Still working on my low-cost scope, currently battling some issues with unstable trigger positions (the scope very obviously waits for a trigger, but then seems to have variable delay), but other than that - if I use single-shot acquisition - my breadboarded version produces crisp, clean, virtually noise-free signal traces up close to its theoretical limit (recognizable sine waves up to about 150 kHz without interpolation, and if you only need approximate frequency information I got usable results up to around 300 kHz). Even without any optimizations (like hwserial instead of sertxd) I get 1.5 screen refreshs per second.
But now to my question:
Since I'd like to be able to go to low samples rates as well, does anybody know how to slow down PWM on an 28X1? In particular on the "classic" PWM pin 1, because I'd like to reserve the 4 hardware PWM pins for other purposes (to run at a slower period, used for analog control of trigger threshold and the like). I'm running the 28X1 at 16MHz clock (to maximize the acquisition and transfer speed), so the slowest PWM is 16 kHz - which means I can't even look at a full 50 Hz (20ms) period because the 256 sample record spans only 16ms. One option would be of course to slow down the clock frequency (internal oscillator instead of external resonator), but that would affect the ability to receive full-speed RS-232 commands from the PC unless I keep changing the baud rate on the fly (I don't want the scope to be "deaf" while it waits for the trigger, because the trigger may never come).
I know there are some POKE's for the 18X, so does anybody know an equivalent approach for the 28X1?
Thanks,
Wolfgang
But now to my question:
Since I'd like to be able to go to low samples rates as well, does anybody know how to slow down PWM on an 28X1? In particular on the "classic" PWM pin 1, because I'd like to reserve the 4 hardware PWM pins for other purposes (to run at a slower period, used for analog control of trigger threshold and the like). I'm running the 28X1 at 16MHz clock (to maximize the acquisition and transfer speed), so the slowest PWM is 16 kHz - which means I can't even look at a full 50 Hz (20ms) period because the 256 sample record spans only 16ms. One option would be of course to slow down the clock frequency (internal oscillator instead of external resonator), but that would affect the ability to receive full-speed RS-232 commands from the PC unless I keep changing the baud rate on the fly (I don't want the scope to be "deaf" while it waits for the trigger, because the trigger may never come).
I know there are some POKE's for the 18X, so does anybody know an equivalent approach for the 28X1?
Thanks,
Wolfgang