How On Interrupt works?

[Bruce]

http://www.microengineeringlabs.com/...bp/serbufx.bas

[sayzer]

http://www.picbasic.co.uk/forum/ could also be helpful.


____________

[koossa]

Bruce, thank you very much for your sample file.
I have tried to create an easier implementation, just to see if it is working on my circuit.
I have a TX circuit and an RX circuit, using RS485.

Below is my code. The LED on the TX is blinking, but not on the RX side.
Any idea what I am doing wrong?

<b>TX Code</b>
<hr>
<code>
&nbsp;&nbsp;Include "Modedefs.bas"

&nbsp;&nbsp;DEFINE&nbsp;&nbsp;&nbsp;&nbsp; OSC 4

&nbsp;&nbsp;DE_OR_RE&nbsp;&nbsp;&nbsp;&nbsp;VAR PORTC.5&nbsp;&nbsp;&nbsp;&nbsp; ' DE and RE Pin of SN75176
&nbsp;&nbsp;LEDPIN&nbsp;&nbsp;&nbsp;&nbsp; VAR PORTD.2&nbsp;&nbsp;&nbsp;&nbsp; ' LED to confirm PIC is running
&nbsp;&nbsp;DATARECEIVED&nbsp;&nbsp;VAR BYTE
&nbsp;&nbsp;
&nbsp;&nbsp;'======== HSEROUT, HSERIN SETTINGS ==========
&nbsp;&nbsp;DEFINE HSER_RCSTA 90h
&nbsp;&nbsp;DEFINE HSER_TXSTA 24h
&nbsp;&nbsp;DEFINE HSER_BAUD 9600

&nbsp;&nbsp;ADCON1 = 7

&nbsp;&nbsp;RCIF&nbsp;&nbsp;VAR&nbsp;&nbsp;PIR1.5& nbsp;&nbsp;&nbsp;&nbsp;' Alias RCIF (USART Receive Interrupt Flag)
&nbsp;&nbsp;OERR&nbsp;&nbsp;VAR&nbsp;&nbsp;RCSTA.1 &nbsp;&nbsp;&nbsp;&nbsp;' Alias OERR (USART Overrun Error Flag)
&nbsp;&nbsp;CREN&nbsp;&nbsp;VAR&nbsp;&nbsp;RCSTA.4 &nbsp;&nbsp;&nbsp;&nbsp;' Alias CREN (USART Continuous Receive Enable)
&nbsp;&nbsp;
Main:
&nbsp;&nbsp;HIGH DE_OR_RE&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp; ' Make ready for RX
&nbsp;&nbsp;HSEROUT ["1"]&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&n bsp;&nbsp;&nbsp;&nbsp; ' Send R1
&nbsp;&nbsp;HIGH LEDPIN
&nbsp;&nbsp;PAUSE 5000
&nbsp;&nbsp;LOW LEDPIN
&nbsp;&nbsp;PAUSE 5000
GOTO MAIN

END
</code>


<b>RX Code</b>
<hr>
<code>
&nbsp;&nbsp;Include "Modedefs.bas"
&nbsp;&nbsp;&nbsp;&nbsp;
&nbsp;&nbsp;DEFINE&nbsp;&nbsp;&nbsp;&nbsp; OSC 4

&nbsp;&nbsp;DE_OR_RE&nbsp;&nbsp;&nbsp;&nbsp;VAR PORTC.5&nbsp;&nbsp;&nbsp;&nbsp; ' DE and RE Pin of SN75176 (RS485)
&nbsp;&nbsp;LEDPIN&nbsp;&nbsp;&nbsp;&nbsp; VAR PORTD.2&nbsp;&nbsp;&nbsp;&nbsp; ' LED Pin
&nbsp;&nbsp;i&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbs p; VAR BYTE

&nbsp;&nbsp;'======== HSEROUT, HSERIN SETTINGS ==========&nbsp;&nbsp;
&nbsp;&nbsp;DEFINE HSER_RCSTA 90h
&nbsp;&nbsp;DEFINE HSER_TXSTA 24h
&nbsp;&nbsp;DEFINE HSER_BAUD 9600

&nbsp;&nbsp;ADCON1 = 7

&nbsp;&nbsp;RCIF&nbsp;&nbsp;VAR&nbsp;&nbsp;PIR1.5& nbsp;&nbsp;&nbsp;&nbsp;' Alias RCIF (USART Receive Interrupt Flag)
&nbsp;&nbsp;OERR&nbsp;&nbsp;VAR&nbsp;&nbsp;RCSTA.1 &nbsp;&nbsp;&nbsp;&nbsp;' Alias OERR (USART Overrun Error Flag)
&nbsp;&nbsp;CREN&nbsp;&nbsp;VAR&nbsp;&nbsp;RCSTA.4 &nbsp;&nbsp;&nbsp;&nbsp;' Alias CREN (USART Continuous Receive Enable)

&nbsp;&nbsp;LOW DE_OR_RE&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&n bsp;&nbsp;&nbsp;' Make ready for RX
&nbsp;&nbsp;INTCON = %11000000&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp ;&nbsp;&nbsp;&nbsp;' Enable interrupts
&nbsp;&nbsp;ON INTERRUPT GoTo serialin&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;' Declare interrupt handler routine
&nbsp;&nbsp;PIE1.5 = 1&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;& nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;' Enable interrupt on USART

DoSomeStuff:
&nbsp;&nbsp;For i = 0 to 10
&nbsp;&nbsp;&nbsp;&nbsp;Pause 2
&nbsp;&nbsp;Next i
&nbsp;&nbsp;GOTO DoSomeStuff
&nbsp;&nbsp;
serialin:&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp ;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;& nbsp;' Buffer the character received
&nbsp;&nbsp;GOSUB BLINK
&nbsp;&nbsp;RESUME
&nbsp;&nbsp;
BLINK:
&nbsp;&nbsp;HIGH LEDPIN
&nbsp;&nbsp;PAUSE 1000
&nbsp;&nbsp;LOW LEDPIN
&nbsp;&nbsp;PAUSE 1000
&nbsp;&nbsp;RESUME

END

</code>

[Bruce]

Lookup disable in your manual under ON INTERRUPT. Then lookup RETURN under GOSUB. That will get you started.

[koossa]

Thank you!!

[Bruce]

You're welcome, but you'll want to consider a few other things here too.

1. RCIF is only cleared after a read of RCREG. To clear RCIF, you will want to read this data
with HSERIN or X = RCREG until RCIF is cleared.

2. Values you use in hardware USART defines are not loaded into USART registers if there is
not at least one instance of HSERIN or HSEROUT used somewhere within your program.

Just inserting these defines is not configuring the hardware USART for you. Just FYI.

[Archangel]

You're welcome, but you'll want to consider a few other things here too.

1. RCIF is only cleared after a read of RCREG. To clear RCIF, you will want to read this data
with HSERIN or X = RCREG until RCIF is cleared.

2. Values you use in hardware USART defines are not loaded into USART registers if there is
not at least one instance of HSERIN or HSEROUT used somewhere within your program.

Just inserting these defines is not configuring the hardware USART for you. Just FYI.

Hi Bruce,
That's good info! Thanks, How is that book coming? Sign me up for a copy
JS