Historically, the Arduino Mini Pro has been one of the favorite models for expert users of Arduino. Its low cost and small size made it the perfect model for projects where Arduino became part of the assembly permanently.
However, its small cost and size had a negative side, and that is the Arduino Mini Pro lacks a USB circuit. As a result, the Arduino Mini Pro has to be programmed using an external USB-TTL converter.
Currently, due to the decrease in price of the Arduino Nano, interest in the Arduino Mini Pro has decreased significantly. The Arduino Nano does incorporate a Micro USB port and is much easier and faster to use (seriously, buy Arduino Nano, you will gain mental health).
But just in case you still have to deal with an Arduino Mini, or if you have one stored in a drawer, or, especially, because it is interesting to delve into the internal functioning of Arduino, let’s see how to program an Arduino Mini Pro.
What is the FTDI FT232R?
To be able to program an Arduino Mini Pro, we need a device that replaces the USB circuit that most Arduino models have.
The most common programmer is the FT232R model from FTDI (Future Technology Devices International) with a cost of around 1.5€.
The FTDI FT232R is a device that serves for more than just programming Arduino Mini Pro. It is interesting to have one in our Geek toolbox.
Install the Driver
Most Linux distributions include drivers for the FTDI FT232R. However, this is not the case in any of the Windows versions.
Fortunately, if you are using a Windows operating system (or a Linux distribution that does not include the drivers), the solution is as simple as downloading and installing the drivers from the manufacturer’s website.
Here we select VPC Drivers (Virtual COM Ports) and choose the most current driver available. In the case of Windows, make sure to download the executable installer, instead of the compressed file, as the installation is simpler.
After installing the driver, we connect the FTDI FT232R. We go to devices, and in COM ports we locate the one corresponding to the FTDI FT232R. We right-click and choose “Properties”.
Here, in advanced options, we activate the “High RST on close” option. This will restart Arduino when loading the program, something necessary for the Arduino programming process.
Connect Arduino Mini Pro and FTDI FT232R
Connecting the Arduino Mini Pro to the FTDI Pro is simple. We just have to connect the 6 FTDI FT232R connectors to the 6 front pins of the Arduino Mini Pro FTDI interface.
The connection can be made using normal conductors with female dupont terminals or, for quick tests, we can connect both frontals directly on a protoboard, putting them facing each other.
Next, we connect the FTDI FT232R to the computer via USB. In the Arduino environment, we select the corresponding COM port, the Mini Pro board model, and as a programmer, we leave the one we usually use “AVRISP mkII”.
Ready, we can load programs normally and use the serial port as in any other Arduino model.