3pcs Pro Mini ATmega328P 3.3V 8M Module Board with Crystal Oscillator Compatible Arduino Pro Mini Replace ATmega128

Liked - works reliably, takes a lot of abuse and still keeps on ticking Dislikes - Not an issue with this specific supplier, but across multiple suppliers the header for the serial link is not consistent. Some suppliers the ground pins are on the right and other suppliers the ground pins are on the left side.

Always get what pay for. Good products, good price, good availability.

I wish I had taking the time to read the reviews before I bought these boards. Very very poorly made, they even typos in the silk screen pin labels. Like many others have complained about I was unable to upload to them even after burning a new bootloader. After some investigation I found that they had the wrong crystal installed. The 3v3 8Mhz board had a 16Mhz crystal installed. The ATMega328p does not run reliably at 16Mhz with a 3v3 vcc. I ordered boards without USB converters because I had a limited power budget. I am running off of batteries so I really didn't need the regulator. I removed it and flashed the 5v 16Mhz bootloader and then enabled a clock divider in my project code. I can use them now, but I'll never buy form this vendor again!

Works great if you actually know what you're doing. These are rated at 3.3V so if you want magic smoke genies then just apply 5 volts.

All three Arduino Pro Minis were successfully used for Mail Alert System project. The board appeared to be resilient and no problems when I accidentally connected 8 - 9 Volt to VCC momentarily. It survived the higher voltage. But I had to learn how to upload the sketch with a trick. For a couple of days, I was not happy at all when I could not upload a sketch. As a one Youtuber said, the reset button must be pressed right after you click on upload sketch. I also did numerous restarted my computer. After I learned the trick, I have no issues with the board. Good purchase. I would give 5 stars if I did not go through the pain of learning the upload process with trick. I would buy again definitely.

Works perfectly for what I needed it for.

First, I found the quality of the modules assembly to be good. However, I was not able to use the Arduino IDE to load a program using a USB to Serial converter as one would expect. I eventually discovered that the 3 modules I received did NOT have a bootloader installed as was specified in the HiLetgo ad. I contacted the seller for support providing a screen shot of the error message I received when trying to upload a program and they responded quickly, providing a pinout diagram and suggested IDE menu selections but no help regarding the error message. I did some investigation an learned that the error was typical of a module that DID NOT have a bootloader. To prove the point I built an ICSP and uploaded a proper bootloader. The module then performed as expected, hence, the CAUTION, be prepared to build or buy an ICSP device to burn the bootloader. I now notice several other reviewers commenting on the same problem of a missing bootloader. Unfortunately, these modules will be returned for a refund and I will look elsewhere as I am preparing to publish an article that will use the Arduino Pro Mini and I cannot reference this module from HiLetgo knowing that it will most likely cause problems. Other than the missing bootloader, the one module I got working seems to be OK.

Functions as expected