Post by thread:[PIC]: ICD2 drive capability

Hi, Does anyone have any information on the drive capability of the MPLAB ICD2? For some reason, every time I install the RAM (or the ABT245 bus-buffer that I put on PortB) onto my target board, the ICD either fails to detect the PIC (a 16F877A) or detects the PIC but fails to program/verify it. R_rst is an 11k from Vcc to !MCLR. There are no capacitors or resistors on the PGD and PGC lines - just ICs. The RAM is a Brilliance Semiconductor BS62LV1024, and the bus buffer is a Texas Instruments SN74ABT245A. The schematic's online at <http://philpem.castlecore.com/eprem.png>. I know I've probably done something damn stupid, but I can't see what :-/ Thanks, -- Phil. | Acorn Risc PC600 Mk3, SA202, 64MB, 6GB, spam_OUTphilpemTakeThisOuTphilpem.me.uk | ViewFinder, 10BaseT Ethernet, 2-slice, http://www.philpem.me.uk/ | 48xCD, ARCINv6c IDE, SCSI ... Psychoceramics: The study of crackpots.

Here's a thought... It looks like the PIC is controlling the OE line of your RAM, when the PIC is in reset or being programmed, is it possible that the OE line is floating high and conflicting with the programmer? A pull down resistor might be all you need to solve it. -Denny > Hi, > Does anyone have any information on the drive capability of the MPLAB ICD2? > For some reason, every time I install the RAM (or the ABT245 bus-buffer that > I put on PortB) onto my target board, the ICD either fails to detect the PIC > (a 16F877A) or detects the PIC but fails to program/verify it. > R_rst is an 11k from Vcc to !MCLR. There are no capacitors or resistors on > the PGD and PGC lines - just ICs. The RAM is a Brilliance Semiconductor > BS62LV1024, and the bus buffer is a Texas Instruments SN74ABT245A. > > The schematic's online at <http://philpem.castlecore.com/eprem.png>. I know > I've probably done something damn stupid, but I can't see what :-/ > > Thanks, > -- > Phil. | Acorn Risc PC600 Mk3, SA202, 64MB, 6GB, > .....philpemKILLspam@spam@philpem.me.uk | ViewFinder, 10BaseT Ethernet, 2-slice, > http://www.philpem.me.uk/ | 48xCD, ARCINv6c IDE, SCSI > ... Psychoceramics: The study of crackpots. > --

In message <000601c56a00$37f255e0$16401545@me> "Denny Esterline" <firmwareKILLspamtds.net> wrote: > Here's a thought... It looks like the PIC is controlling the OE line of your > RAM, when the PIC is in reset or being programmed, is it possible that the > OE line is floating high and conflicting with the programmer? A pull down > resistor might be all you need to solve it. Way ahead of you - I've pulled the RAM chip, but if the output buffers are powered up (TGTVCC = Vcc = +5V), the ICD detects the PIC but fails to program it. If I float TGTVCC, the PIC programs fine... Just for extra points, the RS232 hardware seems to be acting up too.. *sigh* Also, there's an error on that schematic - I'm using an 11.0592MHz xtal, not a 10MHz xtal. Thanks, -- Phil. | Acorn Risc PC600 Mk3, SA202, 64MB, 6GB, .....philpemKILLspam.....philpem.me.uk | ViewFinder, 10BaseT Ethernet, 2-slice, http://www.philpem.me.uk/ | 48xCD, ARCINv6c IDE, SCSI ... An ulcer is what you get mountain climbing over molehills

> The schematic's online at > <http://philpem.castlecore.com/eprem.png>. I > know > I've > probably done something damn stupid, but I can't > see what :-/ Where is your LVP (PGM pin) pull-down? Wouter van Ooijen -- ------------------------------------------- Van Ooijen Technische Informatica: http://www.voti.nl consultancy, development, PICmicro products docent Hogeschool van Utrecht: http://www.voti.nl/hvu

In message <000c01c56a0d$396b4e60$0b00a8c0@PAARD> "Wouter van Ooijen" <EraseMEwouterspam_OUTTakeThisOuTvoti.nl> wrote: > Where is your LVP (PGM pin) pull-down? I thought that was only required if you were using LVP... -- Phil. | Acorn Risc PC600 Mk3, SA202, 64MB, 6GB, philpemspam_OUTphilpem.me.uk | ViewFinder, 10BaseT Ethernet, 2-slice, http://www.philpem.me.uk/ | 48xCD, ARCINv6c IDE, SCSI ... Spill a drink on your hard drive? Try PC Towels..

