CH341A Serial Memory Programmer Power Supply Fix

[camber]

Good point. The datasheet is in Chinese but as far as I can tell there is no write protect pin.
I resoldered every joint. I measured every component and is OK. I will order another board.

[Roland_W]

Hi All,

I bought a black CH341A and made the modification to use it with 3.3V, and 5V signal. I add the goldpin to power supply selector 3.3V or 5V.


Below the SPI signal measure using the saleae.com logic analyser 3.3V interface
 Screenshot 2022-08-25 143137.jpg (206.61 kB. 1334x1092 - viewed 704 times.)

Below the SPI signal measure using the saleae.com logic analyser 5V interface
 Screenshot 2022-08-25 143314.jpg (138.45 kB. 1155x1060 - viewed 526 times.)

[Chamara Electronic]

I find the problem of some ic not responding

Error message is IC not responding

This is video i made about,

https://youtu.be/Ooe0mcnHb5M

[Georgdew]

Hello Roland_W . Some of my opinion,explaining from your picture which I have modified below..
It was unnecessary to cut the threshold from U1 to C1 Capacitor. You will use 3.3V and 5V on the same capacitor, you will have an unstable fluctuation.
3.3V and 5V have separate capacitors, that is C2 and C1..Which means that each capacitor has different ratings (its own ratings) for different Voltages...
See my Mod in the next comment..

[Georgdew]

My modification:

Tested and working properly..
1.Reading bios dump file
2.Deleting the bios chip dump file
3.Writing the bios dump file

[impetus_maximus]

was this mod ever really necessary? i purchased a KeeYees SOP8 SOIC8 Test Clip and CH341A USB Programmer recently. when not hooked to a chip, it has 5v on the data(?) line. after connecting it to a video card BIOS chip, the pins that were 5v now show 3.5v

so, was this a case of early version issue or was it one person checking the open voltage and everyone freaking out? 

[DavidAlfa]

You're forcing the pins to clamp the voltage coming from the ch341, it's up to you to "freak out" or take the risk.
But one day you might want to read some important memory and get a surprise.

[coromonadalix]

some infoes here

need registration i think  or password to unarchive them ?

https://4pda.to/forum/index.php?showtopic=884713&st=7440

neoprogrammer
https://forum.laboneinside.com/viewtopic.php?f=35&t=76

asprogrammer  i think replaced by neoprogrammer
https://github.com/nofeletru/UsbAsp-flash/releases

[impetus_maximus]

You're forcing the pins to clamp the voltage coming from the ch341, it's up to you to "freak out" or take the risk.
But one day you might want to read some important memory and get a surprise.

i see. it's my understanding the programmer limits the current. now i'm hoping to find scrapped chips to see if i can read, then possibly kill one with it. 

some infoes here

need registration i think  or password to unarchive them ?

https://4pda.to/forum/index.php?showtopic=884713&st=7440

neoprogrammer
https://forum.laboneinside.com/viewtopic.php?f=35&t=76

asprogrammer  i think replaced by neoprogrammer
https://github.com/nofeletru/UsbAsp-flash/releases

thanks

[DavidAlfa]

Killing chips is rare, but do you really want to take the risk?
Furthermore, the modification is really simple.

[impetus_maximus]

Killing chips is rare, but do you really want to take the risk?
Furthermore, the modification is really simple.

well i risked it, and was victorious. (this time)

[Ian.M]

Do you also boast about jaywalking on the freeway?

The only reasons *NOT* to do the mod are if you lack the skills to lift a SOIC pin and run some bodge-wires, or if it isn't your CH341A board.  Even the need to work with 5V memory isn't a reason not to, as the switchable version of the mod isn't much more expensive or difficult to do.

[Starfox]

Hi I´m new to this Forum and found the 3.3V Fix from here on Google.

So I have modded my CH341A Black Edition, because i want to Flash a Winbond Chip with 3.3V

Only to be sure i have attached a Picture. On the above Pins for 25xxx Chipsets i have now 7 Pins with 3.3V and one Pin with GND (see Picture)

Is this correct ?

Schematic shows 3 Pins are 3.3V original without the 3V Fix

Pin 11,12 and 7 has 3.3V original
Now i have additional 3.3V on Pins 5,6,9,10 (called MOSI, MISO, CS and CLK)
Pin 8 is GND

Only to be sure before i Frie my Bios Chip 

[Starfox]

This Voltages are correct i have attached in Picture post above.

Also a new CH341A don´t have to be modified, it switches automaticly to 3.3V when connect to Chip.

