Don Koch

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  1. Michael -- Thanks for responding. Above where I asked what would happen if I removed power, I was referring to removing USB-side power. In our fixture, connections are always present -- everything is under program control and we cannot require the personnel performing the test to plug and unplug cables during the test. How would the JTAG-HS3 behave if I never gave it USB-side power, and only have it power from the target? Would the USB interface still work, or does it need 5V to drive the USB port? From my black-box testing, when JTAG target power is present the HS3 stops drawing current from the USB port. For my test fixture use, I am thinking that I should have the test fixture power the HS3 with a controllable (on/off) supply (3.3V on the JTAG side). We can do this because the HS3 is not directly connected to the UUT. The USB power pin would always be disconnected. When we want to program the UUT we will turn on the HS3, download the JTAG data, and turn it off. Power cycle the UUT, and we are going. Does this sound like it would work?
  2. Starglow -- Like you, I found that there are no male 2mm ribbon cable connectors to use to connect to the HS3. I used a PCB mount Molex 87832-1420 connector. For another project, I came across this board, which is a pitch adapter: Due to their size, they are relatively inexpensive. The configuration on the right shows a pair of them ganged together to create a male to male 2mm adapter. The board design was published, allowing OshPark to sell them to whomever wants them. The through-hole 14-pin 2mm male connector is fairly easy to find (these are Sullins SBH21-NBPN-D07-ST-BK). After clamping the two boards together, pins from a standard 0.1" header were inserted, soldered, and trimmed off. Not real pretty, but it works. If you have the resources, you could simply make a small male-to-male board that is smaller. Again, I hope this helps. Don
  3. Starglow -- I had a similar problem. The ends of the Molex connectors are too close together to accept a normal 2mm ribbon connector. For the short term, you could saw the ends of the connector off with a razor saw. For the long term, we are using parts similar to 98424-G52-14LF from FCI. It should accept either a ribbon cable or the HS3. Specifically, we are successfully using an 98424-G52-18LF part on our board. We use an 18-pin ribbon cable to connect a "debugger board" that contains all of the circuits that we didn't have room for on our product board. The extra four pins are used for setting the Zynq boot mode, provide power to the debugger board, and control a debug LED. The HS3 may be plugged into the center 14-pins of the connector in this scheme. If you only add two additional pins, the alignment tab on the HS3 connector will not line up with the connector pins. The following describes our test fixture: One 14-pin male connector for the HS3 programmer One 18-pin male connector (center 14 pins tied to the connector above) An 18-pin ribbon cable (female on both ends) to connect the unit under test to the connector above. I hope this helps. will be plugged into the test fixture (14-pin male), be connected to an 18-pin male connector, jumpered over to the unit under test using an 18-pin ribbon cable (both ends female), and plugged into the unit under test. This is proven to work.
  4. I have a JTAG-HS3 programmer that is performing strangely. When powered, it seems excessively warm. I can use it to program my Zynq board if in JTAG boot mode, but it will not boot up unless I disconnect the programmer. I checked the reset line, and it is not being asserted by the programmer. I tried a different unit and it works fine. Is this a common failure mode? I will be embedding a JTAG-HS3 in my test fixture for the Zynq board. If I remove power to the programmer, will the JTAG signals be high impedance? Should I insert buffer gates on TMS, TCK, and TDI to isolate the unit under test from the programmer? Thanks for your help.