HSERIN using EUSART RX interrupt - how does it really work?

[flotulopex]

Thank you Richard,

Actually, my program works on a 8MHz basis - it should be more than enough to handle 9600bps serial data, no?

I'd like to stick to the very basics since I'm not an ultra-programming-geek (just a curious guy). I often heard and read about DT's interrupts but it looks "too much" to me, a least, for my so small projects.

HSerin [STR SData\5]
puts your 690 in a blocking loop until 5 characters have been received, no matter how long it takes its not isr material

Thanks a lot for explaining this.


As far as I read the DS, the RX buffer can store 2 characters. Starting this thread, my example was using a 5 characters but in fact, I will always have unknown data length (I'll read sms messages) - so let's forget the 5 characters story

Since you refer to it, why is there a buffer of "2" characters? What's its use?


This is my latest code I modified to receive 1 character at the time giving the chance of handling variable lenght incoming data:

' ====== FUSES ====================================================================================
' PIC 16F690 Fuses (MPASM)
@ __config _FCMEN_OFF &_IESO_OFF &_CPD_OFF &_WDT_OFF &_INTRC_OSC_NOCLKOUT &_BOR_OFF &_CP_OFF &_PWRTE_OFF &_MCLRE_OFF
@ ERRORLEVEL -306

' ====== REGISTERS =================================================================================
OSCCON     = %01110000 'Internal RC set to 8Mhz - Register not to be used with XTal
OPTION_REG = %10000000 'PORT A&B Pull-Ups (look WPUA & WPUB)
ADCON0     = %00000000 'A/D Module
ANSEL      = %00000000 'Select analog inputs Channels 0 to 7
ANSELH     = %00000000 'Select analog inputs Channels 8 to 11
INTCON     = %11000000 'INTERRUPT Control
PIE1       = %00100000 'Peripheral Interrupts

' ====== UART SETTINGS ============================================================================
RCSTA      = %10010000 ' Enable serial port & continuous receive
TXSTA      = %00100000 ' Enable transmit, BRGH = 0
SPBRG      = 12        ' 9600 Baud @ 8MHz, 0.16%

' ====== DEFINES ==================================================================================
DEFINE OSC 8
DEFINE NO_CLRWDT 1   ' Don't waste cycles clearing WDT  
DEFINE HSER_CLOERR 1 ' Automatic clear overrun error 

' ====== VARIABLES ================================================================================
LED     VAR PORTB.6
SData   VAR BYTE(5)
Print   VAR BIT

'======= INITIALIZE ===============================================================================
PORTB.5 = 1         ' set to avoid sending serial data garbage
Print   = 0

'======= PROGRAM ==================================================================================
ON INTERRUPT GOTO ISR

MAIN:
    IF PRINT THEN
        HSEROUT [SData]
        Print = 0
    ENDIF    
    GOTO MAIN
END    

' ====== INTERRUPT SERVICE ROUTINE ================================================================
    Disable
ISR:
    PRINT = 1
	HSerin [SData]
	Resume
    ENABLE

Looks like a silly question, but, can I trust this code? Will it work @ 100%? Could something make it hang or stop?

BTW, thanks for your code - I'm playing with it trying to understand it