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TL
Joined: 15 Sep 2003
Posts: 75
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| Program LCD messages into external EEPROM |
 Posted: Mon Nov 14, 2005 6:03 am |
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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? |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Mon Nov 14, 2005 5:29 pm |
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| Quote: | | Does anyone know how I can program these LCD messages into the 24xx512. |
1. You can buy a eeprom programmer.
Search Google for: "eeprom programmer" price
2. You can build one. There are many websites with home made
eeprom programmers that connect to the PC parallel port.
Do a search on Google for these words (with the quotes):
"eeprom programmer" "parallel port"
3. You could also design your own programmer. Use a PIC with the
CCS i2c routines to do the programming. Have it receive a file
over the serial port from a terminal program, and program the
bytes into eeprom. This might require some handshaking or
spacing between the bytes, to allow for the write programming time. |
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treitmey
Joined: 23 Jan 2004
Posts: 1094
Location: Appleton,WI USA
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| Posted: Mon Nov 14, 2005 5:33 pm |
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4. If you can afford it. And your into production((stable code)). You can have arrow do it for you.
http://www.arrownac.com/ |
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kender
Joined: 09 Aug 2004
Posts: 768
Location: Silicon Valley
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| Posted: Mon Nov 14, 2005 5:44 pm |
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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 |
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jecottrell
Joined: 16 Jan 2005
Posts: 559
Location: Tucson, AZ
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| Posted: Mon Nov 14, 2005 6:34 pm |
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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 |
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asmallri
Joined: 12 Aug 2004
Posts: 1635
Location: Perth, Australia
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| Posted: Mon Nov 14, 2005 7:13 pm |
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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.
_________________
Regards, Andrew
http://www.brushelectronics.com/software
Home of Ethernet, SD card and Encrypted Serial Bootloaders for PICs!! |
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TL
Joined: 15 Sep 2003
Posts: 75
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| Thank you |
| Posted: Tue Nov 15, 2005 2:48 am |
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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. |
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