JTAG interface - Clock does not seems like a clock

[Shweta_sawant]

Dear Support team,

JTAG Clock output from USB Blaster Rev.C is not in periodic pattern, it seems it has two frequency contents 6MHz and 1.2MHz. Can you please let us know what may be the reason behind such a clock signal?

This is urgently required for the project. 

Thanking you in advance.

[FvM]

Hi,
what are you trying to achieve? USB Blaster or any other JTAG programmer isn't designed as a clock generator. It's sending JTAG commands and data to the connected JTAG chain and receiving responses. Nevertheless the behaviour can be explained:

The signal patterns you're seeing are related to different phases of JTAG communication. 

1. Selecting a specific scan chain and operation mode in JTAG TAP controller using TCK and TMS lines.
2. Sending and receiving scan chain data using TCK, TDO and TDI lines.

To control all JTAG lines (Phase 1), USB Blaster is using kind of Bit banging commands, one step per USB data byte, respectively slow

Sending and receiving scan chain data is using special commands to exchange a burst of up to 63 Bytes at maximal supported speed of 6 MHz.

Happy developing
Frank

[Fakhrul]

Hi Shweta_sawant,

I hope the comment by our community member FvM above has addressed your concern.

Thanks.

[Fakhrul]

As we do not receive any response from you to the previous notification provided. This thread will be transitioned to community support. If you have a new question, feel free to open a new thread to get the support from Intel experts. Otherwise, the community users will continue to help you on this thread. Thank you.

[Shweta_sawant]

Thankyou for your reply