16F877A HSERIN problem

[RFsolution]

Hi

I use codestudio and it has a build in terminal program

Still dont see where those pulses on the RX port com from

Even if I disconnect the MAX232 there are some pulses

I really think there is a config problem, I also asked the question to Mel
from Melabs

Any hints Welcome

I even checked versions of PBP to be sure there are no updates
i'm using 1.43

[Ioannis]

How fast is the string repeated?

After the labels TAR, ANT, AUX, EXT the values are ASCII or BINARY coming?

Ioannis

[DynamoBen]

I think everyone is looking past an important hint here. Those pulses on the uarts RX pin. Those pulses could be read as data accidentally and cause a problem. I've been there before.

If you disable the UART, do the pulses disappear? What types of signals are near by (pin wise)? The goal is to find out what if anything connected to the pic or in the code would be causing the pulses you speak of. There is a chance this is just general noise if that is the case it needs to be suppressed.

[RFsolution]

Hi Dymoben and other

No other signals nearby, it is generated by the PIC itself, clean negative going
pulses aproximatly 25 uSecondes long or 40khz

Walter

[DynamoBen]

Start tearing the code apart, there has got be de something doing it. In short you shouldn't have a pulse on an RX pin. Very odd.

[Dave]

RFsolution, The problem is in the "DEFINE HSER_CLOERR 1 ' automatic clear overrun error " statement. PBP clears the error by disabling the port and re-enabling it the same way as using the statement: RCSTA.4 = 0 and then RCSTA.4 = 1. this command set disables the receiver and then re-enables it to clear an overflow error. It's in the data sheet for the processor you are using. To prevent seeing this pulse you should set the output pin's state to normally high before using it as an input for the usart mode.

Dave Purola,
N8NTA

[RFsolution]

Thanks,

I will give it a try

I'm sure that those pulse are in conflict with the received data comming
from the max232

So if understand each time i use HSERIN i should make the pin high before

or just Tris portc.7 at startup ?