Well after a few rounds with microchip sup****t I finally got to the bottom
of the problem. My solution stated early was not correct. The dummy write
I
was doing included this instruction (bcf EECON1,CFGS ,0) which can get
ramdomly set during a power. This instruction is not included in the
datasheet read/write data EEProm examples, I inserted it after I couldn't
get the write routine to work correctly. But everything is fine now, so if
anyone else has this problem be sure to clear this bit.
"bill" <williamsmith57@[EMAIL PROTECTED]
> wrote in message
news:_IqdnVaRQ5QlDFvanZ2dnUVZ_tSknZ2d@[EMAIL PROTECTED]
> Yes you are correct should of been _BORV_20_2L. I did try and increase
> value to _BORV_42_0L with no success. However I was able to resolve this
> problem, seems with slow Vdd rise times (<10ms) the EEPROM may get
locked.
> Doing a dummy write to an unused EEPROM location will unlock the EEPROM
> and stored values will be read correctly. Thank you for the response.
> "dk" <mcdivyakanth@[EMAIL PROTECTED]
> wrote in message
> news:8564459e-33ca-43c2-8826-45298130fadd@[EMAIL PROTECTED]
> On Feb 25, 2:05 pm, "bill" <williamsmit...@[EMAIL PROTECTED]
> wrote:
>> Hi All
>> I am currently using a 18f4431 to control motor position. During
program
>> execution I have a few variables I store to the internal Data EEProm.
>> Some
>> of these get updated every time the motor is commanded to move, and
some
>> only during a calibration routine which may only happen once. But all
>> variables get read during a power up. The problem is these varibles are
>> getting corrupt after a power down-power up. During exectution I am
>> reading
>> the data EEProm values and outputting them to a HyperTerm screen, so it
>> appears the are being stored Okay. I have the brown out voltage enabled
>> to
>> 2.0 v. I don't understand how come they are not correct after a power
>> down,
>> could anyone please Help.
>
> Suggest you to increase the brown out voltage. Also i fail to
> understand how you have set the BOV to 2.0 as datasheet tells me you
> can't set the BOV to 2.0V for 18F4431
>
> -dK
>
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