Program LCD messages into external EEPROM

TL · Joined: 15 Sep 2003 Posts: 75

Hi,

I’m using the 18F6720 and I believe the 128KB flash program memory may not be enough for my project. I’m thinking of putting all the LCD pre-defined messages (about 30KB) into external EEPROM such as the 24xx512 which has 64KB.

Does anyone know how I can program these LCD messages into the 24xx512, so that the 18F6720 can read them?

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

treitmey · Joined: 23 Jan 2004 Posts: 1094 Location: Appleton,WI USA

4. If you can afford it. And your into production((stable code)). You can have arrow do it for you.
http://www.arrownac.com/

kender · Joined: 09 Aug 2004 Posts: 768 Location: Silicon Valley

If your PIC has the means of connecting to the PC (such as RS232, USB, redio, etc), you can program the EEPROM thought the PIC. PIC would enter the "configuration mode", receive the strings from the PC and send them to the EEPROM via I2C.

By the way, Maxim has an app note describing a parallel port to I2C and SPI adaptor. It has the schematic and VB source code for the host PC application http://www.maxim-ic.com/appnotes.cfm/appnote_number/980

jecottrell · Joined: 16 Jan 2005 Posts: 559 Location: Tucson, AZ

My latest project had similar issues. Luckily I managed to survive with just the PIC EEPROM. If I had reached the point where I needed to use an external EEPROM my plans were to:

Write a small program to load the external EEPROM with the data I needed. Use my project board as a EEPROM programmer to load the small number of EEPROMs for my project. Then reload the actual project firmware. Quite simple approach for small numbers. If you have large numbers all the previous suggestions, obviously, make more sense.

Good Luck,

John

asmallri · Joined: 12 Aug 2004 Posts: 1634 Location: Perth, Australia

Another technique is to extend a bootloader. PIC18F bootloaders use "type 4" records (extended address information) to identify the target space (such as Program Memory, EEPROM, Config bits etc). You could define you own type 4 record and when your bootloader sees this it knows to program the external EEPROM. I often use this technique for programming slave devices off the PIC.
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Regards, Andrew

http://www.brushelectronics.com/software
Home of Ethernet, SD card and Encrypted Serial Bootloaders for PICs!!

TL · Joined: 15 Sep 2003 Posts: 75

Many thanks for all your helpful suggestions. We normally have test software programmed into the microcontroller to test its populated board before re-programming with the actual software.

Therefore, I think I’ll follow jecottrell’s advice in putting the LCD messages in the test software and write them to external EEPROM via I2C. We can then program the actual software to replace the test software in the microcontroller.