On 14 Mar 2004 at 4:27, Anthony Van Herrewege wrote:
> Ok, I think I uninstalled the WinXP/NT driver
> yesterday. I installed it again, but when I choose
> Direct I/O I don't get any signal on the COM port.
> Delay is 1 mS. New measurements:
>
> Ground reference is pin #12/31.
> x -> y means that the measurement is first x then
> starts going up/down until it reaches y.
>
> MCLR (pin #1): 9.75V -> 8.68V (1-2 mins later) - Off:
> -0.5V - Should be: 14V
> Vcc (pin #11): I measured about everything below 1V
> (starting at 0.95V and then it keeps getting lower) -
> Off: 0.2V lower than On - Should be: 5V
> Clock (pin #39): 15.7V/12V - Off: 0.2V -> -0.2V -
> Should be: 5V +- 1V
> Data Out (pin #40): 0.4V -> 0.15V (2 mins later) -
> Off: -6V - Should be: 5V +- 0.5V
>
> I'm getting so frustrated.
> If anyone comes up with a solution or something,
> please tell me :).

I would suggest tracing things through in some kind of logical sequence.

Run ICProg, hook up your serial cable to your COM port, with the JDM
disconnected. Go to Settings>Hardware Check and toggle the enable signals
one by one, check each with a multimeter that they are toggling the
appropriate COM port signals at the end of your cable. This will make sure
you don't have any software/operating system/setup problems. Enable Vcc is
not supported with my JDM design.

When that is tested OK plug in your JDM and then see what toggling each
signal does as above. It should then just be a matter of hardware fault
finding. Problems I would look for would be diodes in the wrong place or
inserted the wrong way around, transistor pin-out wrong, short circuit etc.

My working JDM on Win XP, NT/2000 driver enabled, Direct I/O, I/O delay =
5, no chip inserted, gives the following readings measured relative to VSS:

VDD = 5.3V (cannot be toggled)
MCLR = 13.6V (-0.7V off)
CLK = 6V (-0.7V off)
DAT = 4.9V (-2.2V off)

Don't give up yet!

--
Brent Brown, Electronic Design Solutions
16 English Street, Hamilton, New Zealand
Ph/fax: +64 7 849 0069
Mobile/txt: 025 334 069
eMail:  brent.brown@clear.net.nz

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