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larny
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Joined: 31/10/2011
Location: Australia
Posts: 346

Posted: 11:09pm 06 Jun 2019

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I have successfully written many PIC programmes in the past.
However, today for the first time, I tried to enter data into the EEPROM via MPLAB.
The result is rather puzzling & I can't see how to fix it.
See the attachment.

Obviously, I must be doing something wrong but can't see what.

Any advice will be appreciated.

Edited by larny 2019-06-08

trippyben

Regular Member

Joined: 26/06/2011
Location: Australia
Posts: 91

Posted: 08:41am 07 Jun 2019

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Use de to define eeprom constants

org 0x2100
de 0x05,0x03,0x11

check the mplab help file for assembler directives

Volhout
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Joined: 05/03/2018
Location: Netherlands
Posts: 5089

Posted: 09:07am 07 Jun 2019

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Dear Larny,

As mentioned by trippyben, EEPROM can be set during programming of the chip.

If you need to program the EEPROM from your own code, you must use a different method. EEPROM is not as fast as RAM.

There is an EEPROM address register EEADR, and eeprom data register EEDAT that must be filled with the correct address and data, and then a write cycle must be stated through setting a write bit in the eeprom command register. Then you must poll the ready bit in the status register to see if the writing is finished. Byte for byte....

Look at the datasheet of the actual chip you are using. Most cases the procedure and basic code is detailed out.

Regards,

Volhout

PicomiteVGA PETSCII ROBOTS

larny
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Joined: 31/10/2011
Location: Australia
Posts: 346

Posted: 09:37am 07 Jun 2019

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trippyben said Use de to define eeprom constants

org 0x2100
de 0x05,0x03,0x11

check the mplab help file for assembler directives

Thanks very much trippyben. That's exactly what I wanted to know.

In looked at the help file but could not see anything relevant. I'll have another look tomorrow.

larny
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Joined: 31/10/2011
Location: Australia
Posts: 346

Posted: 09:40am 07 Jun 2019

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Volhout said Dear Larny,

As mentioned by trippyben, EEPROM can be set during programming of the chip.

If you need to program the EEPROM from your own code, you must use a different method. EEPROM is not as fast as RAM.

There is an EEPROM address register EEADR, and eeprom data register EEDAT that must be filled with the correct address and data, and then a write cycle must be stated through setting a write bit in the eeprom command register. Then you must poll the ready bit in the status register to see if the writing is finished. Byte for byte....

Look at the datasheet of the actual chip you are using. Most cases the procedure and basic code is detailed out.

Regards,

Volhout

Thanks for the reply. I wanted to know how to programme the EEPROM in MPLAB. So trippyben's answer was exactly what I wanted. I know how to programme the EEPROM in code as you described.

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