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Home / MISC Areas / Mattel JuiceBox JTAG Connections Questions regarding connection of JTAG hardware to the Juicebox

JTAG Connections (modified 0 times) DavidM348 Profile I finally got brave enough to get out the soldering iron and start making the JTAG connections, but I need some clarification. I am very ignorant when it comes to the hardware stuff, so please excuse the stupid questions! I have the Olimex ARM-JTAG wiggler clone - here is the top connector ->www.olimex.com/dev/images/arm-jtag-layout.gif Based on the pictures on the JuiceBoxJTAG section, there are six pads identified on the Juicebox(CKOUT, TDI, TMS, TCK, nTRST, and TDO), but it looks like only four are being used. I have read on this board that it is probably best not to connect nTRST, as this may cause some problems. Based on my ARM-JTAG cable, where would I connect the pad labeled CKOUT? Also (now this is probably the stupid part), are these the ONLY connections to be made to the Juicebox, or do I need to connect some others (like 3.3 volt source- Vcc, and ground)? If so, what are the best points on the Juicebox to connect for these? Thanks for the help! -David 11-15-2006 16:03:06

RE:JTAG Connections (modified 1 times) jbfan Profile Based on my ARM-JTAG cable, where would I connect the pad labeled CKOUT? According to the S3C44B0X user manual CLKOUT has nothing to do with JTAG, not sure why it is labeled with the JTAG signals. So don't connect it Also (now this is probably the stupid part), are these the ONLY connections to be made to the Juicebox, or do I need to connect some others (like 3.3 volt source- Vcc, and ground)? If so, what are the best points on the Juicebox to connect for these? Yes, you need both 3.3V and ground (GND). GND goes to the GND pins on the ARM_JTAG cable, use an ohm meter to find one that is near the JTAG signals (the copper foil is soldered to GND). The only schematic for a "real" ARM target I have shows both pins 1 and 2 of the cable tied to 3.3V and pin 11 (RTCLK) connected to ground. Again use an ohm meter to find a nearby 3.3V point (there is a fat etch under the "[46] TDO" label (on the wiki) that I think is 3.3V). Hope this helps. -J 11-15-2006 19:44:51

RE:JTAG Connections (modified 0 times) DavidM348 Profile Thanks!! One more question: I've used my volt-meter and found a place on the Juicebox that gives 3.3 volts across TDI, TMS, and TCK, but only ~0.24 across TDO. Would this point I've found be Vcc or GRND (I told you I was dumb when it comes to electronics!!)? This point also was soldered to the foil, so from your last message, this must be ground? How do I use my meter then to find Vcc? Am I looking for continuity across two points or a voltage? -David 11-15-2006 20:42:07

RE:JTAG Connections (modified 0 times) jbfan Profile This point also was soldered to the foil, so from your last message, this must be ground? Yes, if it was soldered to the foil it is ground. Am I looking for continuity across two points or a voltage? Continuity. With power off, you should get about zero ohms (or the value that the meter reads when the two leads are touching) between any two points that are the same signal. You can test this by measuring two of the foil solder points to see what reading you get. Then go between foil and something else (TDI) to see what it looks like when the two points are not connected. A known 3.3V location is pin 1 of the slot connector. -J 11-16-2006 02:22:45

RE:JTAG Connections (modified 0 times) DavidM348 Profile Thanks again for the help! I found a pad labeled VDD that has continuity to pin 1 of the slot connector. It had more room to solder a connection so I used that. Haven't tested JTAG yet but it seems to work for the serial connection (well, sort of, but that's for a different topic!) -David 11-17-2006 19:57:34

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