Template info for merkury MI-WW119-199W

[dac2020]

https://templates.blakadder.com/merkury_MI-WW119-199W.html

VCC and ground available on opposite sides of shorter segment of module sticking through main board when attached. VCC is the wider solder joint and ground is the 1st pad on opposite side. TX and RX available on top edge of module closest pins to the antenna. GND and D0 are available opposite end of top edge, last pad and 4th pad.

Has anyone flashed this using serial. Can you share a bit of info on what some of this means.
VCC, is it needed or is ground and TX and RX only needed?

[rebel7580]

You need VCC to power up the device with an external DC power source. DO NOT plug this into the mains AC while your flashing it!!

[dac2020]

Hi,

Yes, that makes sense. It's what I thought but wasn't sure.

I guess VCC=5vdc+ and GND=5vdc- and TX to TX and RX to RX as usual.
Sometimes GND is also needed for serial but most times not from the few things I've done so far at least.

Am I correct to assume this or there are variations?

[sfromis]

GND is absolutely always needed.

[dac2020]

Got it. Thank you.

[dac2020]

Oh, one more thing. Is there a standard baud and flow control on all these kinds of chips?

[sfromis]

In a broad perspective, no. But 115200 is very commonly working (including with ESP8266 and ESP32), with 9600 not too rare. Flow control is "usually" not used, just simple UART serial.

(Some terminal programs can autodetect bit rate; while this sounds nice, it does carry the risk of confusion when other things does not work).

[dac2020]

Thanks. I'll note this too.

[dac2020]

Ok, first time ever doing this.
I soldered pins to the tiny SOC. I have power and RX/TX/GND connected and the device has green LED.
At either 9600 or 115200, there is no output what so ever.
I assume I should be seeing something.

[sfromis]

You can't bank on that, unless you know the device is in a situation where you should expect it to send something. Note that you connect tx/transmit on one end to rx/receive on the other end, not straight.

[dac2020]

Terminal TX is connected to RX and RX to TX, GND to GND.

[dac2020]

The device is fully pulled out of the plug.

[dac2020]

What does it mean I can't bank on that? How do I flash the device if I don't get any output from it?

[sfromis]

I already explained "can't bank on that":

unless you know the device is in a situation where you should expect it to send something

Point being that devices cannot be expected to send continuously, but only in certain situations. ESP8266 will send briefly after boot, after that everything is up to the firmware in use. I've seen some firmwares being chatty on serial during operation, but not as a general expectation.

What I usually do is to hookup my wiring as I expect to to be correct, and verify by running esptool.py with flash_id after having booted with gpio0 low during power up (or run whatever other flashing tool). If that works, success, if not, start looking.

[dac2020]

I read what you said and understood.
The laptop Im using to test is Windows so limited in tools. I'll have to pull out the Linux one next so I have more tools.
I'm not getting a single character out of this board. It does have a small switch mounted directly onto it, presumably to flash or reset.

What I usually do is to hookup my wiring as I expect to to be correct, and verify by running esptool.py with flash_id after having booted with gpio0 low during power up (or run whatever other flashing tool). If that works, success, if not, start looking.

Over the head of someone totally new to this :).
The esptool.py is something I don't know anything about so would have to look into this now.
Maybe this is more than I can handle then.

[sfromis]

When things does not work, triple-check your wiring and power supply situation. Make no assumptions about anything being right already. Do not ignore the part of power supply status, many USB/serial adapters have unsuitably low ability to deliver 3.3V power.

[dac2020]

I've checked and checked and solder, etc all are fine. How long does it take to boot? Maybe I'm not holding it long enough.

[dac2020]

This is what I'm using which provides 3.3v.

https://www.tradeling.com/ae-en/product-details/dsd-tech-usb-to-ttl-serial-adapter-clear-22-x-08-x-01inch-sh-u09c-624fde9b308af9001bbf98cf-5e495521f60e52001b9c7631

[rebel7580]

I'm not 100% familiar with that flasher, but I dont see a discrete 5->3.3v regulator, so I'm assuming that 3.3v output is coming from the built-in 3.3v reg in the FT232 chip, which is only rated for 50ma MAX. Not enough to power the device IMHO. Better to have an external 3.3 supply.

[dac2020]

I don't have one and I've tried two devices.
It's time to give up. I think I'm done with the hardware hacking at this level as it's too time consuming.
Much of my time has been spent trying to find clips and ways to hold these tiny things and I would have to keep ordering stuff to do this work regularly.

I'll try again when I have some time but for now, I'll start looking for hardware that's ready to go or easier to convert.

Thanks for all the help.