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Discussion Groups | Piclist | Real Low Power Reading Flash Memory
A discussion group for the PICMicro microcontroller. Also called the Microchip PIC, this list is dedicated to the use and abuse of this fine, simple, microcontroller. Close to topic posts are welcome, ie. general electronics.
Real Low Power Reading Flash Memory - rj_satterlee - Apr 3 10:48:30 2006
Hi all-
I had an interesting experience this weekend (yes, it was on April
1st). But this is a real true story.
I'm working on a low voltage pic programmer and I'm in the process of
debugging it.
I had my laptop parallel port connected to the pic with the usual
culprits, ~MCLR, PRG, PRD, PRC, and a little NPN transistor to take
care of the bidirectional nature of the PIC data pin (input data
goes to a parallel port status line rather than try to turn the
port around). Pretty typical stuff.
O.K. so I was dinking around with the program and reading the lower
portions of the flash memory. Things weren't working, so I was
fiddling with stuff. Then I could start reading the flash. Cool.
Then I noticed that I had disconnected power to the board!
I was reading the flash from the power generated from the ~MCLR and
PGM signals feeding back to the power plane of the PIC dice! There
was enough power to read the flash from the leakage (or rather
forward biased) signal lines. This followed through (I guess)
out the VDD pin to the collector resistor on the NPN!
Of course, when I put a low impedance across the power pins, the
thing stopped working (aligator clips from the power supply to
the pic protoboard).
Still it DID have to happen on April 1st.
Thought the group might get a chuckle out of this. Needless to
say, I was one puzzled engineer for awhile.
Cheers,
Rich S.
to unsubscribe, go to http://www.yahoogroups.com and follow the instructions
Yahoo! Groups Links
(You need to be a member of piclist -- send a blank email to piclist-subscribe@yahoogroups.com )
I had an interesting experience this weekend (yes, it was on April
1st). But this is a real true story.
I'm working on a low voltage pic programmer and I'm in the process of
debugging it.
I had my laptop parallel port connected to the pic with the usual
culprits, ~MCLR, PRG, PRD, PRC, and a little NPN transistor to take
care of the bidirectional nature of the PIC data pin (input data
goes to a parallel port status line rather than try to turn the
port around). Pretty typical stuff.
O.K. so I was dinking around with the program and reading the lower
portions of the flash memory. Things weren't working, so I was
fiddling with stuff. Then I could start reading the flash. Cool.
Then I noticed that I had disconnected power to the board!
I was reading the flash from the power generated from the ~MCLR and
PGM signals feeding back to the power plane of the PIC dice! There
was enough power to read the flash from the leakage (or rather
forward biased) signal lines. This followed through (I guess)
out the VDD pin to the collector resistor on the NPN!
Of course, when I put a low impedance across the power pins, the
thing stopped working (aligator clips from the power supply to
the pic protoboard).
Still it DID have to happen on April 1st.
Thought the group might get a chuckle out of this. Needless to
say, I was one puzzled engineer for awhile.
Cheers,
Rich S.
to unsubscribe, go to http://www.yahoogroups.com and follow the instructions
Yahoo! Groups Links
(You need to be a member of piclist -- send a blank email to piclist-subscribe@yahoogroups.com )