We have a 5x5 keypad matrix we need to interface to. The bitsyX manual indicates up to a 4x5 matrix. There are other I/O lines available for use with the matrix and the ADSmartIO docs indicate a mode 1 setting that has up to a 7x7 matrix.
Can the BitsyX be made to scan the matrix in this way, or should I take a totally different approach?
The BitsyX is set up for a keypad up to 4x5. A larger keypad scan might be possible, but would probably require reconfiguration of the board hardware and an addition to the ADSmartIO firmware. It could be cost-effective if you're headed toward volume production.
Another option might be to implement your own keypad scan with the XScale digital I/Os. There are ten IOs available (EIO0-EIO9) that are located on headers J3 and J10. If you ran the scan on a software timer, overhead could be fairly low.
I'll look at implementing my own keypad routine. Since this is battery operated, I did have another idea that might work. I could use a Phillips PA9535 I2C I/O port expander. It has interrupt capability, so I wouldn't need to scan all the time and could wake the system on keypress.
That leads to another question. Since the manual suggests not to use the ADSmartIO I2C port, does your I2C test code for the RTC and temperature use the Xscale I2C port?