thats right, more memory, features, and performance than similar “avr-duinos” all for less than 2 dollars free shipping. so maybe if microchip phases out or bumps atmel prices too far then all might not be lost:
STM32F103C8T6. ARM 32 bit Cortex-M3 CPU.
Debug mode: SWD.
64K flash memory, 20K SRAM.
2.0-3.6V power, I/O.
72MHz work frequency.
RTC with 32khz crystal and battery auto-backup circuit
On-board Mini USB interface, you can give the board power supply and USB communication.
even cheaper on aliexpress but i dont mind paying a few cents more for ebay protection. i already had a couple dozen from when they were 3 bucks, but what the heck, couple dozen more wont hurt.
thanks to roger clark and the people whos work he built upon it is programmable from arduino ide. although i do prefer the manufacturers built-in serial bootloader to the oddball usb kluge popular on that web site.