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LCD Inop After Sleep

 
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jecottrell



Joined: 16 Jan 2005
Posts: 559
Location: Tucson, AZ

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LCD Inop After Sleep
PostPosted: Sat Apr 29, 2006 4:01 pm     Reply with quote

Hello All,

18F4620
3.236

I've got a character LCD connected to port_d and I'm using the standard lcd.c driver. When I put the PIC to sleep the LCD won't work upon wake-up. I init it and do everything just like upon power up.

However, if I reset_cpu() I can get the LCD to work, but that generates another problem. I use a momentary switch to interrupt RB6 to wake the processor. When I push the button to wake the CPU, the interrupt 'hangs' i.e. fires continuously.

If I disable the portb interrupts in the ISR the interrupt no longer 'hangs', but I can never get the portb interupt re-enabled....

Any ideas?

Thanks,

John
PCM programmer



Joined: 06 Sep 2003
Posts: 21708

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PostPosted: Sat Apr 29, 2006 11:03 pm     Reply with quote

The test program shown below works OK. I tested it on a PicDem2-Plus,
which has the LCD on pins D0-D3 and A1-A3. To get the INT_RB
interrupt, I pulled out the ICD2 connector and jumpered the push-button
switch on B0 over to pin B7. When it's in Sleep mode, I push the
button and it displays this on the LCD:
Quote:

Wake up
Hello World
Sleeping

I can do that repeatedly.

Code:

#include <16F877.H>
#fuses XT, NOWDT, NOPROTECT, BROWNOUT, PUT, NOLVP
#use delay(clock=4000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7, ERRORS)

#include "flex_lcd.c"

#int_rb
void rb_isr(void)
{
   
disable_interrupts(INT_RB);   
}   

//======================================
void main()
{
int8 i;
int8 c;

lcd_init();

port_b_pullups(TRUE);

while(1)
  {
   lcd_putc("\fHello World");
   delay_ms(2000);
       
   c = input_b(); // Clear "change condition" on Port B
   clear_interrupt(INT_RB);    // Clear RBIF flag
   enable_interrupts(INT_RB);  // Enable RB interrupts
   enable_interrupts(GLOBAL);

   lcd_putc("\fSleeping");
   
   sleep();
   
   lcd_putc("\fWake up");
   delay_ms(2000);     
  }

}
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