[uski]

I think the ACT pin should go low if the chip has enumerated correctly. I have no idea why they made the jumper thing on the side, but according to the chinglish datasheet I believe the ACT pin is just supposed to connect to cathode of an LED with a resistor. The pin already has a 2k2 resistor in series and pin "3" has no connection, but is right beside a power trace. Just add a solder bridge and LED...or check with a meter.

I was wondering too... I removed the jumper and realized the CH341A enumerates in serial port mode. With the jumper on, it enumerates as the programmer.

Upon further research I found this in the datasheet:

To avoid effect 2-wire
synchronous serial interface when using SCL and SDA to configure, the ACT# of CH341 is set to low-level
through 2KΩ resistance during configuration time. The CH341 is enforced as EPP/MEM parallel interface
and synchronous serial interface, it doesn’t detect outside configuration chip forwardly

The datasheet is a bit confusing. This double-function of the ACT# pin is only specified deep inside the datasheet and not where the ACT# pin is described. So that's why many people, including myself, are confused as to why this jumper was there.

[majkl21]

I just want to place here some different 3V3 fix which source I found after browsing with Google: https://github.com/OpenIPC/wiki/blob/master/en/hardware-programmer-ch341a-voltage-fix.md
It is nicer solution because you only need to cut part of 5V rail, add short wire between C4 and output of 3.3V stabilizer and connect rest of isolated 5V rail to 3.3V.
In the source there is slightly different PCB version but after measuring I found that it is quite similar. Modification was checked by programming Atmel 24C01 and Puya P25Q21U with CH341 / NeoProgrammer.
Shortly: Cut continuation of 5V rail on the bottom side of PCB (now it goes only to 3.3V stabilizer). On the top side connect now isolated 5V rail part with 3.3V supply via jumper between 3.3V and 5V. Finally connect pin 9 of CH341A equipped with C4 to 3.3V supply (as mentioned in datasheet for 3.3V).

[sir_cedric_lex]

I just want to place here some different 3V3 fix which source I found after browsing with Google: https://github.com/OpenIPC/wiki/blob/master/en/hardware-programmer-ch341a-voltage-fix.md
It is nicer solution because you only need to cut part of 5V rail, add short wire between C4 and output of 3.3V stabilizer and connect rest of isolated 5V rail to 3.3V.
In the source there is slightly different PCB version but after measuring I found that it is quite similar. Modification was checked by programming Atmel 24C01 and Puya P25Q21U with CH341 / NeoProgrammer.
Shortly: Cut continuation of 5V rail on the bottom side of PCB (now it goes only to 3.3V stabilizer). On the top side connect now isolated 5V rail part with 3.3V supply via jumper between 3.3V and 5V. Finally connect pin 9 of CH341A equipped with C4 to 3.3V supply (as mentioned in datasheet for 3.3V).

I just noticed in your second picture (IMG_3050.jpeg) that C5 is a zero ohm resistor and not a capacitor. This might be a factory fault. C5 should normally be the same as C6 with a value of ca. 20 pF since both (C5 and C6) are crystal load capacitors.

[sir_cedric_lex]

Has somebody here saved the second attachment named ch341aProB+.jpeg from Reply #34 in this tread?
It should be a larger version of the shown thumbnail with a size of 1618.03 kB and a resolution of 2557x3300.

Reason: Due to a bug, the download button downloads the third attachment (51.99 kB, 1270x738) instead.

This might be a shot in the dark but maybe somebody saved it earlier...

-> It looks like this, just larger

[Ian.M]

I just had a rummage through my old PC's temp folders and found this.  No promises that its the right file as this forum recompresses image uploads, but it certainly looks*very* similar.  I've also uploaded it zipped, so you can see the exact file I've got rather than the recompressed version.

[sir_cedric_lex]

I just had a rummage through my old PC's temp folders and found this.  No promises that its the right file as this forum recompresses image uploads, but it certainly looks*very* similar.  I've also uploaded it zipped, so you can see the exact file I've got rather than the recompressed version.

Indeed, the image looks almost identical. Thank you very much for all the effort Ian.M!

PS: I don't know if it's a problem on my side but I can't open the extracted file with any image viewer on my pc. It might have gotten corrupted before archiving but thankfully the other (recompressed) upload works fine!

[Ian.M]

Hmm.  Its a 2550 x 3300  px JPEG, progressive, quality: 72, subsampling ON (2x1), and I can open the freshly downloaded and decompressed (with IzArc) zipped file here in IrfanView with no problems.  However, none of Microsoft's Win10 image or photo viewers or editors can handle that, nor can Chromium based browsers.  Maybe that's why it went AWOL!