Me again, thanks for the answer. > >> There is no IC Datasheet to find anywhere using google. However I found some >> chinese document indexing website that had a reference to a document that I >> managed to translate to get the interesting info. > > Do you have a URL for that please? >
Sure. Good luck to use this crappy website… http://www.mianfeiwendang.com/doc/c2fdadc6a878f5c1871f2fff/1 <http://www.mianfeiwendang.com/doc/c2fdadc6a878f5c1871f2fff/1> > >> The protocol is a 15 bytes (!) continuous 2400 8N1 dataflow very close to >> the FS9721 data structure >> This protocol looks quite unique, I didn’t found anything about it on the >> web. >> The decoding table is the following : >> Note that the digit lettering this one (NB the sigrok wiki refers to a >> completely different lettering) > > The individual flags in bytes 0-12 (RS232, Auto, DC, etc.) are exactly > the same as in the FS9721, though apparently the order is inverted (bits > 3..0 instead of 0..3), assuming that's not just a typo in either our wiki > or the table above. > Right. I double checked and I’m pretty sure this table is the right one (I wrote it based on the data sheet and my own observations). > http://sigrok.org/wiki/Multimeter_ICs#Fortune_Semiconductor_FS9721_LP3 > > The LCD digit mapping might be different. Can you put the above table and > the digit-mapping in the wiki please (similar to the FS9721 docs above). > Oh, and an "lsusb -v" as well. I think the author of the wiki for the FS9721_LP3 entry used a "non-standard" way of naming each segment of the display. Looking at the data sheets, the protocol is the same, except the nibble order. > > > Please also upload a few photos (top/bottom, and PCB shots if possible) > to the wiki. Thanks! I already took them :-) > >> I guess that this enough to develop a new driver dtc0660 based on the FS9721. > > Probably, but let's clarify a few other point first, just in case. > > One thing to check is whether one of the other FS... ICs may have an > even more similar protocol. Doesn't look likely, though. I already checked this and can confirm that FS use a totally different protocol for their 6000 points series. I thoroughly checked that this 15bit protocol wasn’t used elsewhere and the only one I could find was a metrex (voltcraft) one that has nothing to do with mine. > > Another thing to check is the "lsusb -v" of the USB cable the DMM ships > with. We know about some cases where the cable actually alters the > protocol as transmitted by the (e.g. FS9721) multimeter IC, which might > or might not be an explanation of the differences to the FS9721. Bus 029 Device 002: ID 067b:2303 Prolific Technology, Inc. USB-Serial Controller Looks like a good old Prolific 2303 Serial to USB cable. > > It could of course also be the case that the DTM0660 just intentionally > emulates the FS9721 (or some other IC's) protocol, correctly or > incorrectly. > > The length of 15 bytes (instead of the FS9721's 14 bytes) is also > interesting, they probably just needed a few more flags and ran out > of space in the 14 existing bytes. > I agree, though there seems to exist an option (setting in EEPROM) to send the data in 14-byte form, if I correctly understood the chinese translation. > >> I’m ready to spend some time on it. Would somebody feel like helping me to >> help me find my way in the project structure and to kickstart me ? > > Probably best to join IRC for this, makes things a bit easier. But > here's the quick version: > > *If* there's a need for another parser, you'd create dtm0660.c in src/dmm, > and hook it up in src/hardware/serial-dmm/*. Search for fs9721 there to > find the places where the parsers are used. > Good. I’d need some input to test and debug the new driver as well, but let’s discuss this through IRC. > > Then you'd just add one DMM() entry there for the Velleman DVM4100 > referencing the parser etc. ... and to the Peaktech 3415 USB which looks rigorously like the same machine. http://www.peaktech.de/productdetail/kategorie/digital---handmultimeter/produkt/peaktech-3415-usb.815.html <http://www.peaktech.de/productdetail/kategorie/digital---handmultimeter/produkt/peaktech-3415-usb.815.html> Matthieu > > > Uwe. > -- > http://hermann-uwe.de | http://randomprojects.org | http://sigrok.org
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