2 line LCD on I2C pins
HollyMinkowski
Posts: 1,398
Since you can get a 2 line back lighted LCD on ebay
for 3.50 including postage and a 40pin dip ATmega1284P for
5.00 it seems like you could make a nice package for
< 10.00
Since the pins handling I/O for the eeprom are basically
unusable by the Propeller for any other duties it would
seem adding such an LCD display hooked to these lines
alongside the eeprom would be a good use of resources.
The ATmega has 128kb of flash and since the software to
control the LCD would be rather small then the rest could
be used by the prop as storage. The 20mips of processing
power of the 1284p and many of its I/O pins and peripherals would
also be usable by the prop. If you did a 4bit LCD controller
you would have a lot of 1284p I/O pins left over for other
uses.
This would add lots of I/O, memory, mips and 2line LCD while
using up no extra prop pins. It might be possible to store your Prop
data file inside the 1284p's flash and thereby completely
eliminate the eeprom chip too?
Seems like a good idea for a sub 10.00 booster for the Prop,
Has anyone done something similar?
EDIT:
Just had a thought. If you used a 28pin tiny88 (8kb flash)
and added on a directly wired 1gb microSD card then you
would be adding a gb of flash storage to the prop for roughly
the same price. Not sure about eliminating the eeprom though
since you would only have 8kb of flash in the tiny88 and you
would need to engineer a way to store the Prop's data file
on the microSD and send that to the prop quickly enough
for a normally fast start up.
The tiny88 is just 1.60 The drawback compared to the 1284P
is that you would have fewer I/O pins. And you would be forced
to use a 4bit interface to the LCD to still be able to add some I/O
pins for the Prop. You would also lose a few more of the Tiny's pins to
interface the SD card.
Post Edited (HollyMinkowski) : 6/6/2010 8:31:28 AM GMT
for 3.50 including postage and a 40pin dip ATmega1284P for
5.00 it seems like you could make a nice package for
< 10.00
Since the pins handling I/O for the eeprom are basically
unusable by the Propeller for any other duties it would
seem adding such an LCD display hooked to these lines
alongside the eeprom would be a good use of resources.
The ATmega has 128kb of flash and since the software to
control the LCD would be rather small then the rest could
be used by the prop as storage. The 20mips of processing
power of the 1284p and many of its I/O pins and peripherals would
also be usable by the prop. If you did a 4bit LCD controller
you would have a lot of 1284p I/O pins left over for other
uses.
This would add lots of I/O, memory, mips and 2line LCD while
using up no extra prop pins. It might be possible to store your Prop
data file inside the 1284p's flash and thereby completely
eliminate the eeprom chip too?
Seems like a good idea for a sub 10.00 booster for the Prop,
Has anyone done something similar?
EDIT:
Just had a thought. If you used a 28pin tiny88 (8kb flash)
and added on a directly wired 1gb microSD card then you
would be adding a gb of flash storage to the prop for roughly
the same price. Not sure about eliminating the eeprom though
since you would only have 8kb of flash in the tiny88 and you
would need to engineer a way to store the Prop's data file
on the microSD and send that to the prop quickly enough
for a normally fast start up.
The tiny88 is just 1.60 The drawback compared to the 1284P
is that you would have fewer I/O pins. And you would be forced
to use a 4bit interface to the LCD to still be able to add some I/O
pins for the Prop. You would also lose a few more of the Tiny's pins to
interface the SD card.
Post Edited (HollyMinkowski) : 6/6/2010 8:31:28 AM GMT
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Leon Heller
Amateur radio callsign: G1HSM
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*Peter*