INT_RB and USART

[julius]

Hello,

It is needed to sampling RB7 by INT_RB interrupt.
all other pins PIN_B6,B5 are not used, and of course pulled up.

I have very surprised that RB4 input configured as RXD
generating INT_RB interrupt on serial data reception.

In other words if PIC USART working on high baudrates such 57600,
there is not possible to use INT_RB.
every changes in RXD will generate INT_RB routine.

this is about 18F1320 part.

Is there anybody to help me?

Julius

[valemike]

My first guess is that you are using the software UART ccs libraries. If you were to make it use the hardware usart module in the PIC, you shouldn't be getting those interrupts.

[julius]

Of course UART is enabled by hardware by register RCSTA TXSTA... directly using
NOT #use RS232 (),

By 18F1320 datasheet , PIN_B4 / RX / DT only port as analog input setting, will disable TTL input.

I have some projects with RB changes and USART using also, but with part 16LF876 without problems.

julius

[PCM programmer]

[Julius]

Im not using the CCS #use RS232(...)

here is init statements in main() {

set_tris_b(0b10011010); // B7 input for qaudr.encoder, B4 RXD
port_b_pullups(TRUE); //

// ---- ASYNC PORT INIT ---
SPBRG= 62; // 9600 baud on 38.400MHz = XTAL9.600MHz x 4PLL
BAUDCTL = 0;
TXSTA = 0x20; // BRGH=0
RCSTA = 0x90;

RBIP=1; // priority na PB change interrupt
enable_interrupts(INT_RDA);
RBIE=1; // PORTB change INT enable
enable_interrupts(GLOBAL);

while(1) { // never ending story

delay_ms(200); // restart_wdt
printf(myputc,"%u",count); // count is incremented in RB change handler
}
==================


so, in the #INT_RB handler it is possible to count++ variable
and in the main scope printing the count

on any serial character sending to PIC PIN_B4 INT_RB will occur depending the character, such SPACE = 0x20 makes cca 4 interrupts
start bit, databit, stop bit...

I will try the delay_ms() remove from code, its unknown procedure sometimes from CCS.

Julius

[Julius]

Im not using the CCS #use RS232(...)

here is init statements in main() {

set_tris_b(0b10011010); // B7 input for qaudr.encoder, B4 RXD
port_b_pullups(TRUE); //

// ---- ASYNC PORT INIT ---
SPBRG= 62; // 9600 baud on 38.400MHz = XTAL9.600MHz x 4PLL
BAUDCTL = 0;
TXSTA = 0x20; // BRGH=0
RCSTA = 0x90;

RBIP=1; // priority na PB change interrupt
enable_interrupts(INT_RDA);
RBIE=1; // PORTB change INT enable
enable_interrupts(GLOBAL);

while(1) { // never ending story

delay_ms(200); // restart_wdt
printf(myputc,"%u",count); // count is incremented in RB change handler
}
==================


so, in the #INT_RB handler it is possible to count++ variable
and in the main scope printing the count

on any serial character sending to PIC PIN_B4 INT_RB will occur depending the character, such SPACE = 0x20 makes cca 4 interrupts
start bit, databit, stop bit...

I will try the delay_ms() remove from code, its unknown procedure sometimes from CCS.

Julius