non-inverting 2400 baud

[cooksydesign]

Sorry about that. I left out some important information. I am using a 16F628A, it does not have a USART so I am unable to use HSER function. Thanks for the suggestion though. I am also using the WAIT parameter. I am expecting to see a hex value between 31 and 39 but I am receiving fe. Not sure what fe is, but it is consistant.
Again, thanks for any suggestions.

b

[Archangel]

Sorry about that. I left out some important information. I am using a 16F628A, it does not have a USART so I am unable to use HSER function.

Don't know where you got those, BUT the 16F628A chips I use has USART pin7 RX, pin 8 TX.

[cooksydesign]

You are correct, I clicked on the wrong link when I was looking at dataseets yesterday. As I mentioned earlier, the circuit was working for quite awhile so I made a few boards. Now I see there are some problems with a few other PC's. Back to my original question, if 16780 works for 2400 baud in a SER2 command, what is the True seeting? I tried 396, then I get something other than what I expect. Looks like a baud rate setting. I can remove the MAX8130 and the circuit works fine, when the SER2 commands are returned to the proper settings. Thanks for pointing out the USART pins. Unfortunately, I have made boards and those pins are used.

b

[Archangel]

You are correct, I clicked on the wrong link when I was looking at dataseets yesterday. As I mentioned earlier, the circuit was working for quite awhile so I made a few boards. Now I see there are some problems with a few other PC's. Back to my original question, if 16780 works for 2400 baud in a SER2 command, what is the True seeting? I tried 396, then I get something other than what I expect. Looks like a baud rate setting. I can remove the MAX8130 and the circuit works fine, when the SER2 commands are returned to the proper settings. Thanks for pointing out the USART pins. Unfortunately, I have made boards and those pins are used.

b

In the back of the Book, Appendix A

B/R    OUTPUT  CONVERSION  PARITY      MODE 
2400   DRIVEN  TRUE           NONE      396
2400   DRIVEN  TRUE           EVEN     8588
2400   DRIVEN  INVERTED       NONE    16780
2400   DRIVEN  INVERTED       EVEN    24972
2400   OPEN    TRUE           NONE    33164
2400   OPEN    TRUE           EVEN    41356
2400   OPEN    INVERTED       NONE    49548
2400   OPEN    INVERTED       EVEN    57740

[mister_e]

What I suggest is to set the TX pin to the normal idle State at the top of your program and add a pause of few mSec. True mode idle high, while inverted idle low.

[cooksydesign]

I changed the baud rate setting from 396 to T2400 and the correct data was sent out. What's the difference between 396 and T2400? I don't know. Something similar to this happened before and I ended up using N2400 when a line driver is not used. I didn't see a reference to T2400 in the book.

Is there a way to clear the output buffer in the PIC 16F628a? The PIC sends a D0 first time, every time. Nowhere in the program do I load a D0. When I send the proper data twice, the receiving program discards the D0 and recognizes the correct data and accepts that. Strange.

Thanks for all suggestions earlier.

B

[mister_e]

You need to set the idle level first at the top of your program, then send your data.

For true mode, your serial output must be set high, for inverted, it's low.

T2400, N2400 are for SEROUT, all other numbers 396,16780 are for SEROUT2