ST-Link V2 Cannot find CW-Lite target

Hi all,

I have soldering the pins of JTAG on ChipWhisperer as the picture shows. However, after I try to connect the pins to the corresponding ones on the debugger. The debugger cannot find the device. What mistake did I make? Shall I provide an additional power to target board as well?

The first thing to check - does ST/Link V2 need the “TVCC” (target vcc) power? If it’s a “real” ST-Link/V2 it might -I can’t remember if it uses it or not. What does the error message say? You can just connect the TVCC line from the ST/LinkV2 to the +3.3V pins up at the top of the target section.

You can try SWD mode as well, which only needs TMS & TCK connected (they map to SWDIO & SWCLK). The ST-Link/V2 should work with either JTAG or SWD, but SWD uses less wires so if there was a wiring/soldering issue less to go wrong!

Also check the JTAG/SWD frequency. You’ll need to turn it down - try like 250kHz to start (or anywhere in 50kHz to 500 kHz range, I forget what the ST-Link/V2 supports). The lack of decoupling caps on the target tend to mean the higher frequencies won’t work as well (you can try increasing it once you get a successful connection).

Finally - it may need the reset pin as well (nRST, not the TRS pin on the header with the other JTAG signals). You’ll need power to the target supplied via the ChipWhisperer (I assume the ChipWhisperer is plugged into USB?). I don’t think the device needs a clock by default for JTAG/SWD to work.

[EDIT - edited for clarity]

Hi, thanks for your reply.

I did not connect the TVCC pin. So where is the vcc power pin on the target board? There is no error message because the dubugger just cannot access the target

Every CW-lite should come with one of these stickers, which corresponds to the pair of unpopulated 20-pin headers on your CW-lite:

3.3V is circled here:

Hi, thanks for your answer!

So essentially, I should connect this VCC pin to the STM Debugger, right?

That’s what Colin suggested above. (I don’t have an ST-link myself to verify.)

Lost the thread sorry! Yes exactly. FYI on the target board portion there is a “3.3V header” as well that should also be the same voltage/connection from memory:

Hi, I just found the circle you marked is on the main board, not the one on the target board. Is it correct or are they the same pins? Also, there are two VPP pins on the JTAG interface, should both pins connect to the target?

There are many pins to access VPP, for convenience, and to allow for the various headers you may wish to connect to your CW-lite. It doesn’t matter which you use.

If in doubt, you can certainly ask here, but you may get faster answers by looking at the schematic, or with a multimeter.