On Apr 2, 2008, at 4:20 PM, Doug Metzler wrote:
> has anyone successfully compressed a complete 5*7 LCD font into 256  
> bytes of EEPROM?

I've thought about it, especially since tables bigger than 256bytes  
can be such a pain. (but are you sure you want it in eeprom rather  
than flash?)

You have 35 bits per character.  It's probably not worthwhile trying  
to do that in less than 5 bytes, so the obvious encoding lets you  
have 51 characters.  There are 94 characters generally considered  
printable.  68 if you eliminate lower case.  The "squoze" character  
set (old-style symbol characters: 6 chars in 32 bits) has 40  
characters.  So squoze fits with no problems.  What do you consider  
complete? Nine characters might be considered to have a width of 1,  
and in general quite a few might have a width lower than 5, but then  
you have some sort of two-stage lookup and that takes up space  
elsewhere...
So I think I'd conclude that you can fit a USEFUL font subset in 256  
bytes pretty easily, but probably not a "complete" font...

BillW

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