gnupic: Re: [gnupic] first attempt flops
Subject:
Re: [gnupic] first attempt flops
From:
Robert Pearce ####@####.####
Date:
15 Jun 2006 09:24:15 +0100
Message-Id: <AXulPWC$jRkEFw6a@jonah.huneausware.local>
On Wed, 14 Jun 2006, Maxim Wexler ####@####.#### wrote :
>
>Device pic16f874, program memory: 4096, data memory: 128.
>CPU clock speed: 930 MHz
>Burning program memory,/dev/ttyS0:PIC programmer missing or chip fault
>/dev/ttyS0:0000:unable to read pic while programming
>
>The chip is brand new from Digi-key, never been programmed before. I know
>the port is OK cuz I've used it with an external modem, minicom works and I
>can scope the TxD line when I send keyboard input through the port.
>
>Anybody see what's wrong here?
It's pretty hard to say without some digging around. I haven't used that
programmer (I designed my own, parallel port one) nor that software
(though it was one of the options I looked at before crafting my own).
But that sort of error is reminiscent of behaviour I have experienced
due to any one of the following:
- programmer not powered
- programmer not connected / plugged into wrong port
- chip not connected to programmer
- chip in circuit with too much load on the RB6/7 pins
- chip in circuit with Vpp wired wrongly
- chip enters LVP mode erroneously (RB3 floating)
- Connections to RB6/7 swapped
- Vpp applied before Vdd (or vice-versa on 16F628)
The last one is a programmer software configuration error, so I'd hope
that's not it, but it can't be entirely ruled out if the author hasn't
explicitly tested your particular combination of programmer and PIC. It
certainly caught me the first time I tried to program a 16F871, having
previously managed to get it working on a 16F628.
If you have access to a 'scope (ideally a fancy 8 channel storage scope,
but any will do) then look at what's happening on the Vdd, Vpp, RB6 and
RB7 pins. Then compare that to what the Microchip ICSP guide says should
happen.
--
Rob Pearce http://www.bdt-home.demon.co.uk
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