----- Original Message ----- From: Paul Erkiert To: pic microcontroller discussion list Sent: Sunday, January 28, 2001 8:06 PM Subject: Re: [PIC]: Homemade Programmer 16F877 > Hi Jeethu > Just use one or two silicon diodes between the middle pin(earth) and the 0v > rail this will "Lift" the voltage by 0.6volts each so 1.2v if using two. > The other way is to Cascade an 8volt from a 5volt reg so that the middle pin > of the 8 volt reg is at 5 volts then you should have 13volts. > I am using a "clasic" Tait programmer for the 16f877 and using Nigle > Goodwins WPICPROG877 > http://www.ipilsley.co.uk/software/ > Its built on veroboard I find that its good but the picprog seems always > to set code protect so have to just uncheck it before burning. > My other "HOT TIP" or really silly mistake I made while using the 877 was > assuming it was ok not to set ADCON1 ,I hear the experts laugth but you need > to set it if you want only Digital ports > movlw B'00000110' ;all digital Note this has to be set > movwf ADCON1 ^0x80 ; > also the tris bits of port E Bit 4 to 7 need to be set correctly. > Good Luck > Paul > paul@g4bks.fsnet.co.uk > > > ----- Original Message ----- > From: Jeethu Rao > To: > Sent: Saturday, January 27, 2001 10:41 AM > Subject: [PIC]: Homemade Programmer 16F877 > > > Hi guys, > > My PIC Start Plus stopped working a week back and I decided to construct a > home made programmer for programming 16f877s. I checked the PicList pages > and I could not find a single schematic for a 16f877 programmer ! almost all > the programmers were for 16F84. > > So, I decided to construct my own programmer. And I set out. I took David > Tait's TOPIC as the reference design. > > TOPIC uses a LM 317 to get the high voltage (12 to 14 volts as Microchip > says). I want to use a 7812 12 volts regulator instead of a 317. > > When I checked the output of a 7812 in an existing circuit with a DMM, it > showed 11.9 volts. > > Now, my question to the experienced gentlemen on PicList is weather I can > program a PIC using 11.9 volts for the VPP > (Programming voltage) ? > > Regards, > > Jeethu Rao > > -- > http://www.piclist.com hint: PICList Posts must start with ONE topic: > [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads > > > > -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.