Strange problem with Serin/Serout on 16F628

[Atom058]

Bruce - Thanks for your elegant explanation - I now perfectly understand the difference between ST and TTL level inputs. Nicely stated!

And what you said about ST pins being used as xmit pins indicates that I should probably not have a problem doing that (I'm running at 5V, btw). Did you see any problem with my code as to why I don't seem to be transmitting to the player? Since I am not using a 232 chip, I am using the T9600 command (as opposed to the N9600 command). The Xmit and RCV pins (A.2 and A.3) are wired directly to the Xmit and RCV pins of the player. Should I be doing anything special with these connections? Like I said earlier, this works fine on my 628 board.

I appreciate your help. I am at wits end - it just doesn't make sense... Thanks!

[Bruce]

How do you know that you're not transmitting data to the player?

Have you looked at the tx output with a scope? Have you tried inverted mode?

Could be your player requires inverted serial. That would explain why it isn't responding.

Edit: You show @ DEVICE HS_OSC but you don't show any DEFINE OSC. If you're using
anything other than 4MHz, you'll want to define that oscillator speed. PBP assumes 4MHz
unless you specify otherwise, and that will for sure screw-the-pooch with timing if you're
not using a 4MHz osc. If you are using a 4MHz osc, you may want to switch to @ DEVICE
XT_OSC so you're not over-driving your 4MHz osc.

[Atom058]

Bruce - When it gets the valid command to play the sound clip, it plays. There is a status LED on the player that flashes when it gets the comand. It does not do that. I can take this player off the 877 board and can put it on the 628 board running the same code and it works fine. The only difference is that I am using A.3 and A.4 on the 877 for communication and B.6 and B.7 on the 628 board. Everything else is the same. That is what is so frustrating - it's like rotating your tires and now your car won't start. Rotate them back and everything works fine! Makes no sense!

Thanks again for all your help!

[Bruce]

Interesting problem. You seem to have everything configured OK for A/D & comparators off
with ADCON1 = 7 & CMCON = 7. Have you verified the PIC is even running by blinking an LED?

Edit: hold the phone. Your code indicates you're using A2 for TX and A3 for RX.

The only difference is that I am using A.3 and A.4 on the 877

If you're using A4 for TX, this pin is an open drain output. I.E. it can't go high!

[mackrackit]

Maybe, just maybe.
http://www.picbasic.co.uk/forum/showthread.php?t=562

I might be wrong But I do not think A.4 will work for tx.


edit
Better late than never, did not see the above post

[Bruce]

A4 can be used for an output, but it only goes high if you use an enternal pull-up resistor.

[Atom058]

Ya know - I really cringe when I have to finally break down and have to ask for help from you guys on the forum because when you figure out what my problem is, it is usually me doing something stupid (again). And this is the case once again. Bruce hit it on the head. I left out the "Define OSC 20" statement. I put this in and it now talks to the player just fine. I am using pins A.2 and A.3 (not A.4 - sorry about the typo). I even reverted back to using E.1 and E.2 and it still works just fine. It was that statement all along! Nothing to do with ST's (although I did learn something).

Thanks so much for your help! No telling how long it would have taken me to find that since I was not looking in the right place. Always helps to have a fresh pair(s) of eyes to look at stuff! Hopefully, someone will learn from this as well.

Thanks again!!!

[mackrackit]

Ya know - I really cringe when I have to finally break down and have to ask for help from you guys on the forum because when you figure out what my problem is, it is usually me doing something stupid (again).

We have all been there, and I bet I will be there again in an hour or two.
This is what the forum is for.