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Today I got my clone Arduino and connected it to my real Arduino and they both work. (UPDATE: The Arduino noted as real Arduino probably also is not a real Arduino; however both work fine).

However, I see some differences and wonder if these are good or bad:

enter image description here

My questions

1) At number 1 there is on the clone arduino a 12 MHz oscillator? What does it do? And since there is also the regular 16 MHz oscillator I wonder why there are two.

2) At number 2 are 4 holes without any explanation. What is the function?

3) At 3 there are 12 holes (sorry that only 9 are visible, under the blue/black cable are 4 more holes with silver square around them.

4) At 4 there is a SCL and SDA which are used for SPI I think, but these are not on the original Arduino. But the original Arduino has 6 pins at the same location and 4 holes (where 2 of them are marked as JP2).

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  • 2
    Might need to check if your original arduino uno is not a counterfeit; arduino.cc/en/products/counterfeit
    – Mikael Patel
    Commented Mar 29, 2017 at 22:04
  • @MikaelPatel Probably the other one is not original either, since the text 'designed in Italy' is shown instead of 'made in italy'. But they both work :-)
    – Michel Keijzers
    Commented Mar 29, 2017 at 22:23
  • 1
    What is the number on the main chip on the black one?
    – Majenko
    Commented Mar 29, 2017 at 22:40
  • @Majenko first line: Delta-symbol (triangle) ATMEL, 2nd line: MEGA328P and 3th line: AU 1646
    – Michel Keijzers
    Commented Mar 29, 2017 at 22:43
  • 2
    Silk Screen. The white lettering and drawing on the board. The big giveaway is that they used a serif font for the URL. Serif fonts are common on Chinese boards. Arduino, and most "western" designers use a sans-serif font.
    – Majenko
    Commented Mar 29, 2017 at 22:51

1 Answer 1

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The best help is the schematics for the clone.

enter image description here

1) At number 1 there is on the clone arduino a 12 MHz oscillator? What does it do? And since there is also the regular 16 MHz oscillator I wonder why there are two.

Lower left on the schematics is the 12 MHz crystal. It is for the CH340G (USB-UART chip).

2) At number 2 are 4 holes without any explanation. What is the function?

Lower middle is the pins X1. They are extra signals from the USB-UART chip (CTS, DSR, R and DCD).

3) At 3 there are 12 holes (sorry that only 9 are visible, under the blue/black cable are 4 more holes with silver square around them.

Upper right on the schematics are the extra pins. This might be handy.

4) At 4 there is a SCL and SDA which are used for SPI I think, but these are not on the original Arduino. But the original Arduino has 6 pins at the same location and 4 holes (where 2 of them are marked as JP2).

The original has an extra ISP pins (ICSP1) for the ATmega16U2. See the schematics. The clone has the new layout I2C signals extending beyond pin 13.

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  • Thank you very much (just for my curiosity), how did you find the schematics? I don't see any clear ID. Guess it's not bad at all (and it was less than 3 euros).
    – Michel Keijzers
    Commented Mar 29, 2017 at 22:30
  • 1
    Web-search "arduino uno ch340 schematics" :) It all about the "magical" index word. In this case the USB-UART ch340 chip.
    – Mikael Patel
    Commented Mar 30, 2017 at 5:23
  • I didn't know the USB/UART chip would be that important to find the schematics
    – Michel Keijzers
    Commented Mar 30, 2017 at 7:02
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    The trick when constructing a web-search query is to consider the unique and distinguishing attribute, in this case the CH340G chip. This helps the search engine reduce the search space. Using for instance the 12 MHz crystal is not as distinguished as the Arduino itself could use that.
    – Mikael Patel
    Commented Mar 30, 2017 at 8:29
  • Thanks ... I am new to electronics so I was not aware that the CH340G was the 'unique' factor. But it will help me in future to find datasheets/schematics as well to know such information.
    – Michel Keijzers
    Commented Mar 30, 2017 at 8:56

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