Item specifics
Description
The STM32F105R8T6 is a Connectivity Line Cortex-M3 MCU from STMicroelectronics in an LQFP-64 package (10×10×1.4 mm). It features a 72 MHz Cortex-M3 core at 1.25 DMIPS/MHz with 64 KB Flash and 20 KB SRAM. This model belongs to the STM32F105xx family, designed for embedded systems requiring USB OTG, CAN, and Ethernet communication. The MCU integrates USB 2.0 OTG full-speed device/host/OTG (with on-chip PHY), Ethernet 10/100 MAC (with dedicated DMA and SRAM), dual CAN 2.0B (512 bytes dedicated SRAM), dual 12-bit ADCs (16 channels, 1 µs), dual 12-bit DACs, 12-channel DMA, up to 10 timers (including 1 motor control PWM with deadtime/emergency stop), and up to 14 communication interfaces (5×USART/3×SPI/2×I2C/2×I2S/USB OTG/CAN/Ethernet). 51 I/Os (LQFP-64 package), all 5 V-tolerant. Supply 2.0–3.6 V, -40–85 °C, ECOPACK®2. Comparison with similar models: This model belongs to the STM32F105xx Connectivity Line, positioned between the STM32F103 performance line and the STM32F107 full Ethernet line. Compared to the STM32F103R8T6 (64 KB Flash/20 KB SRAM), it adds USB OTG, dual CAN, Ethernet MAC, and richer communication interfaces. Compared to the STM32F105RCT6 (256 KB Flash/64 KB SRAM), it has 64 KB Flash and 20 KB SRAM (vs. 256 KB/64 KB), while all other peripherals remain identical.
Core: Arm Cortex-M3 72 MHz, 1.25 DMIPS/MHz, single-cycle multiplication/hardware division, SWD & JTAG debug Memory: 64 KB Flash, 20 KB SRAM, CRC, 96-bit unique ID USB 2.0 OTG FS: Device/host/OTG, on-chip PHY, HNP/SRP/ID support Ethernet MAC: 10/100 Mbit/s, dedicated DMA and SRAM, MII/RMII support Dual CAN 2.0B: 512 bytes dedicated SRAM, 11 filters per CAN Dual 12-bit ADCs: 16 channels, 1 µs, 0–3.6 V, sample and hold, temperature sensor, up to 2 MSPS in interleaved mode Dual 12-bit DACs: Buffered output DMA: 12 channels, supporting timers, ADCs, DAC, I2Ss, SPIs, I2Cs, USARTs Up to 10 Timers: 1× motor control PWM (deadtime/emergency stop), up to 4× 16-bit GP (quadrature encoder), 2× basic (DAC drive), 2× watchdogs, SysTick Up to 14 Communication Interfaces: 2×I2C (SMBus/PMBus), 5×USART (ISO7816/LIN/IrDA), 3×SPI (18 Mbit/s), 2×I2S, USB OTG FS, 2×CAN 2.0B, Ethernet MAC Low Power: Sleep/Stop/Standby, VBAT backup RTC and backup registers Clock: 3–25 MHz XTAL, 32 kHz RTC XTAL, 8 MHz RC, 40 kHz RC, PLL I/Os: 51, all 5 V-tolerant Package: LQFP-64 (10×10×1.4 mm), Tray
Industrial Automation: PLCs, inverters, industrial Ethernet gateways, dual CAN communication nodes Motor Control: Fans, pumps, small motors (motor control PWM/deadtime/emergency stop) Medical: Handheld medical terminals, health monitoring devices Consumer: Remote controls, handhelds, PC peripherals, GPS platforms Home Appliances: Panels, HVAC, alarms, video intercoms Security: Access control, alarms, smoke detectors IoT: Wireless sensors, environmental monitoring, smart home Automotive: Light control, window anti-pinch, sensor nodes (non-safety-critical) Printers & Scanners, Home Audio
Connectivity Line: USB OTG + dual CAN + Ethernet MAC triple interface — rare in this class USB OTG FS: On-chip PHY, device/host/OTG support without external PHY Ethernet MAC: 10/100 Mbit/s with dedicated DMA and SRAM, MII/RMII support Dual CAN 2.0B: 512 bytes dedicated SRAM for dual industrial bus communication 72 MHz Cortex-M3: 1.25 DMIPS/MHz, single-cycle multiplication/hardware division 64 KB Flash + 20 KB SRAM: For low-to-medium complexity communication stacks and algorithms 12-ch DMA: Direct peripheral-to-memory transfers, offloads CPU 14 Communication Interfaces: 5×USART + 3×SPI + 2×I2C + 2×I2S + USB OTG + 2×CAN + Ethernet 51 I/Os: LQFP-64 package, all 5 V-tolerant Mature STM32 Ecosystem: CubeIDE/CubeMX/HAL/LL
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FAQ:
What is the STM32F105R8T6 and how does it differ from the STM32F107R8T6?
