The ARM Cortex-M4F processor was developed to provide a low-cost platform that meets the needs of MCU implementation, with a reduced pin count and low-power consumption, while delivering outstanding computational performance and an advanced system response to interrupts. The ARM Cortex-M4F 32-bit RISC processor features exceptional code efficiency, delivering the high performance expected from an ARM core in the memory size usually associated with 8-bit and 16-bit devices. It also features a Floating Point Unit (FPU) which supports all ARM single-precision data-processing instructions and data types.
The STM32F405 Performance Line family has an embedded ARM core and is therefore compatible with all ARM tools and software. It combines the high-performance ARM Cortex-M4F CPU with an extensive range of peripheral functions and enhanced I/O capabilities. In addition, it implements a full set of DSP instructions and a memory protection unit (MPU) which enhances application security.
STM32-P405 is a good board for experimenting with the STM32F405 processor. It has RS232, USB and CAN interfaces on board, and a prototyping area with all the MCU signals near it so you can implement your own circuit. In addition, it has a UEXT port for easy connection of add-on peripheral modules.