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20b:using_jtag

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20b:using_jtag [2008/08/02 19:48]
newell Adding example of slotted back for JTAG connector
20b:using_jtag [2008/08/02 21:20] (current)
newell Fixing typos, adding Mouser part number for suitable JTAG connector.
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 +To use a JTAG interface, you will need 3 items:
 +- a modified calculator
 +- a JTAG interface
 +- a program that can use the JTAG interface.
  
 +The calculator needs to be opened, and a JTAG header needs to be soldered. The JTAG header is a standard 16 pin Berg SMT header with 2.54mm spacing. I have a picture, but I do not know how to upload it, so if someone that know how that whole wiki knows, please drop me an email and I will send you the picture.
 +
 +The soldering job is easy, even for a SW engineer. You can use a simple $20 soldering iron from Radio shack if you do not have one (I use a gas powered one personally)..
 +
 +I advise that you make a hole at the bottom of the calculator in order to allow to close the calculator back up while still having access to the JTAG (here again, I have a picture)... the hole should cover the height of the recessed space at the bottom of the calculator back and be around 4.5cm wide.
 +
 +Then, install the JTAG drivers, connect the JTAG interface to the PC and the board and you are ready to rock and roll.
 +
 +I use the Atmel SAM-ICE JTAG (around $150 or so) available at Digikey or Mouser....
 +
 +For the PC side, I use the IAR tools, and I advise that you use them also as the demo projects given by HP are using them also.
 +
 +Compile the project, '​debug'​ and here you are!
 +
 +They are however restrictions. ​
 +- The debugger has only 2 breakpoints that you can use (because the ARM has only 2 hardware assisted breakpoints).
 +- Programming works much easier if you erase the flash first manually.
 +- The debugger does not work if and when the CPU goes in sleep or OFF mode. (This is why I always debug with the calculator in '​TestSystem'​ mode.)
 +
 +
 +(Here'​s what my JTAG slot looks like.  It's about 1.1" by 0.35"​. ​ Now that I've put it all back together, the JTAG IDC connector is just a little close, so I should have extended the slot down closer to the bottom rubber foot.  I tried to avoid digging too deep into the area where the back door latches engage. ​ The plastic is soft; I used a Dremel with a carbide burr and had no trouble at all.  --newell)
 +
 +{{20b:​jtag_slot.jpg}}
 +
 +(For the 16 pin JTAG connector, I used an FCI 95278-101A16LF from Mouser, part number 649-95278-101A16LF,​ $0.75/​each. ​ Before the connector
 +arrived, I was using 24" lengths of wirewrap wire soldered to the JTAG pads, and that worked fine, but it was a bit messy. ​ --newell)
20b/using_jtag.txt · Last modified: 2008/08/02 21:20 by newell