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Low Voltage Detect interrupt CCS Forum Index -> General CCS C Discussion View previous topic :: View next topic Author RobS

Message Low Voltage Detect interrupt Posted: Wed Sep 28, 2005 4:52 pm

Joined: 29 Jan 2005 Posts: 10

I'm using the PIC18LF870/18LF8722. CCS Ver 3.23. I want to use #int_lowvolt interrupt to write to internal EE when VDD falls below a certain value. Do any fuses need to be set? What is a good way to set the LVDCON register bits? thanks

PCM programmer

Joined: 06 Sep 2003 Posts: 6775

Posted: Thu Sep 29, 2005 3:53 pm

Here is a Low Voltage Detect test program for the 18F452. If you use a variable DC power supply which is initially set at 5.0v, and you slowly reduce the voltage to 4.60v, at that point you will get this displayed: Quote: Low voltage Low voltage Low voltage Low voltage Low voltage

When you adjust the voltage above 4.60v, the messages will stop. Initially, I had some code to print "AAAAA" to let me know it was running, but I didn't need that in the final version, so it's commented out. Also note that for your PIC, you have the ability to trigger on "above" or "below" the LVD voltage. An extra parameter may be used to select this in the setup_low_voltage() function. See notes in code, below. Code: #include <18F452.h> #fuses XT,NOWDT,PUT, BORV27,NOLVP #use delay(clock=4000000) #use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7, ERRORS) #byte LVDCON = 0xFD2 #bit IRVST_BIT = LVDCON.5 #byte PIR2 = 0xFA1

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01.3.2007 г. 09:53

CCS :: View topic - Low Voltage Detect interrupt

http://www.ccsinfo.com/forum/viewtopic.php?t=24577

#bit LVDIF_BIT = PIR2.2 int8 lvd_flag; #int_lowvolt void lvd_isr(void) { lvd_flag = TRUE; disable_interrupts(INT_LOWVOLT); } int8 wait_for_lvd_to_stabilize(void) { int16 timeout_count; timeout_count = 0xFFFF; // Many milliseconds while(timeout_count--) { if(IRVST_BIT) return(TRUE); } return(FALSE); } //==================================== void main(void) { printf("Start\n\r"); setup_low_volt_detect(LVD_46); //setup_low_volt_detect(LVD_46 | LVD_TRIGGER_BELOW); //For 18F8722 if(wait_for_lvd_to_stabilize() == FALSE) { printf("Low Voltage Detect module didn't stabilize\n\r"); while(1); // Wait here forever } LVDIF_BIT = 0; // Clear the LVD interrupt flag enable_interrupts(INT_LOWVOLT); enable_interrupts(GLOBAL); while(1) { if(lvd_flag == TRUE) { printf("\n\rLow voltage\n\r"); lvd_flag = FALSE; LVDIF_BIT = 0; // Clear the LVD interrupt flag enable_interrupts(INT_LOWVOLT); } // delay_ms(500); // printf("A"); } } Douglas Kennedy

Joined: 07 Sep 2003 Posts: 366 Location: Florida

PCM programmer

Joined: 06 Sep 2003 Posts: 6775

2 от 3

Posted: Fri Sep 30, 2005 10:15 am

Is setup_low_volt_detect ( ) a built in CCS function?

Posted: Fri Sep 30, 2005 10:27 am

Yes, it's in the current manual.

01.3.2007 г. 09:53

CCS :: View topic - Low Voltage Detect interrupt

http://www.ccsinfo.com/forum/viewtopic.php?t=24577

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01.3.2007 г. 09:53