SERIN & Timeout

I realize a projekt with a 868MHz-sender, which acts like a home-sign.

The sender acts OK, but the receiver makes me worry....

I don't use the internal Hardware-UART of the 16F872 (so far)...

I use the SERIN-command. It works ...

But if the sender is off, the receiver gets a lot of noise, so the Timeout of the SERIN-Command will not work, it restarts while it gets some high Input...

I have tried a lot of tricks, but it don't solve my problem (counting the impulses on the input takes to much of codespace, using a FOR-NET-Loop instead isn't better...)

The ISM-Connecting works fine (10 Bytes $55 or so to sync and 1 Start-byte $96 and 4 Bytes ($A5 or so) to carry 8 bit of information ... I am a lousy pragmatiker)

But the timeout in the SERIN (and more in the SERIN2) -Command makes me worry....

At the weekend I begin to change the librarys of PBP !



BTW: Accessing X[1] or so with the SERIN / SEROUT-command will not work, it seems to be fouly....

But if the sender is off, the receiver gets a lot of noise, so the Timeout of the SERIN-Command will not work, it restarts while it gets some high Input...


Try tying your receiver pin to ground, to force a ground. thus hopefully getting rid of the "noise". your Serin is reacting to Noise. And you need to rid yourself of this noise.

Dwayne

Try to use the internal USART, you must use HSERIN instead of SERIN. If you want to be sure to not overflow the input buffer add

DEFINE HSER_CLROERR 1

at the begining of your program.


For the noise... have you any pull down/Pull up resistor on the RX pin of your PIC. Do you use MAX232 ???

"At the weekend I begin to change the librarys of PBP !"
Must be sure that's the problem before...!!! I'm pretty curious to see your code and schematics before.

Hello,

the noise is coming out of the ISM-receiver, because of the free floating of the filters...
It can't be turned off with a resistor!

Because our local dealer has no PICs, I must look at the sources in the librarys.... Uuups.

I has managed the problem....

Throw away these timeout-feature of the PBP!
Use handcoded programs !

;-)

Using Timer1 as a Timer (475ms) and the stupid SERIN-Command to look into the stream of pulses out of the receivers...
If there is a byte (and the SERIN will receive MANY! ... they ignore the stopbit and don't check the framing....) check it and if it is our startbyte, get the next 4 bytes.
Putting this in a loop until the Timer is done...


;Timer1 setzen
;Teiler /8 OSC/4 als Input = 125kHz
T1CON.5=1
T1CON.4=1
;0,475 Sekunden = -59375 = 1811h
TMR1H=$18
TMR1L=$11
;INT-Flag löschen
PIR1.0=0
;GO!
T1CON.0=1
;Flag für Müll-Empfang setzen
Dummy_Bit=1
;Funkmodul auslesen
REPEAT
SERIN Funk_IN,T2400,Dummy
IF Dummy=$96 THEN
SERIN Funk_IN,T2400,Buf_Sin[0],Buf_Sin[1],Buf_Sin[2],Buf_Sin[3]
;merken, daß ein Empfang stattfand
Dummy_Bit=0
ENDIF
;Zeit ablaufen lassen
UNTIL PIR1.0
;Timer stoppen
T1CON.0=0
;empfangene Zeichen auf Byte umrechnen
Dummy=Buf_Sin[0]:GOSUB Manch2Bit
Dummy=Buf_Sin[1]:GOSUB Manch2Bit
Dummy=Buf_Sin[2]:GOSUB Manch2Bit
Dummy=Buf_Sin[3]:GOSUB Manch2Bit