> Van: Matt Bennett <mjb@SCDH-99.UMD.EDU>
> Aan: PICLIST@MITVMA.MIT.EDU
> Onderwerp: 16F84 "Bulk" erase problems.
> Datum: zondag 15 maart 1998 23:46
>
> I've built my own programmer (a serial programmer for both the EPROM
> and Flash parts) and it programs great.  I'm having problems with the
> "bulk" erasing of the program and data areas.  My first problem is
> ambiguity in the data sheet.  In the data sheet it reads:
>
> Bulk Erase Program Memory
> To perform a bulk erase of the program memory, the following
> sequence must be performed.
> 1. Do a "Load Data All 1's" command.
> 2. Do a "Bulk Erase User Memory" command.
> 3. Do a "Begin Programming" command.
> 4. Wait 10 ms to complete bulk erase.
>
> But there are two "load data" commands, one for "load data for program
> memory", (000010) and the other, "load data for data memory" (000011).
> Ok, I assumed that if I was erasing  the program area, I'd use "load
> data for program memory", and similarly for the data area.  Sounds
> logical to me, but... it doesn't work.
>
> It *does* seem to erase the memory location that I'm currently at,

Correct that : Your _overwriting_ the current memory location.
(Just change step #1's data and observe the result ...)

> in either the program or the data area, but I was under the impression
> that a "bulk" erase would erase *all* of the respective memory locations
> (data or program).

Don't correct that ;-)  That's what it's supposed to do !
>
> So, does the "bulk erase" erase one or all memory locations, and
> if it does erase them all, how do you actually do it?  Have you
> made the procedure in the data sheet actually work?

I've had the same problem with a 16C84 and contacted my supplier, and
still have no answer (after 4-and-a-half months).  But ... Fiddeling around
(and reading this mailing-list) I've found the solution to _my_ problem:
just swap step 2 & 3.

If that doesn't work, add another 'Begin programming' after the
'Bulk-erase'
command.

> If you're the one who helps me solve this problem, I'll treat you
> to your favorite coffee/tea/soda/beer the next time you are in
> the Washington, D.C. area!

Thanks! I'll keep that in mind.
> Matt
>
> mjb@hazmat.com              |
> http://www.hazmat.com/~mjb/ |

Greetz,
   Rudy Wieser