Strange SerOut Problem

[masosi]

Would it be worth trying a 350W Computer PSU?
Are it's outputs (5VDC & 12VDC) regulated?

[skimask]

Would it be worth trying a 350W Computer PSU?
Are it's outputs (5VDC & 12VDC) regulated?

More trouble than it's worth. Get a NiMH battery pack and a charger. Smaller, more controllable, etc. And those computer PSU's DO require a minimum load and you have to do some trickery to them to get them to work.

[masosi]

More trouble than it's worth. Get a NiMH battery pack and a charger. Smaller, more controllable, etc. And those computer PSU's DO require a minimum load and you have to do some trickery to them to get them to work.

Ok, thanks again.


I can see a LED flash on PORTA.1 and now PORTB.5 when it does SerOut, so I guess the ports are fine.
So if its not timing, not the programming, not the chip, not the COM port and not Hyperterminal - I DON'T KNOW WHAT TO DO!!!

[paul borgmeier]

1) Are you sure you have pin 2 correct and pin 5 correct (you are using a 9 pin connector that is straight thru?) see http://www.airborn.com.au/rs232.html

2) Try it without TX connected

3) A must - add a decoupling capacitor across VDD and VSS (10 uF should do or anything close to this)

4) You do have pin 5 connected to your PIC ground?

5) try another power supply that can be regulated (or 3 AA batteries in series)

6) Do you have access to an oscilloscope? see what is coming out of PortA.1 and pin 2 on the cable?

7) Check your hyperterminal settings to make sure you have 300 selected and the parity off

8) you have been using a crystal like in your sketch?

report back

[masosi]

1) Are you sure you have pin 2 correct and pin 5 correct (you are using a 9 pin connector that is straight thru?) see http://www.airborn.com.au/rs232.html

Correct

2) Try it without TX connected

Will do again - didn't make a difference last time

3) A must - add a decoupling capacitor across VDD and VSS (10 uF should do or anything close to this)

Will do

4) You do have pin 5 connected to your PIC ground?

Yes

5) try another power supply that can be regulated (or 3 AA batteries in series)

Will do

6) Do you have access to an oscilloscope? see what is coming out of PortA.1 and pin 2 on the cable?

I don't have one unfortunately - an LED flashes like mad though...

7) Check your hyperterminal settings to make sure you have 300 selected and the parity off

Have checked that many times!

8) you have been using a crystal like in your sketch?

4MHz with capacitors as drawn

[masosi]

My computer won't talk to a serial modem anymore... and it won't echo its own data from Tx to Rx either...
That explains it!

Then a new question pops up... How was the serial JDM2 programmer verifying the PIC's contents? (I know the PIC was being programmed successfully too!)

Anyway, I'll get my hands on a new set of serial ports tomorrow

Skimask and Paul, thankyou so much for your help so far! I've learnt alot even though the ideas havn't solved my problem! Thanks again!

[mackrackit]

In post 5 I asked about the PC port, and you said that the same thing happened on another computer. ?????

As far as the programmer software reading back correctly, all I can say is it happens. I have a PICKIT1 that will read back errors if I use the software that microchip supplied, but mplab does not. Both software work. I would guess in this case the "lesser" software does not have something correct in its receiving side, like a checksum miss calc.

Again, check the signal with a meter. TX will show low (Maybe even a negative value) when idle and will spike anywhere from 2.5 to 25 V+ at transmit. If you have a machine less than 10 years old or using a usb/serial adpt, you will most likely see 2.5 to maybe 6.