Serin loop of death

C

cybersky

Member

• Sep 5, 2011

• #1

Hi All

I have been building small pic networks using the rs232 interface, hardware (16f874) or software version (16f84). PROBLEM. If you use serin it will wait for the amount of bytes specified, forever. IS there a timeout available ?

 

Ian Rogers

User Extraordinaire

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Most Helpful Member

• Sep 5, 2011

• #2

No... I don't think there's a work round either

 

ericgibbs

Well-Known Member

Most Helpful Member

• Sep 5, 2011

• #3

cybersky said:

Hi All

I have been building small pic networks using the rs232 interface, hardware (16f874) or software version (16f84). PROBLEM. If you use serin it will wait for the amount of bytes specified, forever. IS there a timeout available ?

Click to expand...

You could consider using a timer interrupt, start it when you use the Serin command.

 

P

Pommie

Well-Known Member

Most Helpful Member

• Sep 5, 2011

• #4

Write you own routine. I assume you can check the RXIF bit.

Mike.

 

C

cybersky

Member

• Sep 5, 2011

• #5

so if i use the timer i could just chk for predefined timeout value then simply goto next code block? rxif is that for software or hardware only ? so if rxif bit is xx goto chkdata something to that effect ?

 

P

Pommie

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Most Helpful Member

• Sep 5, 2011

• #6

The bit PIR1.RXIF gets set when a byte is received. The received byte is in RCREG, reading this register clears RXIF. This is for hardware only.

Edit, how do you check a timer in a continuous loop?

Mike.

 

Last edited: Sep 5, 2011

Ian Rogers

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• Sep 5, 2011

• #7

Pommie... Its a software rx tx so no interrupts or flags... The best thing is what Eric said Start a timer interrupt, if it times out stop the serin.

 

P

Pommie

Well-Known Member

Most Helpful Member

• Sep 5, 2011

• #8

The OP mentioned both hardware and software. However, even software serial can be written to mimic hardware by using interrupts.

And, to repeat myself, how do you check for a timer timeout in a library routine? Plus, how do you stop a library routine from an interrupt?

Mike.

 

Ian Rogers

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• Sep 5, 2011

• #9

See what you mean.....Duh!!!..... sorry....shutting up now.

 

languer

Active Member

• Sep 11, 2011

• #10

an example for 16F84 shown below

Code:

Define CONF_WORD = 0x3ff2

Dim x As Bit
Dim y As Byte

init:
AllDigital
x = 1

main:
Serout RB0, 9600, "Hello world!", CrLf
While x = 1
		Call serin_timeout(100)
Wend
End                                               
Proc serin_timeout(t As Byte)
	Dim serin_flag As Bit
	serin_flag = 0
	'enable prescaler for tmr0
	OPTION.PSA = 0
	'set tmr0 prescaler for 8
	OPTION.PS2 = 0
	OPTION.PS1 = 1
	OPTION.PS0 = 0
	'enable tmr0
	OPTION.T0CS = 0
	'clear tmr0
	TMR0 = 0
	While TMR0 < t
		If PORTB.1 = 0 Then
			Serin RB1, 9600, y
			Serout RB0, 9600, y, CrLf
			serin_flag = 1
		Endif
	Wend
	If serin_flag = 0 Then
		Serout RB0, 9600, "TIMEOUT", CrLf
	Endif
	'clear tmr0
	TMR0 = 0
	'disable TMR0
	OPTION.T0CS = 1
End Proc

 

C

cybersky

Member

• Sep 16, 2011

• #11

hi all - thanks for the replies. too busy at work to even chk email let alone my fav forum. I will try code languer and give feedback asap. Thanks again

 

alec_t

Well-Known Member

Most Helpful Member

• Sep 16, 2011

• #12

If you use serin it will wait for the amount of bytes specified, forever. IS there a timeout available ?

Click to expand...

Can't you use the WDT?