to tell us that you have received this e-mail, and return the original to us. Any use, forwarding, printing or copying of this message is strictly prohibited. No part of this message can be considered a request for goods or services. =======================================================================

I suspect that is input only type of pin. You still can try manipulate it by switching pull ups on and off. laura capaldi wrote: {Quote hidden}> > I've been struggling to figure out why I can set GP1, GP2, GP4 and GP5 without trouble but I can't get GP3 to set. Set meaning I can't get it to go high and turn on an LED. I'm using a 12F675. I suspect it has something to do with my config bits because MCLR is on GP3. Here's the simple program I wrote. I'm hoping someone can help me spot my bug. Thanks. > > ; test1 > list p=12F675 > #include <p12f675.inc> > __CONFIG _CP_OFF & _WDT_OFF & _BODEN_ON & _PWRTE_ON & _INTRC_OSC_NOCLKOUT & _MCLRE_OFF & _CPD_OFF > #define Bank0 0x00 > #define Bank1 0x80 > cblock 0x20 > ncount > mcount > ocount > endc > ORG 0x000 > nop > goto Init > ORG 0x004 > return > Init > banksel Bank1 > movwf OSCCAL > movlw B'00000001' ; set direction so all pins except GP0 are output pins > movwf TRISIO ; so GP0 is input pin > movlw b'00010001' > movwf ANSEL ; make GP0 (AN0) be analog input and Fosc/8 for A/D conversion clock > banksel Bank0 > movlw b'111' > movwf CMCON ; disable comparator > movlw b'00000001' ; > movwf ADCON0 ; Select AN0 as a2d channel, Left justified & enables A/D > NOP ; Give 4 uS delay before starting A/D > NOP > NOP > NOP > bsf ADCON0,GO ; Start A/D > Main > call NOon > call delay > call GP1on > call delay > call NOon > call delay > call GP2on > call delay > call NOon > call delay > call GP3on > call delay > call NOon > call delay > call GP4on > call delay > call NOon > call delay > call GP5on > call delay > goto Main > NOon > movlw b'00000000' > movwf GPIO > return > > GP1on > movlw b'00000010' > movwf GPIO > return > GP2on > movlw b'00000100' > movwf GPIO > return > GP3on > movlw b'00001000' > movwf GPIO > return > GP4on > movlw b'00010000' > movwf GPIO > return > GP5on > movlw b'00100000' > movwf GPIO > return > delay > movlw 0x10 > movwf mcount > loadn > movlw 0xFF > movwf ncount > loado > movlw 0xFF > movwf ocount > repeat > decfsz ocount,f > goto repeat > decfsz ncount,f > goto loado > decfsz mcount,f > goto loadn > return > > END > > __________________________________________________ > Do You Yahoo!? > Tired of spam? Yahoo! Mail has the best spam protection around > http://mail.yahoo.com > -

This behavior is common to the PICs with both internal RC oscillator and internal MCLR pin options. In this case, the MCLR pin can be an input only pin if internal MCLR option is used, but not an ouput pin. Examples: 10F20x, 12F508/509, 16F505, 12F629/675/683/635, 16F630/676/684/688/636, 16F631/677/685/687/689/785, PIC16F91x, etc Recently Microchip is more careful about the description of the I/O pins. For example, in the PIC16F785 datasheet, it is written in Page 1 that it has "17 I/O pins and 1 input-only pin". Regards, Xiaofan ---------------------------------------------- Xiaofan Chen R&D Engineer, Photoelectric Sensor Development Pepperl+Fuchs Singapore http://www.pepperl-fuchs.com Signals for the world of automation -------------------------------------------- {Original Message removed}

On 8/3/05, Dmitriy Kiryashov <.....vze27bymKILLspam.....verizon.net> wrote: > I suspect that is input only type of pin. > You still can try manipulate it by switching > pull ups on and off. Nice ! Vasile {Quote hidden}> > > > laura capaldi wrote: > > > > I've been struggling to figure out why I can set GP1, GP2, GP4 and GP5 without trouble but I can't get GP3 to set. Set meaning I can't get it to go high and turn on an LED. I'm using a 12F675. I suspect it has something to do with my config bits because MCLR is on GP3. Here's the simple program I wrote. I'm hoping someone can help me spot my bug. Thanks. > > > > ; test1 > > list p=12F675 > > #include <p12f675.inc> > > __CONFIG _CP_OFF & _WDT_OFF & _BODEN_ON & _PWRTE_ON & _INTRC_OSC_NOCLKOUT & _MCLRE_OFF & _CPD_OFF > > #define Bank0 0x00 > > #define Bank1 0x80 > > cblock 0x20 > > ncount > > mcount > > ocount > > endc > > ORG 0x000 > > nop > > goto Init > > ORG 0x004 > > return > > Init > > banksel Bank1 > > movwf OSCCAL > > movlw B'00000001' ; set direction so all pins except GP0 are output pins > > movwf TRISIO ; so GP0 is input pin > > movlw b'00010001' > > movwf ANSEL ; make GP0 (AN0) be analog input and Fosc/8 for A/D conversion clock > > banksel Bank0 > > movlw b'111' > > movwf CMCON ; disable comparator > > movlw b'00000001' ; > > movwf ADCON0 ; Select AN0 as a2d channel, Left justified & enables A/D > > NOP ; Give 4 uS delay before starting A/D > > NOP > > NOP > > NOP > > bsf ADCON0,GO ; Start A/D > > Main > > call NOon > > call delay > > call GP1on > > call delay > > call NOon > > call delay > > call GP2on > > call delay > > call NOon > > call delay > > call GP3on > > call delay > > call NOon > > call delay > > call GP4on > > call delay > > call NOon > > call delay > > call GP5on > > call delay > > goto Main > > NOon > > movlw b'00000000' > > movwf GPIO > > return > > > > GP1on > > movlw b'00000010' > > movwf GPIO > > return > > GP2on > > movlw b'00000100' > > movwf GPIO > > return > > GP3on > > movlw b'00001000' > > movwf GPIO > > return > > GP4on > > movlw b'00010000' > > movwf GPIO > > return > > GP5on > > movlw b'00100000' > > movwf GPIO > > return > > delay > > movlw 0x10 > > movwf mcount > > loadn > > movlw 0xFF > > movwf ncount > > loado > > movlw 0xFF > > movwf ocount > > repeat > > decfsz ocount,f > > goto repeat > > decfsz ncount,f > > goto loado > > decfsz mcount,f > > goto loadn > > return > > > > END > > > > __________________________________________________ > > Do You Yahoo!? > > Tired of spam? Yahoo! Mail has the best spam protection around > > http://mail.yahoo.com > > --