Error: No STM32 target found!

[markpow]

I think it is the most popular topic among STM32 programmers who use ST-LINK V2 programming devices.

I have two devices: one is the Lora E5 MIni, and the second is the Lora E5Dev board. Both respond to the AT commands, so I expect they are healthy.

A few days ago, I could access these devices and see their memory. Today, I can't, and I don't know why.

I connected the programmer to the dev board as needed, and I can't connect to this device.

I tried to change settings as the other programmers suggested to achieve connection to such devices but without any success. Programming STM32 controllers using ST-LINK V2 is a kind of magic. It's a horror for me. I can't program my devices.

I upgraded firmware versions several times without any changes.

From the ST-LINK, it looks as expected, I think:

As I wrote above, changes of modes and reset modes gave no change.

So, what is wrong? ST-LINK answers on connection, but why it doesn't see devices connected to it?

[Tesla DeLorean]

Did you switch the colours around? I'm seeing GREEN into PIN 1, on your Target PURPLE is 3V3, GREEN is SWCLK, ORANGE is GND

On the gray cable I'm seeing ORANGE into PIN 2

The connector/keying of the cable is mirroring that of the PCB pins

[markpow]

Is it right?

From the left:
VCC (1), DIO(7), CLK(9), TST(15), GND (20)

[markpow]

1 VCC, 7 DIO, 9  CLK, 15 RST, 20 GND

[markpow]

[markpow]

I there are the right connections now, it simply doesn't work:

I'm going to sleep. Thanks @Tesla DeLorean .

[Tesla DeLorean]

How are you powering the board?

The Pin 1/2 are an input of VTarget to match the voltage via buffering.

The STM32 Cube Programmer tells you the measured voltage, as 0.04V it should be the 3.3V there.

You can power via your USB connection.

You can pull 3.3V from Pin 19 of the ST-LINK.

Other than that, does look correct

If you had broken the board earlier, it likely won't connect now.

[markpow]

---

@Tesla DeLorean wrote:

How are you powering the board?

---

I didn't need an additional power supply when I programmed the Lora E5 Mini. I'm trying to download a new software version for such a device. If I connect this device director to USB (without Link-St V2), I can observe what sends some messages to UART, concluding that it isn't destroyed. So, the old version of the software on this device simply works.

I need to download new software for this device, but I can't, and I don't know why.

[TDK]

You need to power the chip. The ST-Link/V2 programmer does not provide power.

[markpow]

What a *** thing!

I decided to return to ST-LINK 2 Mini from WaveShare. I made my last programming on the Lora device mentioned above.

@Tesla DeLorean asked me if I powered supply this device during programming. I answered that I never didn't, but I could program Lora devices this way.

But I tried to add a power supply by USB and use the USB hub for Stt-Link (one for both). 

And surprise! STM32CubeProgrammer saw the Lora device!

Okay, so I removed the power supply via the USB and transferred it from St-Link Min directly to the Lora device. Oh! It still works!

Finally, I attached the St-Link Mini directly to the computer's USB port (without a SUB hub). Oh! It still works!

What changed?

For the first case, the target voltage changed from 3.24V to 3.26.

For the second case, the target device was 3.25V.

For the third case, the target voltage was 3.27V.

It seems that STM32CubeProgrammer doesn't accept a target voltage lower than 3.25V. 

Hello, STM32CubeProgrammer team. Would you consider changing the message displayed by this tool when the target voltage is too low? The current message, "No STM32 device found... " is not adequate to the situation causing the problem.

But, any ideas about what happened? Where was that 0.03-0.04V?

I started this thread by stating that programming STM32 devices using ST-LINK V2 is a kind of magic, and it's really magic.

Many thanks to all of you who participated in this thread. Thank you for your help, support, and patience.

PS. I will return to the seller ST-LINK V2 from STM32 because this one behaves unexpectedly.

[markpow]

@TDK No, ST-LINK V2 Mini from WaveShare has its power supply to the device, look:

It also works with or without giving the power supply directly from the USB.

The same was true for the former ST-LINK V2 ones from STM32, except for this one, which I mentioned in this thread.