pin RDO (#20) of the pic 18F452 at ~4V

[dubphil]

Hello,

When my pic 18F452 is plugged on its socket and the SRIO test running, the J9:SI pin is less or equal to 4V.

When I check directly the #20 pin of the pic it is also less or equal to 4V. I've just tested a new pic provided by Mike, same results with older pics from SmashTV, any idea what can give this bad voltage on this pin ? I would like to make working my DIN and DOUT modules.

Best regards

Philippe

EDIT: sorry the title is wrong I mean the RD1 pin of the pic

Edited January 20, 2010 by dubphil

[lylehaze]

Hello,

When my pic 18F452 is plugged on its socket and the SRIO test running, the J9:SI pin is less or equal to 4V.

When I check directly the #20 pin of the pic it is also less or equal to 4V. I've just tested a new pic provided by Mike, same results with older pics from SmashTV, any idea what can give this bad voltage on this pin ? I would like to make working my DIN and DOUT modules.

Best regards

Philippe

EDIT: sorry the title is wrong I mean the RD1 pin of the pic

PIC pin 20, "RD1", should have a 10K pullup to +5 volts and a connection to J9, according to the schematics at UCapps.

Does the voltage read low when nothing is plugged in to J9?

[dubphil]

PIC pin 20, "RD1", should have a 10K pullup to +5 volts and a connection to J9, according to the schematics at UCapps.

Does the voltage read low when nothing is plugged in to J9?

If I understand well, I have of course tested the J9:SI voltage with nothing plugged in it.

if I test the voltage before the 10K R9 voltage is 5V, but if I test just after the voltage fall to less or equal to 4V

is this normal ?

Thanks for your kind help lylehaze.

Philippe

[dubphil]

if I test the voltage before the 10K R9 voltage is 5V, but if I test just after the voltage fall to less or equal to 4V

is this normal ?

As you have see, I'm not an electronician, but I recall this formula of the Ohm law : U = R*I

I use a generator of 9V/500mA that is regulated to 5V I don't know if the intensity is changed by the regulator.

Before the 10k resistor, I mesure a 5V voltage after the resistor I mesure less than 4V :

so 4 / 10000 = 0,0004 A (0.4mA) is this possible ?

suppose everything it's ok, the voltage directly after the resistor is 4V.

How can I would find 5V on J9:SI pin as suggest the SRIO interconnection test !!??

Philippe

[lylehaze]

As you have see, I'm not an electronician, but I recall this formula of the Ohm law : U = R*I

I use a generator of 9V/500mA that is regulated to 5V I don't know if the intensity is changed by the regulator.

Before the 10k resistor, I mesure a 5V voltage after the resistor I mesure less than 4V :

so 4 / 10000 = 0,0004 A (0.4mA) is this possible ?

suppose everything it's ok, the voltage directly after the resistor is 4V.

How can I would find 5V on J9:SI pin as suggest the SRIO interconnection test !!??

Philippe

Assuming that point X has a 10K pullup to +5 volts, and the voltage at point X reads 4 Volts, it would appear that you have resistance near 40K from point X to ground.

OR it may be that some digital signal is switching to ground at approx 25% duty cycle, and your meter is averaging the result.

Just two possibilities..

LyleHaze

[julienvoirin]

OR it may be that some digital signal is switching to ground at approx 25% duty cycle, and your meter is averaging the result.

c'est aussi mon opinion

Did you try a simple app like ain64_din128_dout128_v2c.zip ? when you connect SI to ground and release, it sends all the 128 midi note on/off messages

after that, connect the DIN to J9, and test each Input pin of serial registers (don't forget pull up 10K resistors).

when connected to ground it sends note On, note off when released. more over, note start from 0 and goes to 128 (if 4 DINx4 chained), indicating you which input of the 74HC165 could be dead (i had the problem 2 years ago)

[julienvoirin]

OR it may be that some digital signal is switching to ground at approx 25% duty cycle, and your meter is averaging the result.

c'est aussi mon opinion

Did you try a simple app like ain64_din128_dout128_v2c.zip ? when you connect SI to ground and release, it sends all the 128 midi note on/off messages

after that, connect the DIN to J9, and test each Input pin of serial registers (don't forget pull up 10K resistors).

when connected to ground it sends note On, note off when released. more over, note start from 0 and goes to 128 (if 4 DINx4 chained), indicating you which input of the 74HC165 could be dead (i had the problem 2 years ago)

[dubphil]

Did you try a simple app like ain64_din128_dout128_v2c.zip ? when you connect SI to ground and release, it sends all the 128 midi note on/off messages

At the edge of the suicide, I red back this post and I feel very bad to realize that I did not tested the app you've suggested to me, so today I did, and you know what ?

My CORE seems to perfectly work, if I connect J9:SI to ground all the events are sent :)

So I say loud and clear to the community : we are not expected to measure 5V at J9:SI, 3.8V seems to be sufficient for the PIC to send the events. Also there is A 20 KOhm resistance between J9:SI and VS and this doesn't seem to give any trouble ;)

This said, my buttons are by the way not working, so now I have to debug the DINX4 module, a step forward that's better than nothing.

Thanks a lot Julien !

Philippe

Edited February 21, 2010 by dubphil