A very useful cheap and cheerful IR remote control is let down by somewhat inadequate memory.
it uses a 24LC32B Is it likely or unlikely that if I changed it to a 128, that the firmware on the ucontroller would limit the running to 32K/ not work at all or allow running out to 128K ? As serial linkage I'm hoping it would not be limited
The firmware likely doesn't know about more than 32K.
If it can't address more memory, you could use two (or three) memory chips with a switch to select which one to use.
Isaac
somewhat
firmware on
What would be the minimum number of lines that would need switching ? Could you leave A0,A1,SDA paralleled and just switch SCL and WP?
Check what the data sheet says ...
Isaac
The original design has the A0 and A1 pins tied off in some particular state (most likely at GND). You could arrange your additional chips with all connections in parallel except for the A0 and A1 pins. Your switching could the simply be setup to present just one chip at a time with the A0 and A1 pins set to levels that match the original design. This way that would be the chip to respond when the controller chip sends out the I2C slave address.
Supporting two chips like this has trivially simple switching of just one of the addressing lines. Just make sure that you _do_ _not_ ever have two or more chips with the A0 & A1 levels being the same and matching the original design settings.
allow
So any switching has to be break before make combined with gating off all switching while any activity
But, that's not the memory; that's the NONVOLATILE memory, possibly with some on-chip FLASH ROM. To run six devices (be generous, eight device codes), with a generous number of buttons (30? 50?) each taking an eight-bit data value, is still only 400 bytes. Digit codes are regular enough that they can be compressed into a rule, and macros can be reused...
If one exercises a small amount of cleverness, 32k bits (about 4100 bytes) should be enough to store device and key assignments. With larger amounts of cleverness, it's a GENEROUS amount of memory.
But, that's not the memory; that's the NONVOLATILE memory, possibly with some on-chip FLASH ROM. To run six devices (be generous, eight device codes), with a generous number of buttons (30? 50?) each taking an eight-bit data value, is still only 400 bytes. Digit codes are regular enough that they can be compressed into a rule, and macros can be reused...
If one exercises a small amount of cleverness, 32k bits (about 4100 bytes) should be enough to store device and key assignments. With larger amounts of cleverness, it's a GENEROUS amount of memory.
No. No damage will occur. But if two chips are addressed simultaneously, you may get weird codes. Just don't be pressing a command button while throwing the selector switch.
Isaac
If you hit the EEPROM hard with a hammer it might enlarge (and spread out)
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