Problem with int_EXT execution during fgetc()

[JohnM]

Dear Colegues,

We are using version 3.203 of PCWH
PIC used is 18F452

We have 3 ISRs in our software. We are using

- one hardware serial port on #int_rda (9600)

- one software serial port with interrupt only for receiving on int_EXT2 (4800)

- one interrupt on #int_EXT





Our problem is that when we are in the ISR on int_EXT2 (interrupt driven software serial port), #int_EXT is nor working. In details we tested that fgetc(SOURCE2) can not be interrupted by int_EXT.

fgetc(SOURCE2) takes about 230 uS, so as result we are loosing some interrupts.

In order to solve this problem would be very useful to have source of your fgetc() you have implemented in this compiler. This give as ability to adopt it to our needs.

Our request is to be able to realize #int_EXT interrupts also during fgetc() execution.

Thank you very much for your prompt reply.

Best regards

JOHN







1)



//************************************************************************************

//we have a change to the RXD pin

#int_EXT

EXT_isr()

{

_rx.Periods[_rx.PeriodsWritePtr]=get_timer3();

set_timer3(0);

_rx.PeriodsWritePtr++;

_rx.PeriodsWritePtr&=RXPERIODSLEN;



//store period for process by background

//flip sensor for ISR

if (_intKind)

ext_int_edge(0,L_TO_H);

else

ext_int_edge(0,H_TO_L);

_intKind^=1;

}





2)



#int_rda

void serial_isr(void)

{



_USBserial.buffer[_USBserial.WritePtr]=fgetc(USB);

_USBserial.WritePtr++;

_USBserial.WritePtr&=MAXSERIALBUF;

if(_USBserial.WritePtr==_USBserial.ReadPtr)//buffer full

{

_USBserial.ReadPtr++;

_USBserial.ReadPtr&=MAXSERIALBUF;

}

}







3)



int_EXT2

void SOURCE2RcvInt(void)

{

_SOURCE2serial.buffer[_GPSserial.WritePtr]=fgetc(SOURCE2); // 210 uS

inline_test();

_SOURCE2serial.WritePtr++;

_SOURCE2serial.WritePtr&=MAXSERIALBUF;

if(_SOURCE2serial.WritePtr==_SOURCE2serial.ReadPtr)//buffer full

{

_SOURCE2serial.ReadPtr++;

_SOURCE2serial.ReadPtr&=MAXSERIALBUF;

}

}







//************************************************************************************

//we have a change to the RXD pin

#int_EXT

EXT_isr()

{

_rx.Periods[_rx.PeriodsWritePtr]=get_timer3();

set_timer3(0);

_rx.PeriodsWritePtr++;

_rx.PeriodsWritePtr&=RXPERIODSLEN;



//store period for process by background

//flip sensor for ISR

if (_intKind)

ext_int_edge(0,L_TO_H);

else

ext_int_edge(0,H_TO_L);

_intKind^=1;

}

[PCM programmer]

[C-H Wu]

>> Our problem is that when we are in the ISR on int_EXT2 (interrupt driven software serial port), #int_EXT is nor working.

If what you want is to interrupt another interrupt, i.e. nested interrupt ?

try this:

#int_EXT FAST // FAST keyword making #int_EXT become high-priority
EXT_isr()
{ ...
}

then this high-priority EXT_isr() can interrupt low-priority ISR's.
I don't quite remember if the #int_EXT is high priority be default. Anyway, check the interrupt priority bit setting and also make sure that GIE is not disabled in other ISR's.

for more details, see c:\PICC\Readme.txt

[ckielstra]

>> Our problem is that when we are in the ISR on int_EXT2 (interrupt driven software serial port), #int_EXT is nor working.

From the PIC18Fxx8 manual: