Electronics > Repair
CH341A Serial Memory Programmer Power Supply Fix
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pupa:

--- Quote from: theIC on July 07, 2020, 12:17:15 am ---
--- Quote from: pupa on May 28, 2020, 12:19:40 am ---Ok. Herewith my mod to recover from disaster.

--- End quote ---
I created an account just to thank you all for the wonderful mod. From Chuck Nemeth's blog which lead me here to Pupa's fix.
I attempted to do the mod, and did not have the dexterity as some of you. I attempted to use some leftover ethernet cable strands and between the insulation burning away and also breaking pin 29 from the IC, I got the idea from pupa to grind away the area by pin 29 to expose some metal to resolder the wire. Anyway, it all worked.

--- End quote ---
Glad it worked for You. ;)
pupa:

--- Quote from: fulda on February 12, 2019, 12:38:16 pm ---
--- Quote from: johnmx on October 14, 2017, 12:29:37 pm ---All Vcc connections in the ZIF socket are 3.3V but the CH341A is powered at 5V.
So all I2C and SPI signals are 5V while the external memory is powered at 3.3V.
There are no limiting series resistors on those signals.

One simple solution to fix this issue is to simply bypass the 1117-3.3V regulator.
I can use the hot air station to remove the 1117 and then short-circuit the input with the output.

My question is, is it safe to just do the short-circuit without removing the 1117 linear regulator?

--- End quote ---

Hi,

The trick is, that you miss 2nd LDO, that is inside CH341A chip.
Check datasheet.

At end of chapter 5.2 硬件说明 (Hardware description) is stated:
CH341芯片支持5V电源电压或者3.3V 电源电压。当使用5V 工作电压时,CH341 芯片的VCC 引脚 输入外部5V 电源,并且V3 引脚应该外接容量为0.01uF~0.1uF 的电源退耦电容。当使用3.3V 工作
电压时,CH341 芯片的V3引脚应该与VCC引脚相连接,同时输入外部的3.3V电源,并且与CH341芯
片相连接的其它电路的工作电压不能超过3.3V。
It can be translated:
The CH341 chip supports a 5V supply voltage or a 3.3V supply voltage. When using a 5V supply voltage, the VCC pin of the CH341 chip inputs an external 5V power supply, and the V3 pin should be externally connected with a power supply decoupling capacitor of 0.01uF to 0.1uF. When working with 3.3V voltage, the V3 pin of the CH341 chip should be connected to the VCC pin, and an external 3.3V power supply is input, and the CH341 core is connected.
The operating voltage of other circuits connected to the chip cannot exceed 3.3V.

As far as I understand, that mean, that chip have internal 3.3V regulator and IO pins are NOT 5V tolerant. It mean, it always use 3V3 for communication with eeprom.

--- End quote ---

Maybe these videos will make it clear that without the recommended mods how casual use without consideration for proper voltage levels to the target bios/memory chips could lead to a disaster. It also shows actual voltage measurements, thus how to test and confirm the voltages for yourself for peace of mind. It also confirms how versatile this device is by showing how it can be modified by providing a simple modification to further extend its use.

Enjoy!

CH341 Programmer 3.3V Fix:



Modify the CH341A EEPROM Programmer (Black Edition) for 5V 93XXX & 95XXX Automotive Use:



pupa:

--- Quote from: pupa on May 28, 2020, 01:21:01 am ---
--- Quote from: davidm71 on November 11, 2017, 06:25:01 pm ---Ok. So then why did they put on the market a defective bios programmer?!

--- End quote ---

Did you see the price? Many people now owns and support the unit via research and new information and apps to write to EEProms and AVR's. There are a few projects already on the net with improved circuit and PCB designs for download. Soon it will be the de'facto standard for hobbyists.
EEProms is well supported through Flashrom  on Linux and on Windows there is a GUI app on the older release version.
AVR's are supported through a few programming apps for the hobbyist within limited support for the latest chips but then again there is MPlab for that in the meanwhile but at a cost in comparison.
Now I'm just waiting for AVRdude  to possibly revive, get updated and also support this programmer.

--- End quote ---

Just to confirm AVRDude 6.3 fully supports the CH341A programmer. Using the search program "Search  Everything" I searched for all instances of AVRDude.exe on my development system as many programs and IDE's use it, then renamed (i.e. backed up) the original files, then updated AVRDude.exe as well as AVRdude.conf with the updated AVRDude 6.3 files taken from http://forum.easyelectronics.ru/viewtopic.php?f=13&t=32626%D0%BD%D0%B0 (Use Google translate to read but take note that the download links only works from original Russian site). I also patched the Arduino AVRDude folder the same way thus  the Arduino IDE 1.8.12 now also it works well with the CH341A programmer.  :)

The AVRDude.conf file should contain the following information to be sure its working with the original WCH driver and port shown as "USB-EPP/I2C... CH341A" in device manager in windows 10.

programmer
  id    = "ch341a_bitbang_wch";
  desc  = "ch341a programmer (bitbang_wch)";
  type  = "ch341a_bitbang_wch";
  connection_type = usb;
  usbvid     = 0x1A86;
  #usbpid     = 0x5512;
  usbpid     = 0x5523;
  usbvendor  = "wch.cn";
  usbproduct = "CH341A";
;
jakeisprobably:
I got bored and retraced...
jakeisprobably:
I reworked the attached images above. I also uploaded a new version of the schematic in PDF on github. The dot pro files are included for kicad. I haven't bothered to make it pretty on github. The files are a bit of a mess as these are the result of creating the files on one computer and transferring them to another, doing a couple more edits, then making the git repository. On the bright side, I can confirm, all the files and libraries needed are included. I have also created a 1:1 reproduction of the programmer in PCBnew. Have fun.   
https://github.com/Upcycle-Electronics/CH341A-Pro
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