Can't connect to STM8L052C6

[CDarw.1]

Hi,

I'm attempting to connect to STM8L052C6 with ST-link and receiving an error, "Cannot communicate with the device !"

I've read every forum post on google related to the issue and tried just about everything to connect.

Finally I found in the manual for SWIM entry sequence in reference to activation timing to make SWIM active the pin must be forced low during 16µs, next a sequence of four pulses at 1kHz (1ms), followed by four pulses at 2 kHz (500µs)

When I checked the pulses I found the initial low is 1.317ms, followed by four pulses of 1.334 ms, then four pulses of 0.667 ms

Could this timing be the issue why SWIM is not initiating?

[Peter BENSCH]

This timing of the entry sequence is the correct one. You will find the description in UM0470, section 3.2, which says e.g.:

The SWIM entry sequence is: four pulses at 1 kHz followed by four pulses at 2 kHz. The frequency ratio is detected and allows the SWIM entry. The ratio can be easily detected regardless of the internal LSI frequency value.

You've measured 1.334ms/0.667ms, which matches perfectly the given ration 2:1.

But what about the expected response where the HSI should have been turned on (right part of the diagram of fig 4)?

[CDarw.1]

Hi Peter, thanks for the response. The pin goes drops quickly four times, and this happens with or without the chip connected.

[Peter BENSCH]

It looks like the STM8 isn't responding with the correct pattern. Do you also use pin 1 for other functions on your board?

[CDarw.1]

The STM8 is not responding at all, that pattern happens regardless of the chip connected or not.

pin 1 is not connected to anything else, only the programmer. NRST connected to the programmer with a capacitor to ground

It's my understanding that when achieving a reset condition the program is not run, so SWIM cannot be disabled.

One thing I've noticed after launching STVP I can attempt to read the chip 1 time, then Reset is held low until either the STLink v2 USB is disconnected/reconnected OR exiting STVP and relaunching. Is this normal behavior?

[Peter BENSCH]

Besides debugging: does the application still work normally with the STM8?

You are right, SWIM will be usable when reset (and power supply) is activated, so it looks like a faulty STM8. Do you have the chance to test it with other systems too?

[CDarw.1 · Accepted solution]

Thanks for your responses Peter.

I resolved the issue by buying a new genuine ST-Link V2 and it worked like a dream. Something's wrong with my old one.

Figured I'd post the solution in case someone else has the same issues and stumbles on this. I was going crazy trying to connect to the board, literally trying everything thinking I was doing something wrong.. browsing every forum including the Russian ones - and I don't speak Russian!

[Peter BENSCH]

Thank you for updating the thread!

When your question is answered, please close this topic by choosing Select as Best.

/Peter