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Discussion Groups | M68HC11 | EPROM

Technical discussions about Freescale Microcontrollers: M68HC11. (Freescale Semiconductor is a Subsidiary of Motorola).

EPROM - bal_gill21 - Feb 2 14:48:00 2005


hi all,
I have a program that is working perfectly on my development system.
The program length is just under 1300 bytes. I have programmed a
68HC711E9 chip as it has 12K EPROM, the program resides in EPROM and
data storage resides in EEPROM. Temporary storage takes place in
EPROM where the program is. However my program works very slowly ie
where I am waiting for my display to update after 4 seconds precisely
it updates after approximatly 2 minutes and incorrecly display just
after it has written/read EPROM. Is this because EPROM is not meant
for flash writing?. Thanks in advance guys

Bal




Re: EPROM


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Re: EPROM - Tony Papadimitriou - Feb 2 15:11:00 2005

----- Original Message -----
From: "bal_gill21" <>
To: < > I have a program that is working perfectly on my development system.
> The program length is just under 1300 bytes. I have programmed a
> 68HC711E9 chip as it has 12K EPROM, the program resides in EPROM and
> data storage resides in EEPROM. Temporary storage takes place in
> EPROM where the program is. However my program works very slowly ie
> where I am waiting for my display to update after 4 seconds precisely
> it updates after approximatly 2 minutes and incorrecly display just
> after it has written/read EPROM. Is this because EPROM is not meant
> for flash writing?. Thanks in advance guys

Your development system is probably emulating EPROM with RAM or EEPROM/Flash
so it can be altered.

I presume you observe at least all of the following:

1. You only write once at each temporary location (i.e., permanently), since
you can't erase.
2. [1] implies you keep advancing the temporary location for each write, and
not overwriting.
3. You have programming voltage enabled during the write.
4. You're using the correct programming algorithm (similar to writing to
EEPROM).
5. You are writing from a routine that runs off RAM or EEPROM, but not
EPROM.

I haven't tried doing what you are so I'm not 100% it works even if you
observe all of the above. I may be forgetting something crucial.

Now, may I ask, WHY? You have both RAM and EEPROM to use for temporaries.
If it's only for the duration of the run, use RAM, if you want it remembed
at next power up, use EEPROM.

If the reason you had to use EPROM is both RAM and EEPROM are too small for
what you need to store then either use external memory or choose another
chip.

I believe you need this to store data (not executable code) so a serial
(e.g., SPI) EEPROM can be used that will not eat up your available pins.
You can also use MMC cards (in SPI mode) that come to sizes as large as 4GB
(last time I checked).

> Bal





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