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Discussion Groups | 68HC12 | How to access internal EEPROM from external flash memory(68HC812A4)

Join our technical discussions about Freescale Microcontrollers: M68HC12. (Freescale Semiconductor is a Subsidiary of Motorola).

How to access internal EEPROM from external flash memory(68HC812A4) - Mansukh Sheliya - Jul 22 4:38:00 2002

Hi All,
In my application, I am using 68HV812A4 in Normal Expanded mode. I want to store some variables inside the 4KB EEPROM. I don't know- How to assign the perticular EEPROM address to my variable which I want to store inside the internal EEPROM? Can anybody help to solve my problem?
EEPROM access sequence is given in its datasheet and I have written a code for accessing the EEPROM appropriately but I want the variable assignment method.

Mansukh Sheliya
Amtel Security Systems Inc.




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Re: How to access internal EEPROM from external flash memory(68HC812A4) - Mike Burgess - Jul 23 12:52:00 2002

Mansukh,
It depends on whose tools you re using.

For Cosmic C compiler, they have an extended keyword off "eeprom" when this
is used in conjunction
with a variable, that variable is placed in the eeprom. You then define
the location of the eeprom with the linker.

Regards,
Michael H. Burgess
Sr. Design Engineer
Industrial Scan Inc. ----- Original Message -----
From: "Mansukh Sheliya" <>
To: <>
Sent: Monday, July 22, 2002 5:38 AM
Subject: [68HC12] How to access internal EEPROM from external flash
memory(68HC812A4) > Hi All,
> In my application, I am using 68HV812A4 in Normal Expanded mode. I want to
store some variables inside the 4KB EEPROM. I don't know- How to assign the
perticular EEPROM address to my variable which I want to store inside the
internal EEPROM? Can anybody help to solve my problem?
> EEPROM access sequence is given in its datasheet and I have written a code
for accessing the EEPROM appropriately but I want the variable assignment
method.
>
> Mansukh Sheliya
> Amtel Security Systems Inc. >
>
> --------------------------------------------------------
> To unsubscribe from this group, send an email to: > To learn more about Motorola Microcontrollers, please visit
> http://www.motorola.com/mcu



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RE: How to access internal EEPROM from external flash memory(68HC812A4) - Mansukh Sheliya - Jul 24 3:12:00 2002

Mike,
My current mapping is:
0000-6FFF for Direct Data space
7000-7FFF for DPAGE, we are nor using at present
8000-BFFF for PPAGE
C000-C7FF for registers and chip selects
C800-CBFF for RAM
CC00-FFFF for Direct memory space(main()) and Interrupt vector table

I have your code for your Barcode application. In this application you have used EEPROM(written code for accessing EEPROM using its accessing sequence). I have tried to write using this in Normal Expanded wide mode and I am succeed to write but after putting the processor in Single chip mode, I have checked the location where I have tried to write - it was unchanged.
Yes, In Cosmic C compiler they have a special keyword @eeprom for accessing EEPROM. Can you give one example for Cosmic compiler? One more thind I would like to ask is that -- Is it required to disable all interrupt while accessing the EEPROM. And When I kept the EEPROM enable for permenant at any location in 64KB, it was stopping the accessing of external part where the mapping is clashing with EEPROM.
Hope this may help to you for exploring me for EEPROM handling in Normal expanded mode.

Regards,
Mansukh Sheliya
Amtel security systems Inc. -----Original Message-----
From: Mike Burgess [mailto:]
Sent: Tue 7/23/2002 11:22 PM
To:
Cc:
Subject: Re: [68HC12] How to access internal EEPROM from external flash memory(68HC812A4)
Mansukh,
It depends on whose tools you re using.

For Cosmic C compiler, they have an extended keyword off "eeprom" when this
is used in conjunction
with a variable, that variable is placed in the eeprom. You then define
the location of the eeprom with the linker.

Regards,
Michael H. Burgess
Sr. Design Engineer
Industrial Scan Inc. ----- Original Message -----
From: "Mansukh Sheliya" <>
To: <>
Sent: Monday, July 22, 2002 5:38 AM
Subject: [68HC12] How to access internal EEPROM from external flash
memory(68HC812A4) > Hi All,
> In my application, I am using 68HV812A4 in Normal Expanded mode. I want to
store some variables inside the 4KB EEPROM. I don't know- How to assign the
perticular EEPROM address to my variable which I want to store inside the
internal EEPROM? Can anybody help to solve my problem?
> EEPROM access sequence is given in its datasheet and I have written a code
for accessing the EEPROM appropriately but I want the variable assignment
method.
>
> Mansukh Sheliya
> Amtel Security Systems Inc. >
>
> --------------------------------------------------------
> To unsubscribe from this group, send an email to:
>
>
> To learn more about Motorola Microcontrollers, please visit
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