How to Reset Osccal Value

[Pic2008]

Your syntax is wrong. Type the following in the code:

OSCCAL = $30

[Acetronics2]

Your syntax is wrong. Type the following in the code:

OSCCAL = $30

Hi,

You sure ???

From a µChip Datasheet ...

2.2.2.7 OSCCAL Register
The Oscillator Calibration register (OSCCAL) is used to
calibrate the internal 4 MHz oscillator. It contains 6 bits
to adjust the frequency up or down to achieve 4 MHz.
The OSCCAL register bits are shown in Register 2-7.
REGISTER 2-7: OSCCAL — OSCILLATOR CALIBRATION REGISTER (ADDRESS: 90h)

Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
- n = Value at POR ’1’ = Bit is set ’0’ = Bit is cleared x = Bit is unknown
R/W-1 R/W-0 R/W-0 R/W-0 R/W-0 R/W-0 U-0 U-0
CAL5 CAL4 CAL3 CAL2 CAL1 CAL0 — —
bit 7 bit 0
bit 7-2 CAL5:CAL0: 6-bit Signed Oscillator Calibration bits
111111 = Maximum frequency
100000 = Center frequency
000000 = Minimum frequency
bit 1-0 Unimplemented: Read as '0'
Legend:
R = Readable bit W = Writable bit U = Unimplemented bit, read as ‘0’
- n = Value at POR ’1’ = Bit is set ’0’ = Bit is cleared x = Bit is unknown

Alain

[Pic2008]

Hi,

You sure ???



Alain

Yes, I'm sure. greensasquatch pointed that the original value from the chip is 30H.

greensasquatch, without writing @ ORG 3FFh and @ RETLW 30h, have you tried the method I have written here?

[Acetronics2]

Hi,

Not so sure ...

as you write the cal value in a "non protected" memory location and not at the end of the program memory ...

you'll lose the cal value if you use the '675 for another program.

so it's much better to write it at the end of the program memory, as programmers will read it ( and preserve it ) if you do not remember what you had done ... some weeks later.

Alain

[Archangel]

Here is a copy / paste from one of my programs 12F675:

POKECODE @$3FF, $50  ' reintroduces osscal correction data
                         ' $3FF tells it where to code, $50 is the
                         ' Cal value unique to each individual chip.

[Pic2008]

Hi,

Not so sure ...

as you write the cal value in a "non protected" memory location and not at the end of the program memory ...

you'll lose the cal value if you use the '675 for another program.

so it's much better to write it at the end of the program memory, as programmers will read it ( and preserve it ) if you do not remember what you had done ... some weeks later.

Alain

There are two ways of doing it, either write to the OSCCAL directly or like you said, write at the end of program memory at 0x3FF.

Good point.