Hi !
The STM32 Nucleo plaftorm rocks, it is way better bang for the bucks than Arduino for DIY, especially if you need a lot of IOs.
The offer is very complete and it offers interesting key features:
- Wide range of 32 bit ARM Cores: ARM M0, M3, M4 and M7 !
- High speed DMA controlled 12bits ADC (up to 2 Million Samples per second).
- Correct DAC on 12bits for some of them with I2S
- Integrated Debugger/JTAG/Programmer: for debugging it is really important, Arduino are lacking this.
- 5V tolerant IOs: robustness, less easy to fry board.
- Different number of IOs: 25, 50 to 144 !
- ARM MBED Libraries and various supports in RealTime OSs. It exists an Arduino IDE port with libraries, but I do not use it.
- Very competitive pricing especially on the 50 and 144 boards: 10, 15 to 24 USD
- Ethernet port on the 144 boards
- Widely available through high reputation vendors: Mouser, Farnell ...
Follows a few links to give you an idea of the platform:
- 25 IOs : https://os.mbed.com/platforms/ST-Nucleo-F031K6/
- 50 IOs: https://os.mbed.com/platforms/ST-Nucleo-F411RE/, https://os.mbed.com/platforms/ST-Nucleo-F446RE/
- 144 IOs: https://os.mbed.com/platforms/ST-Nucleo-F767ZI/, there is a new board that goes up to 400 Mhz it allows to do very interesting things for a 24 USD board: NUCLEO-H743ZI
Personally I own a few NUCLEO-F411RE, NUCLEO-F446RE used for hobby and prototyping. I converted also a friend who is an Arduino addict to this platform.
I use a Cross GCC, ARM MBED, OpenOCD and StLink.