CT-UNO micro-B USB not working?

Nowadays, Arduino is so popular that even secondary students are using it for hobby work! Arduino UNO is the most popular and easiest to start with for beginners, so we use UNO in most examples and tutorials. Since then, Cytron has come up with our own UNO called CT-UNO. There are a lot of special features compared to Arduino UNO, for example CT-UNO uses micro-B instead of USB-B on UNO. You can see all the features in introduction to CT-UNO.

Anyhow, we noticed the micro-B socket/receptor on the CT-UNO is kind of fragile. Some users report that the receptor loosens after some usage, which may cause the USB connection and power connection to be unstable. In some cases, the entire micro-B USB receptor is peel off the PCB. We know that and since then has improved the CT-UNO design by using a better micro-B USB socket and modify the PCB layout too. Now, the CT-UNO has a very strong micro-B receptor 

You can always contact us at support@cytron.com.my and claim warranty if your USB connection is not stable or the micro-B socket peel off. 

Figure (a). Earlier version of CT-UNO

MicroB USB peeled off
Figure (b). MicroB socket was peeled off

MicroB USB socket for older version of CT-UNO
Figure (c). MicroB socket for older version of CT-UNO

MicroB USB socket of latest version of CT-UNO
Figure (d). MicroB socket of latest version of CT-UNO

Earlier when we are using MicroB socket like shown in Figure (c), the bonding between the socket and PCB is not strong enough. Don’t get me wrong, it is usable, but not for rough usage, so for some user, it may peel off, like shown in in figure (b). So, then we improved the design by using MicroB socket in figure (d) that provide more robust and rugged design than before. 

If you are urgent and need to load program without micro-B USB, follow this tutorial! Though you will need some extra devices to perform external program loading. The method is similar to loading program into PRO-Mini, but with a few more tweaks!


1) Male to male jumpers 

2) 1uF(105) Ceramic capacitor 

3) UC00A (USB to UART converter)

4) USB Mini Cable

5) Breadboard


UC00A is a USB to UART converter and we normally use with Arduino Pro Mini. For this case you can use this to help you to load the program. It has six pins which are DTR, RX, TX, Vsel, CTS, and GND. You have to connect all 6-pin to your CT-UNO using male to male jumper wire. It will be easy for you to troubleshoot later if you use different colour for each pins.

DTR of  UC00A – to Reset pin of CT-UNO through 1uF ceramic capacitor /orange

RX of UC00A – to TX (pin 1) of CT-UNO/green

TX of UC00A – to RX (pin 2) of CT-UNO/brown

Vsel of UC00A – to 5V of CT-UNO/red

CTS of UC00A – to GND of CT-UNO/blue

GND of UC00A – to GND of CT-UNO/black

The configuration of the circuit is shown in the picture below.

Configuration of the circuit

Configuration of the circuit using fritzing

DTR or data terminal ready is a control signal for serial communication, output from computer to a device to indicate that terminal is ready for communication. DTR pin must be connected to Reset pin via a capacitor. This is because DTR will be low all the time whenever the serial port is active. Hence,the capacitor turns that level into a pulse. If the DTR is connected to reset directly without capacitor, the Arduino Reset pin will always be low and this would make Arduino permanently in reset stage. You will not be able to load the program if this occurs. So, the capacitor acts like a differentiator in this case.

Note that if you don’t have ceramic capacitor you also can use Electrolyte Capacitor. But please do be careful with the polarity.

Connect your USB Mini Cable with your computer and UC00A. If this is your first time using UC00A, you might need to install the driver. Please do note that Com Port number will be different as you are now using UC00A instead of CT-UNO directly. For example when I connect the CT-UNO using micro-USB B cable, it shows COM port 172.

But now with UC00A, it shows COM port 171.


Now try load LED Blinking coding to your CT-UNO and you can see that the LED on CT-UNO is blink according to your coding or program. 

There is also another method of loading your program – loading through ISP. Here is link of tutorial to load the program using USBasp.

If you have any technical inquiries, please post in our technical forum as we seldom check the comments section in tutorial site.

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