search

iliasam / Laser_tape_reverse_engineering

Alternative firmware for a cheap X-40 laser tape measure
https://habrahabr.ru/post/327642
MIT License
121 stars 46 forks source link

B2A module #16

Closed epsi1on closed 1 month ago

epsi1on commented 1 month ago

Hello, I have a module marked as B2A as in image. in known modules it is noted that a model named MB2A is not supported with this firmware. but the B2A module's visuals is very similar to 85A module which is supported by the firmware. Here are B2A images:

1

2

and here is 85A and 85B modules: (link) The B2A have an extra chip regard to 85A which i think it contains accelerometer (to show angle relative to gravity).

Do you think it is supported? Thanks

iliasam commented 1 month ago

You can see from the description: https://github.com/iliasam/Laser_tape_reverse_engineering/wiki/Known-modules that B2A has STM32G03/04x MCU (I don't know real type). U85 modules have STM32F03x MCU. So current firmware is need to be ported. Firmware for U85 is written with SPL, while there is no SPL for STM32G.

epsi1on commented 1 month ago

Hello, and thanks for the reply. While there is no SPL for the STM32G, do you suggest that HAL library be used for porting the firmware? I'm very interested to port firmware.

iliasam commented 1 month ago

Yes.

epsi1on commented 1 month ago

Thanks for reply. Can this document be used for programming the B2A module?

I'm using such device for programming (seller claimed that it is not chip fake one, he said it have ID which i'm not sure what it is.)

image

iliasam commented 1 month ago

Maybe yes. I hope, you have seen this - " You programmer must have a special reset pin (cheap Chinese St-Link dongles don't have it)." You programmer don't have it.

You can try to use bootloader.

epsi1on commented 1 month ago

nothing special. ~Thanks for the reply.~ ~Can i create a backup of device firmware in order to be able to restore it?~ ~Also do you suggest me to get one of these programmers~ ~I have a USB to TTL too converter by the way.~ ~Thank you again~ ~i'm interested to get one for this and for future usages, unless it doesn't make any help for me now~

epsi1on commented 1 month ago

Hi, I've got one of these programmers image

First question is it intended that NRST pin on this programmer work?

I 've connected the module to programmer like this:

Connect "PWRON" line to VBAT line - to power on module.
You need to connect SWDIO, SWCLK, NRST, GND to your programmer (ST-Link for example).
Also it is recommended to connect VBAT to TVCC (target VCC) input pin if your programmer has it (like original St-Link).
Notice that NRST must be connected! You programmer must have a special reset pin (cheap Chinese St-Link dongles don't have it).
You need to select "Connect under Reset" and Reset mode: "Hardware Reset" in options of your programmer software.
This method is recommending if you are planning to change source code.

but i've got following error:

failed

would be thankfull if you give me some points on how to fix the problem

iliasam commented 1 month ago

Configuration of the CubeProgrammer utility is looking OK. Target Voltage = 2.9V is looking too small. How do you connected power from module to programmer? (How pin1 of the programmer is connected?) How you are powering your module? What is the voltage at si5351 (its pin1 is VDD)?

epsi1on commented 1 month ago

Thanks for the reply. I've did another test.

failed2

Here is how things are connected:

B2A STLINK
1-SWDIO 7-SWDIO
2-SWCLK 9-SWCLK
3-RX Not Connect
4-NRST 15-RESET
5-BOOT0 Not Connect
6-GND 4- GND
7-PWRON 1- VTREF
8-Vbat 1-VTREF

And here is what i do assume pinout of my stlink (according to utmel.com)

stlink

The voltage at pin1 (VDD) of si5351 is 3.26V

Thanks

epsi1on commented 1 month ago

Another odd thing is the laser diode on module is constantly ON (but seems not with full power) after i did connect module to STlink Thanks

iliasam commented 1 month ago

"How you are powering your module?" What is Vbat value? What was the original battery of your module?

