原标题：ST STM32L475Discovery物联网(IOT)开发方案

　　ST公司的STM32L475是超低功耗高性能MCU,采用32位带DSP和浮点单元(FPU)的ARM® Cortex®-M4内核,工作频率80MHz,系列产品提供256KB到1MB闪存,存储器可采用SDIO,Quad-SPI 和FSMC接口扩展,并集成了USB OTG,DFSDM,提供多达3个快速12位ADC,两个比较器,两个运放,两个DAC通路,内部基准电压缓冲器,低功率RTC,两个通用32位计时器,两个用于马达控制的16位PWM计时器,七个通用16位计时器和两个16位低功耗计时器.主要用在各种低功耗应用如物联网(IoT)等.本文介绍了STM32L475xx系列主要特性,框图,以及时钟树框图,Discovery开发板B-L475E IOT01A主要特性,框图,电路图和材料清单.

　　The STM32L475xx devices are the ultra-low-power microcontrollers based on the high-performance ARM® Cortex®-M4 32-bit RISC core operating at a frequency of up to 80 MHz. The Cortex-M4 core features a Floating point unit (FPU) single precision which supports all ARM single-precision data-processing instructions and data types. It also implements a full set of DSP instructions and a memory protection unit (MPU) which enhances application security. The STM32L475xx devices embed high-speed memories (Flash memory up to 1 Mbyte, up to 128 Kbyte of SRAM), a flexible external memory controller (FSMC) for static memories (for devices with 100 pins package), a Quad SPI flash memories interface (available on all packages) and an extensive range of enhanced I/Os and peripherals connected to two APB buses, two AHB buses and a 32-bit multi-AHB bus matrix.

　　The STM32L475xx devices embed several protection mechanisms for embedded Flash memory and SRAM: readout protection, write protection, proprietary code readout protection and Firewall. The devices offer up to three fast 12-bit ADCs (5 Msps), two comparators, two operational amplifiers, two DAC channels, an internal voltage reference buffer, a low-power RTC, two general-purpose 32-bit timer, two 16-bit PWM timers dedicated to motor control, seven general-purpose 16-bit timers, and two 16-bit low-power timers. The devices support four digital filters for external sigma delta modulators (DFSDM). In addition, up to 21 capacitive sensing channels are available. They also feature standard and advanced communication interfaces.

　　• Three I2Cs • Three SPIs

　　• Three USARTs, two UARTs and one Low-Power UART.

　　• Two SAIs (Serial Audio Interfaces)

　　• One SDMMC

　　• One CAN

　　• One USB OTG full-speed

　　• One SWPMI (Single Wire protocol Master Interface)

　　The STM32L475xx operates in the -40 to +85 °C (+105 °C junction), -40 to +105 °C (+125 °C junction) and -40 to +125 °C (+130 °C junction) temperature ranges from a 1.71 to 3.6 V power supply. A comprehensive set of power-saving modes allows the design of low-power applications. Some independent power supplies are supported: analog independent supply input for ADC, DAC, OPAMPs and comparators, 3.3 V dedicated supply input for USB and up to 14 I/Os can be supplied independently down to 1.08V. A VBAT input allows to backup the RTC and backup registers. The STM32L475xx family offers two packages from 64-pin to 100-pin packages.

　　STM32L475xx系列主要特性:

　　• Ultra-low-power with FlexPowerControl

　　– 1.71 V to 3.6 V power supply

　　– -40 °C to 85/105/125 °C temperature range

　　– 300 nA in VBAT mode: supply for RTC and 32x32-bit backup registers

　　– 30 nA Shutdown mode (5 wakeup pins)

　　– 120 nA Standby mode (5 wakeup pins)

　　– 420 nA Standby mode with RTC

　　– 1.1 μA Stop 2 mode, 1.4 μA Stop 2 with RTC

　　– 100 μA/MHz run mode

　　– Batch acquisition mode (BAM)

　　– 4 μs wakeup from Stop mode

　　– Brown out reset (BOR) in all modes except shutdown

　　– Interconnect matrix

　　• Core: ARM® 32-bit Cortex®-M4 CPU with FPU, Adaptive real-time accelerator (ART Accelerator™) allowing 0-wait-state execution from Flash memory, frequency up to 80 MHz, MPU, 100DMIPS/1.25DMIPS/MHz (Dhrystone 2.1), and DSP instructions

　　• Clock Sources

　　– 4 to 48 MHz crystal oscillator

　　– 32 kHz crystal oscillator for RTC (LSE)

　　– Internal 16 MHz factory-trimmed RC (±1%)

　　– Internal low-power 32 kHz RC (±5%)

　　– Internal multispeed 100 kHz to 48 MHz oscillator, auto-trimmed by LSE (better than ±0.25 % accuracy)

　　– 3 PLLs for system clock, USB, audio, ADC

　　• RTC with HW calendar, alarms and calibration

　　• Up to 21 capacitive sensing channels: support touchkey, linear and rotary touch sensors

