Passive probing of JTAG programming of a uC

  • Thread starter berkeman
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In summary, the old test fixture is failing with a new version of the PCBA, but the JTAG programming Pod that is available at the office is working fine. The device uC JTAG ID is wrong, but it is possible that some tiny misalignment of the pogo pins is causing the problem.
  • #1
berkeman
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I'm working on an old test fixture that uses JTAG to program a microcontroller (uC) and its Flash memory chip on production PC Board Assemblies. The programming works fine with an old version of the PCBAs, but for some reason it is failing with a new version of the PCBA that should have had no changes to the JTAG connections, uC or Flash memory chip circuitry.

I'd like to passively monitor the JTAG programming stream to compare the passing and failing datastreams. Does anybody know a good tool or Pod or other way to do this? I've used an old HP logic analyzer in the past to do such probing for short datastreams, but the serial-to-parallel conversion is a bit of a pain for a vanilla tool without some formatting capability.

The JTAG programming Pod I'm using is the TI MSP-FETU430IF (and the Gang programming equivalent), and the uC is the TI MSP430F5437A with external serial Flash memory. I do have a TotalPhase Beagle SCI/SPI Serial Analyzer Pod available, if there is some way to adapt it to JTAG...

Thanks for any ideas.

https://msharmavikram.files.wordpress.com/2012/03/msp-fet430uif.jpg
msp-fet430uif.jpg
 
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  • #2
berkeman said:
The programming works fine with an old version of the PCBAs, but for some reason it is failing with a new version of the PCBA that should have had no changes to the JTAG connections, uC or Flash memory chip circuitry.

Does it fail all attempts to program them? If so I'd want someone to check the PCB artwork for unintended changes in those areas.

In the distant past I've had issues with changes to decoupling capacitors affecting programming.
 
  • #3
I am able to program the new devices just fine at my desk using my TI programming Pod. But the programming fails in the Mfg Test Fixture with an error complaining that the device uC JTAG ID is wrong (which I know is not true from my testing at my desk). I suspect some tiny misalignment of the pogo pins in the fixture and the new layout, but visually the connections look good.
 
  • #6
I've used a Saleae for this. Their software is amazing. They have a bunch of protocols already but it is very easy to add your own as well.

https://support.saleae.com/hc/en-us/articles/208666936-Joint-Test-Action-Group-JTAG-
https://support.saleae.com/hc/en-us/sections/201990583-Supported-Protocols
https://www.saleae.com
 
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FAQ: Passive probing of JTAG programming of a uC

What is JTAG programming and why is it important?

JTAG (Joint Test Action Group) programming is a method used to access and configure electronic devices, such as microcontrollers, for testing and debugging purposes. It allows for direct communication with individual components on the device, making it an essential tool for hardware and software development.

What is passive probing and how does it work?

Passive probing is a non-intrusive method used to monitor the signals on a JTAG bus without modifying or affecting the device being tested. It involves using specialized equipment to intercept and decode the signals on the JTAG bus, providing insight into the device's behavior without interrupting its normal operation.

What are the benefits of using passive probing for JTAG programming?

Passive probing offers several advantages over other methods of JTAG programming, including its non-intrusive nature, which minimizes the risk of damaging the device. It also allows for real-time monitoring of the device's behavior, making it easier to identify and troubleshoot issues during development.

What types of devices can be programmed using passive probing of JTAG?

Passive probing can be used to program a wide range of electronic devices, including microcontrollers, processors, FPGA's, and more. As long as the device has a JTAG interface, it can be programmed using passive probing techniques.

Are there any limitations to passive probing of JTAG programming?

While passive probing is a useful tool for JTAG programming, it does have some limitations. It may not be suitable for devices with complex JTAG architectures, and some devices may require additional setup or modifications to enable passive probing. Additionally, passive probing can only be used for programming and monitoring, not for debugging or modifying the device's code.

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