The STM32F105R8T6 is a 72 MHz Arm Cortex‑M3 microcontroller with 64 KB Flash and 64 KB SRAM, housed in an LQFP‑64 package. It is the USB‑centric member of the STM32 "connectivity line," featuring a USB OTG controller with integrated PHY and two CAN 2.0B interfaces. The key difference from the STM32F107R8T6 is that the F105 omits the Ethernet MAC. This makes the F105 the more cost‑focused choice for applications that need high‑speed USB and dual CAN connectivity in a compact 64‑pin footprint, but do not require wired networking.
How does the STM32F105R8T6 compare to the STM32F105RCT6? When should I choose the R8T6?
Both share the same core, 64 KB SRAM, USB OTG, dual CAN, and LQFP‑64 package. The only difference is Flash size: the R8T6 provides 64 KB, while the RCT6 offers 256 KB. Choose the R8T6 when your firmware fits within 64 KB and you want the most cost‑effective entry into the F105 family. The pin‑compatible RCT6 gives a direct upgrade path if more code space is needed later.
Is 64 KB Flash and 64 KB SRAM enough for a USB OTG stack, dual CAN, and an RTOS?
Yes, for dedicated, well‑optimized applications. A lightweight RTOS, a USB host stack (e.g., for a flash drive or HID), a CANopen protocol, and application logic can be tightly packed into 64 KB of Flash. The 64 KB SRAM is generous for communication buffers and real‑time data, which is unusual for this Flash size. Many proven industrial designs use this configuration. If your firmware grows later, the pin‑compatible STM32F105RCT6 (256 KB Flash) provides a direct drop‑in upgrade.
Can the STM32F105R8T6 run USB OTG and dual CAN simultaneously on the 64‑pin package?
Yes, with careful pin planning. The USB OTG FS controller uses dedicated pins, and the two CAN 2.0B ports can be assigned to separate I/O locations. You can allocate USB OTG, dual CAN, and several UART/SPI/I2C interfaces without conflicts. STM32CubeMX helps you verify the exact pin‑multiplexing. This makes the R8T6 a powerful, ultra‑compact communication hub even in its space‑saving LQFP‑64 body.
Does the STM32F105R8T6 have an external memory controller? Can I add external SRAM?
No, the STM32F105 does not include an FSMC (Flexible Static Memory Controller). External parallel memory cannot be added. For applications that need additional data buffering, you can use the SPI ports to connect serial SRAM or PSRAM. If your design absolutely requires external parallel memory, the STM32F205 or F207 series (which include an FSMC) is a more suitable choice.
Can the STM32F105R8T6 be used for USB high‑speed, or is it limited to full‑speed?
The STM32F105 provides a full‑speed USB OTG controller with an integrated PHY (12 Mbps). It does not include a high‑speed ULPI interface. For virtual COM ports, HID devices, mass‑storage hosts, or moderate‑speed data loggers, full‑speed is usually sufficient. If you need 480 Mbps USB, the STM32F205 or F405 series with a ULPI PHY is required.
How does the STM32F105R8T6 compare to the classic STM32F103R8T6? What are the key upgrades?
Both share the same 72 MHz Cortex‑M3 core, 64 KB Flash, and LQFP‑64 package, but the F105R8T6 provides significant connectivity enhancements. It adds a USB OTG controller (host/device) with integrated PHY and a second CAN 2.0B interface. The SRAM also expands from 20 KB to 64 KB. If your design needs dual CAN or USB host capability, the F105R8T6 is the direct upgrade without changing the core or Flash size.
What low‑power modes does the STM32F105R8T6 support, and is it suitable for battery‑powered devices?
It supports Sleep, Stop, and Standby modes. In Stop mode with all 64 KB SRAM retained, the typical current is around 110 µA. The chip can wake up on USB or CAN activity. While not as power‑efficient as newer STM32L series, it is suitable for battery‑powered industrial sensors and portable instruments that need periodic CAN or USB communication and spend most of their time in low‑power sleep.
How can I perform over‑the‑air (OTA) firmware updates with the 64 KB single‑bank Flash?
The 64 KB Flash can be logically partitioned into a small bootloader (e.g., 8 KB) and a compact application (≈56 KB). The 64 KB SRAM can temporarily buffer the new firmware image received via USB, CAN, or an external wireless module. A CRC or signature check ensures a safe update even without hardware dual‑bank Flash. An A/B update scheme is not practical with this Flash size; a download‑and‑overwrite approach is recommended.
What are the most typical applications for the STM32F105R8T6?
It is widely used in USB‑host data loggers, dual‑CAN motor controllers, USB‑to‑CAN bridges, industrial sensor hubs with USB connectivity, and any space‑constrained embedded system that needs a reliable Cortex‑M3 core with built‑in USB OTG and dual CAN, but does not require Ethernet. Its tiny LQFP‑64 package, generous 64 KB SRAM, and mature F1 ecosystem make it a popular choice for cost‑sensitive industrial and consumer devices where the firmware is compact and well‑optimized.