Member Since: October 30, 2009

Country: United States

  • If I could change the hardware, I’d also make these changes:
    * 5V for AVR, 3.3V for flash chip. This way, it’d work with all AVR programmers, and could record input from normal 5v circuits without external voltage dividers.
    * Onboard voltage divider network (6 resistors and a 3-DIP switch?), for recording inputs above the ADC voltage.
    * A more compatible power plug!
    * I don’t care much about this, but an external 12.8mhz oscillator would allow the ADC to run at its recommended maximum rate (200khz), for the highest possible sampling rate.

  • There are improvements that could be made to the code. :-)
    * The current code wastes a lot of space. It could get 60% more recording time from the same amount of memory.
    * The hardware should be able to record seamlessly at up to ~14000 samples/second, so a variable recording rate would be nice. At low rates, it could use the ADC sleep mode and averaged sampling to increase precision.
    * The current code uses only one flash buffer. It could instead fill one buffer while the other is being committed, for a higher maximum recording rate.
    * By turning off unused channels, you can record at a higher rate or for a longer time on the remaining channels, and reduce time spent waiting for ADC stabilization. In the common case of only one channel, you could get ~9000 samples/sec at the current CPU speed, or 13-14k samples/sec at a higher speed.
    * The current code constantly uses 100% CPU time, even between samples and after the memory is full. It could be using low-power sleep modes.
    I could implement those pretty easily if I could get it to work at all. :-)

  • Running on 5 volts would also be good because then I could hook it up to typical 5V circuits without needing to hook up 3 voltage divider circuits too.

  • The power plug is frustratingly incompatible with my existing battery packs and connectors (mostly from Pololu). They’re almost exactly the same, but the plug on the uLog is a bit too narrow…
    I believe Pololu connectors would accept Sparkfun batteries, but Sparkfun connectors don’t accept Pololu batteries. It’d be nice if those were compatible.
    Not quite sure what to do now… I have a few spare connectors, but they’re through-hole and not surface mount. And I don’t have a 3.3V regulator to apply power directly to the pins. :-(
    Also, not many programmers work on 3.3V. Most require 5V.
    Would the device work on 5 volts?

No public wish lists :(