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Discussion Groups | Piclist | Re: PIC universal programmer - spec and design

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.

Re: PIC universal programmer - spec and design - Igor Janjatovic - Apr 9 12:52:00 2004

Hello,

What about "TAIT Classic" programmer!?

It has external power supply, regulated 13V and 5V, buffered digital signals
with 7407, proper rise and fall times and it's using parallel port. It is
supported by ICProg, which means that most of currently available PIC
devices can be programmed using this ICSP programmer.

Anyone using TAIT programmer? I have schematic and it seems that 4k7 and 10k
resistors on 7407d and 7407c parts should be swapped! First, there should be
10k pull-up on 7407 and then 4k7 to the base of transistor! Any experience
with this issue? It seems to me that in some situations this circuit might
not work!? Everything else is perfect as I already said...

Regards,
Igor

P.S.
I managed to find JDM schematic (most popular) and to make one on my proto
board. I performed few tests using digital o'scope and here are the results:

GND line from RS232 is actually used as +5V power supply for PIC. In order
to have that, both TXD and RTS are kept low at the beginning (minus voltage
in respect to GND).

When programming starts, TXD goes high and it activates Vpp on PIC through
T1. Then, RTS is used for clock. DTR performs Data_Out function and CTS is
used as Data_In.

Rise and fall times of Vpp are approx. 600ns which is just fine. Rise and
fall times of clock and data are approx. 500ns which is also OK.

+5V is always present on the device, which is bad solution if you ask me. It
seems impossible to shutdown +5V according to JDM schematic.



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