Wednesday, 3 June 2015

Arduino Mega 2560 clone: Comparison to original and issues downloading sketches using Mac OS X

I recently purchased a clone Arduino mega 2560 from AliExpress. The clone cost less than a quarter of the official unit (including delivery). As such, the decision seemed like a no-brainer. However, I now realise you should not assume the clone will be identical to the original. 


Figure 1: Genuine Arduino Mega 2560

Figure 2: Clone Arduino Mega 2560

My first observation upon opening the package was that the build quality is not as good (refer to Figure 2). Some of the pin headers were quite bent and are shown above after I bent them back into place. This may have occurred during shipping. In addition, the underside of the board is a little untidy.

However, the most surprising observation occurred when I attempted to download a sketch to the Arduino; the connected computer was unable to find it. After reading through a few forums (the most useful forum post was http://forum.arduino.cc/index.php?topic=261375.0) I found that my issue was due to the USB controller on the clone board. 

In addition to differences in general build quality, the clones are also cheaper due to a different USB controller chip; the CH340G as opposed to an ATMega16U2 programmed as a USB-to-Serial converter on the original. If you suspect your board may be the same, you can confirm by checking if you can find a chip with CH340G printed on it (refer to Figure 3). 

Figure 3: CH340G chip on Clone Arduino Mega 2560


After finding this was the issue, the issue was resolved by following the steps outlined below:
  1. Download Mac drivers for CH340G from here (Non English site)
  2. Run the following command in Terminal: sudo nvram boot-args="kext-dev-mode=1”
  3. Restart system
Once installed, I was able to download sketches to the clone without issue.

NOTE: This may not be an issue if you are using an operating system other than Mac OS X (e.g. Microsoft Windows or Linux).

2 comments:

  1. Also, your CH340G cheap board has the RX1 and TX1 labels swapped. Looks like they made a mistake in labeling, which would cause somebody confusion when they get around to actually trying to use those pins for serial...

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  2. Oh god. I recently got same board, and it does not work. I mean I can see the chip and can do everything with it, except sketches does not work. I see lack of some components near USB connector, can you please measure them? I need R3, R4, R5 measurements. Not sure they are all resistors, so I would be glad if you can check if they are capacitors as well.

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