Serial.print not working or serial monitor not working

I cannot get my serial monitor to work when using my mini pro and ftdi board. Does the ftdi board not support this kind of communication? I have the following boards. I know the program is running because the led is blinking correctly. Yesterday I found out the pro mini board might be a counterfeit. I don't know if this has anything to do with it.

I am running windows 10, the arduino software I have is 1.8.9

I am running the following simple code a contributor here posted in this forum some years ago:

static const int heartbeat = 13;

void setup() {
  pinMode( heartbeat, OUTPUT );

void loop() {
  digitalWrite( heartbeat, HIGH);
  digitalWrite( heartbeat, LOW);

Thank you,


Which pins on the Pro Mini do you have the adaptor connected to ?

I am using 6 pins

I have

DTR on mini connected to DTR of FTDI
TXO mini to RX FTDI
RX mini to TX FTDI
VCC mini to VCC FTDI
GNN mini to GND FTDI (I think - tough to read)
GND mini to GND FTDI

Basically with the populated side or both boards facing up and the pins facing each other they are connected from top to bottom in order.

BTW - I tried different baud rates on the monitor and still got no printout.

Which board do you have selected from the Tools > Board menu?

WAVGAT Pro Mini - I had to download some files from their website to get this option. I didn't know what I bought and could not even load a program yesterday and received some great advice from this site to make it possible to upload and run a sketch.


There have been some reports that you need to set your Serial monitor to 1/4 of the normal baud rate when you are using the WAVGAT boards. Does it start working if you set Serial monitor to 2400?

I just tried 2400 and other rates from 300 to 19200 and none worked.


you cannot see your led blinking with above sketch. LOW time is 1000ms but HIGH is just some clock ticks.
Your board is not running above sketch.

Are you sure you selected the correct board?
See sketch under : files/examples/basic/blink

Actually you can see a small flicker. I have also changed the times to make sure I was controlling the mini pro. I also loaded the blink example in the database and it worked fine.


Thank you everyone for you help. I just received some more boards that are not WAVGAT. They work perfectly. That is the second problem with the WAVGAT boards. They are not worth the hassle.

I'm glad to hear you are able to proceed now, even though the WAVGAT boards ended being a dead end. I'm seeing reports here from quite a few beginners who bought the WAVGAT boards without realizing they use a non-standard, poorly supported microcontroller, rather than the standard ATmega328P microcontroller WAVGAT claims their boards have in their product listings, then ended up with a frustrating experience trying to get them to work. It's sad because the microcontroller WAVGAT uses is actually quite interesting, and advanced users might welcome the chance to get boards with this part on it to experiment with. However, WAVGAT decided to try to pull a scam instead of being honest about what they're selling. I recommend that you leave negative feedback for them on Aliexpress. We should not support companies who prey on the members of this community.

For anyone still trying to make it work, it turns out you have to select WAVGAT UNO R3 board when using Wavgat pro mini. For me this fixed serial print not working correctly.