'74/74A, C84/F84 differences.'
|Recent questions on the 74 and 84 from a programming point of view have
prompted me to repost the response to two messages that were written by
Jim Robertson of Newfound Electronics.
Jim currently isn't on the PICLIST, but has reasonable experience with
devices, as he is the designer of the Warp-3, PP1, and Warp-17
74 and 74A
At 10:28 AM 1/10/97 GMT+1100, you wrote:
Reverse the PWRTE bit, if you want it "ON" select it as "OFF" and vice
Do not code protect the 16C74A! You will not be able to erase the code
protection bits if you do.
The Brownout will not be available on you "A" part. It will (should!) be
turned "OFF" by default by your programmer.
There are extra code protect bits in the "A" part but as you are not
programming them they do not matter.
All the other config bits, ID etc are the same!
Just remember to not code protect the "A" part and you should be ok.
C84 and F84
At 09:48 AM 1/16/97 -0500, you wrote:
>Please excuse my confusion. What is the difference between the
>EEPROM 16C84 and the FLASH 16F84? I know the 'F has more RAM bytes,
>but aside from this, what's the practical difference? Is there
>any difference in programming, number of write cycles, etc?
16F84 has PWRTE bit reversed (like ALL newer parts) when compared to the
16C84. All the spare config word bits in the 16F84 are used for code
protection. The effect of code protecting a 16F84 is different from a
(If you want to know the esoterica of it all download the programming
form the microchip web page but it usually is of little interest to the
"man in the street.")
Programming wise, you can program the 16F84 as a 16C84. Remember to
the code protect bit and don't expect code protection to be the same.
Don McKenzie dontronics.com donhttp://www.dontronics.com
SLI, the serial LCD that auto detects baud rates from 100 to 125K bps.
SimmStick(tm) A PIC proto PCB the size of a 30 pin Simm Memory Module.
Covers all versions of the PIC16cxx family plus the Atmel AT89C2051.
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