72 MHz Cortex-M3 with 128 KB Flash – the mid-density workhorse
The STM32F103VBT6TR: This MCU is part of the STM32F1 series, an ARM Cortex-M3 family. The 128 KB Flash is the mid-density option in the STM32F103 line — enough for a FreeRTOS image with a modest application layer, but not the multi-megabyte tier needed for GUI frame buffers or over-the-air staging on a full filesystem. The 20 KB SRAM supports a few moderate-sized buffers; designs that queue large CAN or USB payloads should budget the RAM allocation early.
Peripherals and connectivity set
On the peripheral side, this MCU includes DMA, a motor-control PWM timer, a temperature sensor, and a watchdog — the usual complement for a motor-drive or power-conversion controller. The 80 available I/O in the 100-LQFP package leave plenty of pins for parallel sensor arrays or a parallel LCD interface. The internal oscillator means a basic blink-and-ADC application can run without an external crystal, saving two pins and a few cents on the BOM. For USB or CAN operation, an external resonator or crystal is still recommended for clock accuracy.
The ROHS3 compliance is confirmed, which keeps it clear of the RoHS exemption phase-outs that affect some older STM32F1 date codes.
TR suffix – tape-and-reel vs tray
The silicon, firmware, and pinout are identical — the only difference is the shipping medium. If your pick-and-place line is set up for reel-fed 100-LQFP, the TR variant saves a manual tray-handling step. For prototyping or low-volume builds, the tray version may be more convenient, but both are electrically interchangeable.