Check this point - image If it is 3.3V, so this is MCU VDD, you can try to use is as source for programmer VTref.

epsi1on commented 1 month ago

Hi, Thanks for reply.

1

"How you are powering your module?"

Not sure, two pins on B2A module (7-PWRON and 8-Vbat) are connected to VTRef an nowhere else. no other batteries etc. 4Untitled

2

What is Vbat value?

You mean the voltage of VBat pin on module?

What was the original battery of your module?

Untitled2

A*uman (the t is replaced by *) 651720 3.7v 0.82Wh 2402

3Untitled file

3

Check this point - If it is 3.3V, so this is MCU VDD, you can try to use is as source for programmer VTref.

Multi meter said it is 3.25v, so i think it is 3.3v. but could you please give me some info on how can I connect it into VTref?

Thanks

iliasam commented 1 month ago

VTref of the st-link programmer is INPUT! it is power for internal programmer voltage-level converters. So you need to have external power source with V=3.7-4.2V. Maybe 3.3V will be suitable, but I'm not sure. It must be connected to Vbat and GND of the b2a module.

PWRON of b2a also must be connected to that power source. VTref is better to be connected to MCU VDD with 3.3V.

Looks like that now your module is powered by voltage leakage through data pins.

You can try co connect pins 1 and pin 19 of your programmer, and do not connect anything other to that pins, so programmer will have 3.3V for its internal voltage-level converters. https://i.sstatic.net/rIMNJ.jpg

epsi1on commented 1 month ago

Thanks for information, and sorry for bothering you.

i did some changes, now a 3.7v battery is also connected like this:

B2A STLINK
1-SWDIO 7-SWDIO
2-SWCLK 9-SWCLK
3-RX Not Connect
4-NRST 15-RESET
5-BOOT0 Not Connect
6-GND 4- GND
MCU VDD (solder new wire to the cap pin) Vtref
B2A Battery
6-GND GND
7-PWRON +3.7v
8-VBAT +3.7v

Voltage at VBATT and PWRON are 3.66v voltage at MCU VDD (and VTref pin on STLINK) is 3.26v a new wire from MCU VDD is soldered to capacitor and other end to vtref pin on STLink.

but still get message:

failed3
iliasam commented 1 month ago

"voltage at MCU VDD (and VTref pin on STLINK) is 3.26v" But utility is writing that voltage is 2.99-3.01V. This is strange for me.

epsi1on commented 1 month ago

Did a retry with boot0 and UART method, got this error: Can it be some sort of reverse engineering protection?

uart-faiiled
iliasam commented 1 month ago

I don't think so. Your MCU is silent. Looks like STM made changes at STM32G bootloader activation: https://community.st.com/t5/stm32-mcus-products/has-anyone-gotten-the-boot0-pin-to-work-on-an-stm32g071-solved/m-p/338772 https://electronics.stackexchange.com/questions/598336/stm32g030-boot0-pin-swclk Maybe connecting SWCLK to 3.3V can help, maybe not.

Is MCU of your module still working without connections, when LCD with keys connected?

epsi1on commented 1 month ago

hi

Is MCU of your module still working without connections, when LCD with keys connected?

Yes, when i remove programmer and connect battery and keypad to the module, it works just fine as before. Let me try to connect SWCLK to 3v3 and retry... Thanks for tips, i really appreciate it... Have a nice day

epsi1on commented 1 month ago

just another question which is not related to the µc, would be thankful if you clear me.

in this file, at the Laser Diode D3, have a question about voltage at it's anode. I think voltage at D3 anode is sin wave, but what is the min and max in volt scale? i think it should have offset from zero but not sure.

Thanks again

iliasam commented 1 month ago

" but what is the min and max in volt scale?" Sorry, but I can't say - I don't have a suitable oscilloscope when I was doing experiments with that module. Laser diode circuit is generating voltage offset - it is near 2V.

epsi1on commented 1 month ago

Lets close this issue for now. Thanks for all information.