Phil, On Sun, 05 Jun 2005 19:28:58 +0100, Philip Pemberton wrote: > Hi, > Does anyone have any information on the drive capability of the MPLAB ICD2? Just one thought: how are you powering the ICD2? You know you can't use USB to power the ICD2 and then the ICD2 to power the target, you have to have an external supply to the ICD2 in the situation you have... Cheers, Howard Winter St.Albans, England

In message <@spam@200506052134.j55LYNin023012KILLspamfort-point-station.mit.edu>> "Howard Winter" <KILLspamHDRWKILLspamH2Org.demon.co.uk> wrote: > Just one thought: how are you powering the ICD2? You know you can't use > USB to power the ICD2 and then the > ICD2 to power the target, you have to have an external supply to the ICD2 > in the situation you have... I'm using a PC power supply to provide the +5V supply. The ICD and the PIC are all running from the same +5V supply. I think I've found the glitch - a bad solder joint on the crystal. I nudged the crystal and the joint failed - taking the pad and part of the track with it! An inch of Roadrunner wire seems to have fixed it - the bootloader is being detected now. I've still got to add some pullups to the RAM's OE and CE lines, and find out why the ABT245 bus buffers are killing the ICSP... Later. -- Phil. | Acorn Risc PC600 Mk3, SA202, 64MB, 6GB, RemoveMEphilpemTakeThisOuTphilpem.me.uk | ViewFinder, 10BaseT Ethernet, 2-slice, http://www.philpem.me.uk/ | 48xCD, ARCINv6c IDE, SCSI

Philip Pemberton wrote: > "Wouter van Ooijen" wrote: >> Where is your LVP (PGM pin) pull-down? > > I thought that was only required if you were using LVP... When you first program a PIC that supports LVP, LVP is enabled. If this pin is floating at that time, it could enable LVP. Considering that you disable this bit if you don't want LVP, this shouldn't be a problem on subsequent programming cycles, though. Gerhard

> > "Wouter van Ooijen" wrote: > >> Where is your LVP (PGM pin) pull-down? > > > > I thought that was only required if you were using LVP... > > When you first program a PIC that supports LVP, LVP is > enabled. If this pin > is floating at that time, it could enable LVP. Considering > that you disable > this bit if you don't want LVP, this shouldn't be a problem > on subsequent > programming cycles, though. I never fully understood the problem, but on some PICs (and maybe only for some silicon revisions) you must pull LVP down, even when using HVP, even when programming for a second time. I guess this has to do with the fact that when you erase the chip the LVP is (temporarily) enabled. Wouter van Ooijen -- ------------------------------------------- Van Ooijen Technische Informatica: http://www.voti.nl consultancy, development, PICmicro products docent Hogeschool van Utrecht: http://www.voti.nl/hvu

{Quote hidden}>-----Original Message----- >From: spamBeGonepiclist-bouncesspamBeGonemit.edu [TakeThisOuTpiclist-bouncesEraseMEspam_OUTmit.edu] >Sent: 06 June 2005 15:01 >To: 'Microcontroller discussion list - Public.' >Subject: RE: [PIC]: ICD2 drive capability > > >> > "Wouter van Ooijen" wrote: >> >> Where is your LVP (PGM pin) pull-down? >> > >> > I thought that was only required if you were using LVP... >> >> When you first program a PIC that supports LVP, LVP is >> enabled. If this pin >> is floating at that time, it could enable LVP. Considering >> that you disable >> this bit if you don't want LVP, this shouldn't be a problem >> on subsequent >> programming cycles, though. > >I never fully understood the problem, but on some PICs (and >maybe only for some silicon revisions) you must pull LVP down, >even when using HVP, even when programming for a second time. > >I guess this has to do with the fact that when you erase the >chip the LVP is (temporarily) enabled. That's exactly what causes the problem. The newer devices seem less prone to this issue, but the original 16F87x parts would give all sorts of odd and frustrating behaviour is PGM was left floating. 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. =======================================================================