Are the 'SparkFun Serial Basic Breakout - CH340G' and 'USB to TTL Serial Cable (5V VCC)' equivalent?

I have a [SparkFun Simultaneous RFID Reader - M6E Nano that I interface with a [SparkFun Serial Basic Breakout - CH340G (setup to use 5 volts logic) and everything works perfectly fine. If I leave things exactly the same and I only replace the [SparkFun Serial Basic Breakout - CH340G with the a [USB to TTL Serial Cable (5V VCC) things don’t work.

Why is that? Aren’t the [SparkFun Serial Basic Breakout - CH340G and [USB to TTL Serial Cable (5V VCC) supposed to be essentially the exact same thing?

it goes without saying that the [USB to TTL Serial Cable (5V VCC) is recognized by the computer just fine and there are no issues with drivers etc.](FTDI Cable 5V - DEV-09718 - SparkFun Electronics)](FTDI Cable 5V - DEV-09718 - SparkFun Electronics)](https://www.sparkfun.com/products/14050)](FTDI Cable 5V - DEV-09718 - SparkFun Electronics)](https://www.sparkfun.com/products/14050)](https://www.sparkfun.com/products/14050)](https://www.sparkfun.com/products/14066)

Looking at the schematics, it should be the same. The only point of concern is the inductor L1 in the power line. The Nano is using power bursts when activating the RX or TX power. Not sure how the LC filter : inductor L1 + C3 + C4 react on that. If you have to have an external power supply try to connect that directly to the Nano and see what happens.

Unfortunately, I don’t have a power supply at the moment, nor will I have one for a while so I am stuck with what I have.

A couple of things:

  1. I am not even able to make initial contact with the Nano. Never mind doing constant reads (I don’t get that far).

  2. Given that the Nano works with 3.3 Volts and I am feeding 5 Volts, wouldn’t that be more than enough to at the very least make the initial simple handshake?

  3. Both the Serial Basic Breakout and TTL cable are connected to the same USB port, I would assume that if one had a power issue the other would too. So I really don’t think this is a power issue.

  4. If I go to the device manager in Windows, the virtual COM port is setup to work at 9800 bits per seconds. Correct me if I am wrong but that seems to me like its ridiculously slow (compare to what is normally used nowadays). At those low speeds, would any filtering going on have that much of an effect?

Sorry if I misunderstood your reply, I don’t have access to the schematics and even if I did I would have no clue how to read them.

Thank you.

if you select the page on Sparkfun ( e.g. https://www.sparkfun.com/products/9718), click on documents. You get to more information including the schematics. The 5V should be enough for a standard handshake (before TX/RX). Does the power led turn on ?

The only other difference is the 100 ohm resistor serial to TX in the FTDI cable and 10K pull up. Not expecting that to be an issue, but you never know.

The Nano does power on (the led on the Nano turns on).

Hopefully the SparkFun folks will chime in with an absolute answer, I have spent waaaaay to much time dealing with the Nano and other TX/RX pins, at this point, my hope is for a clear and concise answer from SparkFun as to why this is not working.

Both are USB to serial converters. But chips are different, so are the driver software. SparkFun Serial Basic Breakout - CH340G features the CH340G chip. To use it, you must install CH340G driver: https://sparks.gogo.co.nz/ch340.html

FTDI Cable 5V has FT232 chip inside. It is equivalent to sparkfun’s FTDI Basic Breakout board. To use this cable you must install FTDI driver in your computer. https://ftdichip.com/drivers/

As stated on my original post, and I quote:

monore:
it goes without saying that the [USB to TTL Serial Cable (5V VCC) is recognized by the computer just fine and there are no issues with drivers etc.
[/quote]](FTDI Cable 5V - DEV-09718 - SparkFun Electronics)

Oh, sorry. That means either there is a hardware problem or something is missing in the application circuit. Have you tested the cable separately? I mean, you connect the cable with your computer. Then short the TX and Rx pins with a male-male jumper wire. Now, if you open the serial monitor and send a message, you will receive the same message. This will prove that the cable is good. Otherwise, it is a faulty product. Have you already performed this test? Thank you.

Yes, I have tested the cable independently and everything works fine. The issue appears to be related to the ‘SparkFun Simultaneous RFID Reader - M6E Nano’ specifically. Just waiting for SparkFun to respond and confirm if that is the case or not.

Thanks.

I don’t think the FTDI cable is able to deliver the current needed by the RFID reader you’re using.

The problem with that answer is that I am not doing any RFID reading, the cable fails while trying to do the basic initial handshake (the part where the ‘Universal Reader Assistant’ software tries to identify the Nano board).

If the cable was at the very least able to handle the initial interchange of data between the Nano board and the software (Universal Reader Assistant) to the point that its able to provide the software (Universal Reader Assistant) with the necessary information to recognize the Nano board but it failed (brownout) while doing actual RFID reading then yes, I may agree with that answer, but it does not even get that far.

In any event, the power point is moot since the cable still fails even if an external power source is provided (in this case the only power used by the cable is just RX/TX power - the VCC in the cable is disconnected).

Any other ideas?

Thanks.

If you want to send the cable back for testing we can take a look at it and see what the deal is. It seems like all of the troubleshooting tips have been exhausted at this point.

Just reply to the Email thread we have going that you would like to send the cable back and I can create a return ticket for you.