No Data out of RCREG

[grayfuse]

Hello list, I'm new to the forums, but they have been very helpful!

Perhaps someone can help me with this snag... I'm using Hardware Serial Interrupts on a 18F452 reading in midi data. From the LED I have in the interrupt, I can tell the interrupt is operational, and I know that I'm reading the RCREG register because it clears the RCIF flag allowing main loop to run again.

Even though these two things are happening, the RCREG variable I'm putting into inByte is showing up as an empty value. Does anyone know why this could be happening? Code is below...



DEFINE OSC 20
DEFINE HSER_BAUD 31250

On Interrupt Goto myint ' Define interrupt handler (PBP Gimme)

RCSTA = $90 'didnt want to look up the binary for these ;)
TXSTA = $24
INTCON = %11000000 ' Enable peripheral interrupts
PIE1.5 = 1 ' Enable Serial Interrupt

loop:

LOW led
'main loop
Goto loop

' INTERRUPT HANDLER
Disable ' PBP Command - No interrupting past this point
myint: ' If we get here, an interrupt has been thrown
INTCON = 0 ' clear INTCON (maybe redundant)

if PIR1.5 = 1 THEN ' If Serial Interrupt (for mult interrupts)
HIGH led
inByte = RCREG ' if this clears RCREG, then this will also
' reset the PIR1.5 flag, therefore allowing
' main loop to run again
ENDIF
INTCON = %11000000 ' Clear external interrupt flag

Resume ' Glorified PBP "Return" to main program
Enable

[mister_e]

first thing i notice, as you don't use any HSERIN/HSEROUT, i doubt the HSER_BAUD will do something for you so what about if you remove it and use
SPBRG=39?

next one have a look to the following link. It could be handy.
http://www.picbasic.co.uk/forum/showpost.php?p=8601&postcount=11

AND the following could be interesting too.. i just can't remind where i have posted it here. BTW have fun


'
' Simple program to handle USART interrupt using PIC16F877 @20MHZ
' ================================================== =============
'
' This program will Blink a LED on PORTB.0 to show
' that the PIC is running.
'
' This program also allow the user to activate or deactivate
' a LED connected on PORTB.1 pin by sending command from a PC
' terminal software using 9600,n,8,1 setting
'
' User command:
' =============
' 1. If character "1" is received => enable the LED
' 2. if character "2" is received => disable the LED
'
'
DEFINE LOADER_USED 1 ' using bootloader
DEFINE OSC 20 ' running at 20 MHZ

' PORT setting
' ============
'
TRISC=%10000000 ' RC.7 => USART RX pin set to input
' all other pin set to output
'
TRISB=0 ' RB<7:0> set to output

' USART setting
' =============
' Since we will not use HSERIN/HSEROUT, we must
' write directly to internal PIC register
'
TXSTA=$24 ' enable transmit and SPBRGH=1
RCSTA=$90 ' Enable USART and continuous receive
SPBRG=129 ' BAUD RATE = 9600 BAUDS

' Interrupt definition
' ====================
'
PIE1.5 =1 ' enable USART receive interrupt
INTCON.6 =1 ' enable peripheral interrupt

' Alias definition
' ================
'
RCIF var PIR1.5 ' receiver interrupt
StatusLED var PORTB.0 ' the LED who show a 'running process'
UserLED var PORTB.1 ' the LED that user want to control

' Variable definition
' ===================
'
Delay var word '
DataIn var byte ' use to store RCREG content
Discard var byte ' use to erase RCREG register

' Hardware/software initialisation
' ================================
'
PORTB=0 ' clear PORTB
on interrupt goto USARTInterrupt

Start:
' Main program loop that make the user happy to
' see a LED flashing to mean that something is
' running
'
toggle statusled
for delay = 1 to 5000 ' use a loop delay to ensure
pauseus 5 ' getting interrupt as fast as
next ' possible
goto start


disable interrupt
USARTInterrupt:
' Here's the interrupt routine who will make the user
' much happy by giving him the feeling to have the
' control on the machine when the status of the user
' LED will change
'
RCSTA=0 ' Disable serial port AND
' clear possible error (FERR,OERR)

datain=RCREG ' Get data

while RCif ' wait untill the RCREG is empty
discard=RCREG ' by reading it and store result in a
wend ' don't care variable

select case datain ' What to do with that data???

case "1" ' User selection = 1
userled=1 ' => Enable the LED

case "2" ' User selection =2
userled=0 ' => disable the LED

end select
RCSTA=$90 ' Re-enable the serial PORT AND
resume ' get out of here
enable interrupt

So in your code yes you can receive something... is this a valid data? i don't think so. You can even have an interrupt by sending an audio signal or else to your USART. So BaudRate is the main problem... i guess or you don't use any RS-232 inverter like MAX232

[grayfuse]

That was the problem, thanks a lot! Never took into account the Define was a PBP define that wasn't doing specifically what I needed.

Thanks again!

[mister_e]

PBP define will work only if you use HSERIN/HSEROUT. While you don't use them but interrupt, they'll not be considered.

Thanks to Bruce for this precious discover many times ago !