WRITE prob during power cycle 18f6722

[jellis00]

this is to be fabricated by the hundreds, price is an issue.

What about the onboard "HLVD"

But then again its all in ASM. It talks about these steps

1. Write the value to the HLVDL3:HLVDL0 bits that
selects the desired HLVD trip point.
2. Set the VDIRMAG bit to detect high voltage
(VDIRMAG = 1) or low voltage (VDIRMAG = 0).
3. Enable the HLVD module by setting the
HLVDEN bit.
4. Clear the HLVD interrupt flag (PIR2<2>), which
may have been set from a previous interrupt.
5. Enable the HLVD interrupt if interrupts are
desired by setting the HLVDIE and GIE bits
(PIE2<2> and INTCON<7>). An interrupt will not
be generated until the IRVST bit is set.

How do I write these values that it needs. Can I do it in PicBasic pro?

I have been working with the onboard HLVD module in a 18F4550 to use it as a low voltage monitor for my application. I am posting my current PBP code below that is suppose to do steps 1-5 you list above that are called out in the Data Sheet. I am prettry sure this is the right code, but it wasn't working, so I ran an ICD on it and discovered that when it gets to this procedure which is located in my main program loop, the first HLVDCON statement executes to clear HLVDCON.4, however the next statement (HLVDCON = %00011101) which is suppose to perform steps 1-3 in your above listing, doesn't execute....nor do any of the remaining statements in this process block execute...instead the program always jumps to an Interrupt Service Routine that is suppose to service a DT_INTS-18 interrupt triggered by a real-time clock. However the RTC interrupt isn't timed to happen when this happens. I can't figure out why this this HLVDCON statement is not executing and the rest of this block is not executing in the main loop before the interrupt happens.

Can anyone advise me what is happening here and how to fix it??

' Test for low battery conditon
        ' Set registers for using HLVD feature
            HLVDCON.4 = 0   'Disable the module by clearing HLVDCON.4
            ' Set the trip point at Vdd=4.4 vdc by setting HLVD3:HLVDL0=1101
            ' Set VDIRMAG=0 (HLVDCON.7) to detect low voltage transition
            ' Enable the HLVD module (HLVDCON.4=1)
              HLVDCON = %00011101
            ' Clear the HLVDIF interrupt flage (PIR2<2>)
              PIR2.2 = 0 
            ' Enable the HLVD interrupt
              PIE2.2 = 1
              INTCON.7 = 1
            ' Set IRVST bit (HLVDCON.5 =1) to allow interrupt generation
              HLVDCON.5 =1
        If PIR2.2 =1 THEN ' Test for HLVD interrupt (HLVDIF bit = 1)
           For I = 0 TO 4 ' Blink the RED LED 5X as low battery warning
               High LED_RED   
               Pause 500
               LOW LED_RED
               pause 500
           next
        ENDIF

[jellis00]

For those people who might visit this thread I will post the solution to using the HLVD module as I was able to resolve with some offline support from Darrel Taylor.

First, you need to make sure you have setup a DT_INTS-18 interrupt for the HLVD module by inclusion of this code:

ASM
INT_LIST  macro    ; IntSource,         Label,  Type, ResetFlag?
        ;INT_Handler   USB_Handler
        INT_Handler   HLVD_INT,        _LowVolt, PBP,  yes
    endm
    INT_CREATE                ; Creates the interrupt processor
ENDASM

Then you need to insert this in your code ahead of the main loop to setup the use of the HLVD module.

       
 ' Set registers for using HLVD feature
          ' Step 1-Disable the module by clearing HLVDCON.4
        		HLVDCON.4 = 0 	' Implement Step 1           
          ' Step2 HLVD3:HLVDL0=1101 'Set the trip point at Vdd=4.33 vdc
          ' Step3 HLVDCON.7=0 'Set VDIRMAG=0 to detect low voltage transition
          ' Step4 HLVDCON.4=1 'Enable the HLVD module
              	HLVDCON = %00011101   'Implements Steps 2-4
          ' Clear the HLVDIF interrupt flag (PIR2<2>)
 		        PIR2.2 = 0 
          ' Enable the HLVD interrupt
@    INT_ENABLE   HLVD_INT ; enable HLVD interrupt

Then you need to create an interrupt service routine (ISR) nead the end of your code as follows:

LowVolt:
   ' Blink LED_RED 5X to indicate Low Battery voltage detected
        For i = 0 to 4
           HIGH LED_RED
           Pause 500
           LOW LED_RED
           PAUSE 500
        Next
@ INT_DISABLE HLVD_INT      ; This statement very important, else code will lockup on exit
                                            ; from the ISR to main program. 
        ' Resume Main Program
@ INT_RETURN
'------------------{ End of Interrupt Handlers }-------------------------

Hope this might help someone!