[Youtube] How to make BK7231 development board - NodeMCU conversion - soldering guide, hot air, SMD

On ali you can buy an inexpensive board that has everything except the ESP system. It makes no sense to destroy NodeMCU.

Great idea! I was not aware that there is a relatively cheap board for this pad format and without a soldered module, although in retrospect it seems obvious.

However, I would not be afraid of the "destruction" itself, because the ESP can go to the place of the desoldered WB3S / CB3S and there is a wolf full and a whole sheep, while the @khoam solution has another great advantage - no need to desolder with hot air ESP.

Conversion is done and ready to test on a new driver

Good job with conversion. Which soldering station did you use?

Btw, from a brief glance, it looks like the TM1638 on your photo may be very similar to gn6932 and also to TM1637. We'll see how it goes.

From 1.17.53 build, you can switch logging UART via the example below:

Yes, setting UART1 as log port (instead of UART2) will help on this board a lot, because UART1 has the CH340 hooked up (and is also used for programming), while, on the other hand, the default UART2 would require user to connect separate UART to USB converter, just to get log.

Worth pointing out default speed is 115200 for UART1.

my work in progress



I've butchered this device for its CB3S https://www.elektroda.com/rtvforum/topic4027954.html#20904497

I kind of hate the battery powered deep sleep devices, so it's no loss. I'd hope to solder the ESP onto it though to see what Tasmota is like on battery.

Not many of the CB3S pins were soldered so this was relatively easy with some extra pb solder, flux and braid. I was switching from side to side quite quickly but also inching it upwards from the top. Luckily I did not break any pads.

I don't have a heat gun, so the NodeMCU is going to be a challenge. All pins on all sides are soldered 🥵

Heat gun is there a must have. Maybe you could try to use a high power soldering iron and form a U shape with a thick wire that will heat all pads at once but I am not sure if it will have enough heating capacity for it.

Very interesting idea! Or I have two soldering irons, one is old and in my recycling bag, but it could be brought back to life for some double-iron multi sided action.

Added after 8 [hours] 11 [minutes]:

>>20550752
Oh! Or get this. Not as much fun though

It didn't go too badly. Fairly smooth until the very end. The bent soldering iron to cover two corners wasn't a success - the original tip was too fat and the bend too curved to be effective. Nails and other thinner tips tried wouldn't get hot enough to melt the solder. Success was with holding the old soldering iron along the short bottom edge and using the quick-move trick on the other two sides, each with long pb solder sausage covering pins.


The hooked solder was pulling the module forward so when it finally freed it shot across the desk.

These were pads before cleanup after module came off


Then clean-up. Yes, I damaged the trace of 3V while braiding! 😭




The copper only looked exposed so I proceeded to align and solder a corner of the CB3S module. Yes, I should have checked continuity to 3.3v.



then other pads


Unfortunately that 3.3V pad was more damaged than I thought, there was no continuity between the AMS117 and of course the module was not powering. I wasn't in the mood to desolder to investigate, so here's a working bodge



80% happy with it. I just need to test GPIOs next. It came up with the OBK config of previous device but when flashed to latest OBK using OTA it did not reappear. I reflashed erased/redid RF partition but ultimately ended up going back to the original device fw then OBK again. No problem, I guess something was a little unhappy with all the changes. It's nice to have a BK board with soldered RST button and USB-TTL in such close proximity - Easy Flasher connected at max baud and flashed very quickly. Good to know a hot air gun isn't the only option to remove 3-sided modules.



autoexec is as above

decent outcome. all of the normal/standard GPIOs work fine. assume a couple are default pull-high because the LEDs come on as soon as the board is powered. one LED is duller than the rest - S3/P20/SCK - I'm guessing it has a (different?) internal resistor to the others, or just has one. I can't find the right bit in a datasheet yet.

That's an interesting finding. I'd first double check, maybe there is an extra resistor on the board or something. Also I'd just swap in place two of the LEDs just to be sure it's not a faulty LED.

You can drive even more LEDs with OBK if you use ShiftRegister

>>20550752

yes. these are cool

So, do they work good for BK7231? How do you do power cycle there - CEN?

i've not got a BK module loose to try, but it has a reset button (bottom right in my pic) the same as other dev boards. I have started flash dump in Easy Flasher using this button. I've only tested RX/TX with this but I see no reason why the other pins won't be fine too.

Good to know that at least these modules, and probably more, can be used in the ESP-12 half of this one board alone

BT3L, CB3S, CB3L, CR3L, C-8138, ESP-12, FL_M93_V1, MRE3S, MWA04, MWA6S, T103, TYWE3L, TYWE3S, XR3, WB3, WB3L, WB3N, WB3R, WB3S, WB8, WR3, WR3E, WR3L, WR3N, ZS3L, HLK-B30, ESP32-C3

I got it for when these LN882H modules arrive https://www.elektroda.com/rtvforum/topic4023264.html#21024176

Added after 43 [seconds]:

divadiow wrote:

i've not got a BK module loose to try

actually not strictly true. HLK-B30 is Beken 🙄. I don't have a regular BK module like CB3S loose

Added after 13 [minutes]:

@p.kaczmarek2 get one or two!

can someone please check continuity from P20 on the CB3S to S3 on the nodeMCU if they've done the transplant.

mine maps to SK pin not S3 as shown on the diagram in first post





also P21 goes to S3. I am detecting an I2C device successfully using S3 and SK.



Info:I2C:Address 0x77 (dec 119)

@divadiow

S3 -> P21
SC -> P23
SK -> P20

thanks!

grr

wish I'd double-checked diagram was correct ages ago.

Ah, so there was a mistake in the diagram? I will update it in a moment. This may explain why your BMP280 was not working (or which chip was it?), @divadiow

p.kaczmarek2 wrote:

This may explain why your BMP280 was not working (or which chip was it?)

BMP280/AHT20, yes. But I did try SDA2 on BK and was getting i2c address return. I have since tested with S3/SK and still the same. My BMP280 (no AHT) should arrive this afternoon so I'll know for sure.

Added after 37 [seconds]:

I was also trying with BL602 PR with BMP280 driver

Ok, can you check, is this diagram better?

hmmm. I think this is closer

So S0 is not connected?

oh no. I've fallen victim to reversed and non-reversed references. ignore me. I'll check again

Added after 9 [minutes]:

OK.

that last image is good/final I believe?

Added after 16 [minutes]:

p.kaczmarek2 wrote:

So, do they work good for BK7231? How do you do power cycle there - CEN?

yes, this is an issue for me with MQ-12F. I've been unplugging board to power off but I guess CEN is an option. maybe some extra push button to ground cen could be fit in somewhere

the other drawback of those ESP universal boards of course is the bottom row of pads don't trace anywhere.

These are perhaps a nicer option. they seem sturdier anyway. I haven't used this one yet


Added after 6 [minutes]:

https://www.aliexpress.com/item/1005005850152605.html

I have split BK7238 discussion to:
NiceMCU XH-WB3S Flashing, testing, pinout, development

Today my WEMOS W1F1 D1 (with ESP8266 module) arrived (along with BK7238 NiceMCU).

I wonder if it would make sense to convert D1 to BK7231? Then we could test Arduino shields with it...

I don't even know what Arduino Shields are. Googling time!