Programming directly from a CH340 USB Cable

Hello all,
I was wondering if it is possible to directly connect my Nano clones to a USB to Serial adapter. The interface does appear in the Arduino IDE and I think I've located the correct GND/RX/TX pins. The cable uses a ch340/341 chip and it seems to be the same chip that is on my Nano clones. I haven't gone as far as cracking the DB9 case open(where the chip resides) but by all estimations it at least appears to be the same.

The cable seems to be quite common. Both connectors are blue and the cable itself is clear and shows a silver colored shielding. I'm not sure who the manufacturer is as it was purchased from eBay. However, it does show up as "cu.wchusbserial3a230" in /dev. A picture of the cable can be seen at the link below. Again, it appears to be fairly common.

FTR I am working on OS X 10.11.6 but I also have a couple of linux boxes that I use where it appears as well. In each case though the "WinChipHead CH34x" driver needs to be installed. I initially installed this driver so I could communicate with my CH340 Nanos and luckily it also supported my serial cable.

My suspicion is that the serial cable is nothing more than the same chip found on my nanos with a DB9 port attached at one end and USB A cable at the other. Not knowing much about serial communications I'm assuming that the adapter won't act entirely like a true built-in DB9 serial port. The reason I bought it in the first place was to gain access to a used Dell managed switch which also required a "Null Modem" cable.

Ultimately I would like to use this cable to program some homemade barebones Arduinos(which I have not yet made) and also my single ESP201(ESP8266). I guess I'm just veing cheap and could spend 5 or 6 dollars on an FTDI board but I already have this and it would be great if I could get some more use out of it because I think its only been used twice now for the switch and is otherwise taking up space in my parts bin.


  • nothingClever

EDIT: MODS - If I have posted this in the wrong place please feel free to move it and if this is in fact the wrong spot you all have my apologies.

It looks like that cable is designed to emulate a PC serial port. The PC port uses RS232 logic levels which are NOT compatible with Arduino's TTL logic levels. You may be able to find TTL logic levels inside the 9-pin connector but you will have to break it open.

The UNO and Nano use the DTR signal to reset the board for an upload. If you only use RX, TX, and Ground you will probably have to manually reset the Arduino to initiate an upload. If you have an RX LED like on the UNO you can release the Reset button when the RX LED blinks.

Ok I think I'm understanding you. Previously when trying to connect to my ESP201 I used the TX/RX/GND from the cable a 3.3V from one of my nanos connected to usb... Does that sound like a possible solution? The IDE did claim to see the ESP under "Board Info"...

I'm obviously a bit unfamiliar with serial connections. I will be researching RS232 and TTL. If you are aware of any good resources please let me know.

TY for your reply.