usb oscilloscope

wow, i've gotta try this. it gives you about 60hHz with almost nothing but a pic 18f and a usb port. i think i could do it without the serial bootloader, which makes it even simpler. sure, it's not the most powerful dso, but it's so simple and would help me make a better one if i wanted to. the biggest challenge would probably be software. the author wrote his scope code in visual basic. (!!?! well, i guess i can't complain.) so i'd have to reimplement. but it might be a good way for me to learn how to do usb data xfer in linux, anyway. and maybe i can make an inteface to comedi. i think that would let me use it with xoscope. neither looks like it's released a new version in a while, but i've tried xoscope before (with the soundcard oscope, heh) and it worked okay. i've also been thinking about how to do a cheap and easy high-speed dso. i think video capture adcs are the way to go, with data fed directly to 5-10ns sram. the TVP7001PZP, for example, can do up to 165MHz with a pll internally-multiplied clk for 3 syched channels. built-in scaling and offset, with i2c interface would make it easy to control with a usb pic. for triggers, maybe i could set voltages on dacs and use an opamp comparator with a latch so that the leisurely pic could stop the adc a given time after triggering. the position of the trigger time within the data window wouldn't be exact, but the trigger wouldn't need to be checked at the same speed as the adc. i think it could actually work, and i'm surprised i can't find anyone who's already done it. hmm, maybe that should tell me something.... well, i can't find any reports of failure, either. EDIT: there is an updated firmware version here that provides 5 analog and 8 digital inputs. i tried messing around with gpdasm and gpasm on the hexes, and the non-bootloader hexes produced by gpasm for the 18f458, 18f2550, and 18f4550 are identical. i think i will do the same thing with the superprobe and put a diode instead of a resistor on mclr. rb6 and rb7 will already have some leads for the digital io, so i just need to plug in to the +5 and gnd on the usb to program this thing with my serial programmer.