Some Pictures of my JTAG Setup

Here are some pictures of my JTAG hardware setup for the NXT. The wiring is described in the NXT hardware document.

The NXT is connected to a Segger SAM-ICE JTAG interface which I got in a bundle with the AT91SAM7S-EK evaluation kit. The Segger unit is connected via USB to the host computer. At the moment I can use it only with the JFlash utility from Segger under MS-Windows.

As a JTAG connector I soldered an eight pin strip of 1.27mm pitch header into J17. It was rather difficult to solder due to the fine pitch and because I used lead-free solder. Also, to get at the board from below I had to unsolder the battery contacts, to be able to remove it from the battery compartment.

20 years ago soldering was easier, everything had 2.54mm pitch and we used lead solder.

The cable just connects the eight pins on the NXT JTAG connector with the corresponding pins on a standard 20-pin JTAG connector. It has only 16 wires, because the last four (17-20) are not used. The NXT prototype has the necessary pull-up resistors, but they could be missing in the final version, in that case they need to be added to the cable.

The cable in front of the JTAG connector is for the speaker. While I examined the NXT the original wires broke off after a while, since they were were very short and rather stiff. To repair it I soldered in a longer cable with a plug also made from header strip, so now I can remove the LCD+buttons+speaker assembly completely.