| Products > Test Equipment |
| Picoscope Hack |
| << < (3/18) > >> |
| _Wim_:
--- Quote from: voltsandjolts on November 26, 2022, 02:02:44 pm ---Nice! Dave did a teardown of this scope a few years back, but didn't open up the front end cans. youtu.be/TM7HGFOc74M?t=351 --- End quote --- Thanks. I watched that one. It is also the version with the protocol analyzer, and hence has a different board layout. It does however not have any unpopulated chips in contrast to mine, so those unpopulated sections will probably be the culprit for some of the remaining "issues". |
| voltsandjolts:
Did you try figuring out the checksum algorithm at all? The sigrok page you pointed to hints at its workings: --- Quote --- There is a checksum, but is very weak and overly complicated. The last two bytes contain the number of iterations that have to be done to a 14 bit LFSR to get a value that equals the sum of the preceding data when interpreted as signed bytes. The weakness comes from their method of reducing the sum to 14 bits: During summing they reset the intermediate value to zero as soon as it uses more than 14 bits. As the bytes added are signed, this happens very often. --- End quote --- Not sure how they worked that out. Don't think I've never seen LFSR used as a checksum method...ahh, well I suppose crc is an LFSR method. There is another picotech device that interests me but the checksum there is a PITA. It might be the same as this one. |
| _Wim_:
--- Quote from: voltsandjolts on November 26, 2022, 03:44:48 pm ---Did you try figuring out the checksum algorithm at all? --- End quote --- No, I did not. As the Sigrok paged showed bytes were summed and the checksum was just the position in the LFSR series that matches the sum, I just ensured the sum would not change by altering the serial number... I briefly thought about programming a generator in C#, but as my trick appeared to work, I did not invest any additional time in this. --- Quote from: voltsandjolts on November 26, 2022, 03:44:48 pm ---Not sure how they worked that out. Don't think I've never seen LFSR used as a checksum method...ahh, well I suppose crc is an LFSR method. --- End quote --- I have also no idea how they found that out, that would have been certainly far beyond my skills! |
| _Wim_:
To fix the memory, I would need to change the memory chip which I consider too risky. My board has a D9MNJ Micron Technologie (DDR3 SDRAM 1G-Bit 64Mx16), so that would mean max 128M samples @8bit, and I suspect that in 12bit mode they just half the amount of samples and leave those 4-bits unused. Remark: the 5444B from Dave's review had a D9SHD (256Mx16). This explains why I start to see glitches going above 100MS, and no software hack will be able to fix this... |
| _Wim_:
Rise time measurements (which confirms the 200Mhz bandwidth) |
| Navigation |
| Message Index |
| Next page |
| Previous page |