The content of this topic has been archived on 2 Apr 2018. There are no obvious gaps in this topic, but there may still be some posts missing at the end.
Hi all,
I've seen a few guides for adding JTAG capabilities using a CA-42/DKU-5 cable, and I was wondering if it would be wise to add an external USB port connected to the JTAG for this sort of thing.
I suppose it could get confused for a proper USB port... what do you guys think?
No, the JTAG interface uses 4 signals called TDI, TDO, TMS and TCK and also signals to control the target reset lines. I don't think is possible to handle by cheap TTL-Serial-USB cables.
If I'm wrong and it's possible: Please share that guides!
Hi thirdwheel, it is possible to use a usb plug for convenience. I had the same idea for my Speedtouch 7802l, and it seemed to work for a 30cm cable. however, if someone gets confused about the additional usb port, the JTAG does only have +3.3 Volts, which is fairly 2Volts below USB currence. so as long as you put the data lines in the middle and take care that any line carrying current is on the outer lines, there shouldnt be a problem. however, found that using a connecting plug(hope this word exists the way leo-online tells me it does) and old motherboard-connectors is a more convenient solution, easier to solder and the resulting cable can be used for AVM JTAG which is quite useful as more than 50% of the used routers here in Germany are made by AVM
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