Item specifics
Description
STM32L071RBT6 Product Overview
STM32L071RBT6 is a Cortex-M0+ MCU at 32 MHz, LQFP-64. 128 KB Flash, 20 KB SRAM, 6 KB EEPROM, USB 2.0 FS device (crystal-less), 12-bit ADC (16 ch), 12-bit DAC, two comparators, capacitive touch channels, LP timers, RTC, 2×USART, 1×UART, 2×SPI, 2×I2C. Up to 51 x 5 V-tolerant I/Os. 1.65–3.6 V, -40–85 °C. Compared to the 48-pin L071CBT6, it offers more I/Os, providing a cost-effective ultra-low-power solution for battery-powered IoT nodes and portable devices needing richer connectivity, large storage, and USB communication.
STM32L071RBT6 Core Features
Core: Cortex-M0+ 32 MHz, low-power design
Memory: 128 KB Flash, 20 KB SRAM, 6 KB EEPROM
USB: USB 2.0 FS device (crystal-less)
Analog: 12-bit ADC (16 ch), 12-bit DAC, 2×Comparators, capacitive touch
Connectivity: 2×USART, 1×UART, 2×SPI, 2×I2C
Timers: LP Timer, GP Timers, RTC
I/Os: 51 (5 V-tolerant)
Package: LQFP-64
Temperature Range: -40°C to 85°C
STM32L071RBT6 Applications
IoT Sensor Nodes: Battery-powered wireless sensors, USB data acquisition modules
Portable Devices: Wearables, portable medical devices, USB peripherals
Industrial Metering: Water, gas, and electricity meters
Consumer Electronics: Remote controls, e-labels, smart cards
Energy Harvesting Applications: Self-powered sensor nodes
STM32L071RBT6 Key Advantages
128 KB Flash + 20 KB SRAM + 6 KB EEPROM: Massive memory for complex programs and data logging
USB + DAC + Comparators: Crystal-less USB, analog output, and comparators — comprehensive feature set
Capacitive Touch Sensing: Built-in touch channels for easy button and slider implementation
51 I/Os in LQFP-64 Package: Rich pins for multi-peripheral connectivity
Ultra-Low Power: Multiple low-power modes extend battery life
5 V-tolerant I/Os: Enhanced robustness, simplified level shifting
Full Ecosystem Compatibility: Easy development with STM32CubeIDE/HAL/LL libraries
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FAQ
1. What is STM32L071RBT6 and where does it fit in the STM32L0 series?
STM32L071RBT6 is an ultra-low-power 32-bit MCU from STMicroelectronics' STM32L0 series, built around an Arm® Cortex®‑M0+ core in an LQFP‑64 package. Running at 32 MHz, it provides 128 KB Flash and 20 KB SRAM, and integrates a USB 2.0 full‑speed device controller and a 12‑bit ADC. As the mid‑range Flash variant in the L071 family, it omits the segment LCD driver, DAC, and capacitive touch sensing (TSC) to deliver powerful ultra‑low‑power processing, USB connectivity, and essential analog acquisition at an optimal balance of cost and performance for battery‑powered devices.
2. What are the key specifications of STM32L071RBT6?
Core: Arm® Cortex®‑M0+, up to 32 MHz
Memory: 128 KB Flash, 20 KB SRAM
Operating Voltage: 1.65 V to 3.6 V
Temperature Range: -40 °C to +85 °C (industrial grade)
I/O Count: up to 51
Package: LQFP‑64 (10 mm × 10 mm)
3. How does STM32L071RBT6 differ from STM32L071RZT6? How do I choose based on Flash size?
Both share identical packages, pinouts, and peripherals—including USB, ADC, and all ultra‑low‑power modes. The sole difference is Flash capacity: RBT6 has 128 KB, while RZT6 has 192 KB. If your firmware fits within 128 KB, the RBT6 delivers the same functionality and performance at a lower cost. For extra space to accommodate more complex protocol stacks, data logging, or OTA upgrade code, the RZT6 provides additional headroom.
4. Compared to the L072 and L073 series, what peripherals does the L071 lack? How should I choose for my project?
The L071 series is positioned as the value‑line entry in the L0 family. It removes the segment LCD driver (found on L072/L073), the 12‑bit DAC, and the capacitive touch sensing TSC (found only on L073), while retaining the core USB and ADC. If your application does not require a segment display, analog voltage output, or touch keys, the L071 delivers identical processing performance and ultra‑low‑power characteristics at a more competitive cost. Upgrade to the L072 or L073 if those features are needed.
5. What real‑world applications can the 128 KB Flash and 20 KB SRAM combination support? Is it sufficient?
The 128 KB Flash comfortably accommodates a lightweight RTOS (such as FreeRTOS), USB device stacks (CDC virtual COM port or HID), common sensor drivers, and communication middleware. The 20 KB SRAM is suitable for relatively fixed‑function applications like data acquisition, protocol conversion, and wireless sensor nodes that do not need large display buffers. If additional RAM is later required, external PSRAM can be added via SPI, or you can migrate to the STM32L1 series with larger SRAM.
6. How does it perform in terms of ultra‑low power consumption? What are the typical currents across its modes?
Temperature Range: -40 °C to +85 °C
Ultra‑low‑power modes:
Standby mode: ~0.27 µA (no RTC)
Stop mode: ~0.4 µA (no RTC), ~0.8 µA with RTC
Run mode: ~88 µA/MHz
7. What can the USB 2.0 full‑speed device interface do, and why must an external crystal be used?
The USB controller can be configured as a CDC virtual COM port (for serial communication with a PC or smartphone), an HID keyboard/mouse, or an MSC mass storage device for data exchange, parameter configuration, and firmware updates. USB protocol demands extremely tight clock accuracy (≤0.25% tolerance), which the internal RC oscillator cannot meet. An external high‑precision 8 MHz or 16 MHz crystal is therefore mandatory; otherwise, the device will fail to enumerate or communicate reliably.
8. If my project needs a segment display or analog output, can the L071 be expanded externally?
Yes. For segment displays, you can connect an external segment LCD driver chip (e.g., HT1621) via I²C or SPI. For analog output, you can use a PWM channel with an external RC low‑pass filter to generate low‑frequency analog voltages, or connect a low‑cost DAC chip (e.g., MCP4725) via SPI/I²C. If these features are core requirements, upgrading directly to the L073 series, which integrates a segment LCD and DAC on‑chip, is a more efficient solution.
9. What development tools are needed for the STM32L071RBT6? Is there a compatible evaluation board?
ST provides free STM32CubeMX for graphical configuration and STM32CubeIDE as an integrated development environment, along with the STM32CubeL0 firmware library. Debugging and programming are handled by ST‑Link debuggers. For rapid prototyping, the NUCLEO‑L073RZ board is highly compatible—though it carries an L073 chip, the L071 shares the same core architecture and USB/ADC peripherals, so code can be ported with minimal adjustments.
10. What upgrade options are available if I need more Flash or richer peripherals in the future?
If you simply need more Flash, you can drop‑in upgrade to the fully pin‑compatible STM32L071RZT6 (192 KB Flash) with zero hardware changes. If you need to add a segment display, DAC, or touch sensing, choose the same‑package, pin‑compatible STM32L073RBT6 or RZT6. If significantly higher computing power or a color TFT display is desired, consider the STM32L4 series, but note that most L4 devices lack a segment LCD driver and DAC, so the display and analog output strategies may need to be redesigned.