SCANSTA112: TRSTb, TLR_TRST, TLR_TRST6

Shruti Malhotra

Part Number: SCANSTA112

Hi,

I am designing a board where I need to multiplex 32 JTAG devices(FPGAs). As per the plan the devices are divided it into 8 chains with 4 devices each. 7 chains are connected to each of the LSPs of the STA112 and for the remaining 1 chain, a separate JTAG programming connector will be used. STA112 will be in transparent stitcher mode.

I have the following questions related to the design:

1) What is the difference in the affect of TRSTb on STA112 and affect of RESET on STA112?

2) In transparent stitcher mode, does TRSTb reset the STA112 logic? Is there some way to mask it in this mode?

3) Can we use the TLR_TRST and TLR_TRST6 in transparent stitcher mode to drive the TRST of the unselected LSPs?

4) Is there a limit on the number of devices that can be connected to each LSP port? Can we connect 8 devices? If we could eliminate that one extra JTAG connector it would be great.

Shruti

over 5 years ago

0 Yaser Ibrahim over 5 years ago

TI__Genius 10250 points

Hello,

There is a document that gives some more details on these devices. I am attaching it here for you reference.

Regards,

YaserAN-1259 SCANSTA112 Designer's Reference-snla055h.pdf

0 Shruti Malhotra over 5 years ago in reply to Yaser Ibrahim

Prodigy 40 points

Hello,

The document answers the first 3 questions. Thanks for that.

Could you help answer the fourth question? Is it okay to connect 8 FPGAs on one LSP?

Shruti

0 Yaser Ibrahim over 5 years ago in reply to Shruti Malhotra

TI__Genius 10250 points

Hello,

I am not aware of a specific limit on number of devices on one LSP, so it is worth trying. The drive capability of the outputs from the LSP can drive so many inputs, but that depends on the input current the FPGAs draw. I suspect that is very low (several uA) and if that is the case, then from this perspective it shouldn't be a problem.

Regards,
Yaser

Interface

Interface forum

SCANSTA112: TRSTb, TLR_TRST, TLR_TRST6