　　• 16x timers: 2 x 16-bit advanced motor-control, 2 x 32-bit and 5 x 16-bit general purpose, 2x 16-bit basic, 2x low-power 16-bit timers (available in Stop mode), 2x watchdogs, SysTick timer

　　• Up to 114 fast I/Os, most 5 V-tolerant, up to 14 I/Os with independent supply down to 1.08 V

　　• Memories

　　– Up to 1 MB Flash, 2 banks read-while-write, proprietary code readout protection

　　– Up to 128 KB of SRAM including 32 KB with hardware parity check

　　– External memory interface for static memories supporting SRAM, PSRAM and NOR memories

　　– Quad SPI memory interface

　　• 4x digital filters for sigma delta modulator

　　• Rich analog peripherals (independent supply)

　　– 3× 12-bit ADC 5 Msps, up to 16-bit with hardware oversampling, 200 μA/Msps

　　– 2x 12-bit DAC, low-power sample and hold

　　– 2x operational amplifiers with built-in PGA

　　– 2x ultra-low-power comparators

　　• 18x communication interfaces

　　– USB OTG 2.0 full-speed, LPM and BCD

　　– 2x SAIs (serial audio interface)

　　– 3x I2C FM+(1 Mbit/s), SMBus/PMBus

　　– 6x USARTs (ISO 7816, LIN, IrDA, modem)

　　– 3x SPIs (4x SPIs with the Quad SPI)

　　– CAN (2.0B Active) and SDMMC interface

　　– SWPMI single wire protocol master I/F

　　• 14-channel DMA controller

　　• True random number generator

　　• CRC calculation unit, 96-bit unique ID

　　• Development support: serial wire debug (SWD), JTAG, Embedded Trace Macrocell™

　　图1.STM32L475xx系列框图

　　图2.STM32L475xx系列时钟树框图

　　STM32L4Discovery开发板B-L475E IOT01A

　　The STM32L4 Discovery kit for IoT node (B-L475E-IOT01A) allows users to develop applications with direct connection to cloud servers. The STM32L4 Discovery kit enables a wide diversity of applications by exploiting low-power multilink communication (BLE, Sub-GHz), multiway sensing (detection, environmental awareness) and ARM® Cortex®-M4 core-based STM32L4 Series features. Arduino™ Uno V3 and PMOD connectivity provide unlimited expansion capabilities with a large choice of specialized add-on boards. The STM32L4 Discovery kit includes an ST-LINK debugger/programmer, and comes with the comprehensive STM32Cube software libraries together with packaged software examples to seamlessly connect to cloud servers.

　　图3.Discovery开发板B-L475E IOT01A外形图

　　图4.Discovery开发板B-L475E IOT01A主要元件分布图(顶层)

　　图5.Discovery开发板B-L475E IOT01A主要元件分布图(底层)

　　Discovery开发板B-L475E IOT01A主要特性:

　　• Ultra-low-power STM32L4 Series MCUs based on ARM® Cortex®-M4 core with 1 Mbyte of Flash memory and 128 Kbytes of SRAM, in LQFP100 package.

　　• 64-Mbit Quad-SPI (Macronix) Flash memory

　　• Bluetooth® V4.1 module (SPBTLE-RF)

　　• Sub-GHz (868 or 915 MHz) low-power-programmable RF module (SPSGRF-868 or SPSGRF-915)

　　• Wi-Fi® module Inventek ISM43362-M3G-L44 (802.11 b/g/n compliant)

　　• Dynamic NFC tag based on M24SR with its printed NFC antenna

　　• 2 digital omnidirectional microphones (MP34DT01)

　　• Capacitive digital sensor for relative humidity and temperature (HTS221)

　　• High-performance 3-axis magnetometer (LIS3MDL)

　　• 3D accelerometer and 3D gyroscope (LSM6DSL)

　　• 260-1260 hPa absolute digital output barometer (LPS22HB)

　　• Time-of-Flight and gesture-detection sensor (VL53L0X)

　　• 2 push-buttons (user and reset)

　　• USB OTG FS with Micro-AB connector

　　• Expansion connectors:

　　– Arduino™ Uno V3

　　– PMOD

　　• Flexible power-supply options:

　　– ST-LINK USB VBUS or external sources

　　• On-board ST-LINK/V2-1 debugger/programmer with USB re-enumeration capability: mass storage, virtual COM port and debug port

　　• Comprehensive free software including a variety of examples, as part of the STM32Cube package, as well as a cloud connector software expansion, enabling direct access to cloud servers

　　• Support of wide choice of Integrated Development Environments (IDEs) including IAR™, Keil®, GCC-based IDEs

　　• ARM® mbed-Enabled™ (see http://mbed.org)

　　详情请见:

en.DM00347848.pdf

en.DM00347837.pdf

en.DM00172872.pdf