64 KB Flash / 20 KB SRAM — sizing the firmware and data buffers
The 64 KB Flash (64K x 8) is the mid-density option in the STM32F103 line, suitable for control firmware with a modest application layer — think CANopen stacks, USB HID or CDC class drivers, or sensor-fusion algorithms. The 20 KB SRAM (20K x 8) provides enough working memory for two or three moderate-sized data buffers alongside the stack and heap. If your application needs more than 64 KB of code space, the STM32F103x8/xB variants (128 KB Flash) are the next step up, though they come in larger packages.
Peripheral integration: CAN, USB, and motor-control PWM on one die
This MCU integrates a CANbus controller (2.0B active) and a USB 2.0 full-speed device interface, both of which are often separate external chips in older designs. The motor-control PWM timer with complementary outputs and dead-time insertion is wired for driving 3-phase inverter stages — a common requirement in brushless DC motor drives. The 10-channel 12-bit ADC samples at up to 1 µs per channel, enough for current-sense feedback loops running at typical PWM switching frequencies. DMA is available to move ADC results to SRAM without CPU intervention, freeing the core for control math.
The STM32F1 series remains a mainstream offering from ST, widely second-sourced through the independent distribution channel.