基于STM32L053R8超低功耗的32位MCU氣體和液體傳感器解決方案

ST公司的stm32L053x6/8是基于Arm? Cortex?-M0+核超低功耗的32位MCU，具有高達64KB閃存，8KB SRAM，2KB EEPROM和存儲器保護單元（MPU），工作頻率從32kHz到32MHz，0.95 DMIPS/MHz，工作電壓1.65V-3.6V，工作溫度-40到125℃ ，待機模式功耗0.27 μA，主要用在氣體/水表和工業(yè)傳感器，健康和健身設備，遙控和用戶接口，PC外設，游戲和GPS設備，告警系統(tǒng)，有線和無線傳感器與視頻互連。本文介紹了STM32L053x6/8主要特性，功能框圖和時鐘樹，評估板P-NUCLEO-IKA02A1主要特性，電路圖和材料清單。

The ultra-low-power STM32L053x6/8 are offered in 3 different package types： from 48 pins to 64 pins. Depending on the device chosen， different sets of peripherals are included， the description below gives an overview of the complete range of peripherals proposed in this family. These features make the ultra-low-power STM32L053x6/8 microcontrollers suitable for a wide range of applications：

? Gas/water meters and industrial sensors

? Healthcare and fitness equipment

? Remote control and user interface

? PC peripherals， gaming， GPS equipment

? Alarm system， wired and wireless sensors， video intercom

The ultra-low-power STM32L053x6/8 microcontrollers incorporate the connectivity power of the universal serial bus （USB 2.0 crystal-less） with the high-performance Arm? Cortex?-M0+ 32-bit RISC core operating at a 32 MHz frequency， a memory protection unit （MPU）， high-speed embedded memories （up to 64 Kbytes of Flash program memory， 2 Kbytes of data EEPROM and 8 Kbytes of RAM） plus an extensive range of enhanced I/Os and peripherals. The STM32L053x6/8 devices provide high power efficiency for a wide range of performance. It is achieved with a large choice of internal and external clock sources， an internal voltage adaptation and several low-power modes.

The STM32L053x6/8 devices offer several analog features， one 12-bit ADC with hardware oversampling， one DAC， two ultra-low-power comparators， several timers， one low-power timer （LPTIM）， three general-purpose 16-bit timers and one basic timer， one RTC and one SysTick which can be used as timebases. They also feature two watchdogs， one watchdog with independent clock and window capability and one window watchdog based on bus clock. Moreover， the STM32L053x6/8 devices embed standard and advanced communication interfaces： up to two I2C， two SPIs， one I2S， two USARTs， a low-power UART （LPUART）， and a crystal-less USB. The devices offer up to 24 capacitive sensing channels to simply add touch sensing functionality to any application. The STM32L053x6/8 also include a real-time clock and a set of backup registers that remain powered in Standby mode. Finally， their integrated LCD controller has a built-in LCD voltage generator that allows to drive up to 8 multiplexed LCDs with contrast independent of the supply voltage. The ultra-low-power STM32L053x6/8 devices operate from a 1.8 to 3.6 V power supply （down to 1.65 V at power down） with BOR and from a 1.65 to 3.6 V power supply without BOR option. They are available in the -40 to +125 ℃ temperature range.A comprehensive set of power-saving modes allows the design of low-power applications.

STM32L053R8主要特性：

? Ultra-low-power platform

– 1.65 V to 3.6 V power supply

– -40 to 125 ℃ temperature range

– 0.27 μA Standby mode （2 wakeup pins）

– 0.4 μA Stop mode （16 wakeup lines）

– 0.8 μA Stop mode + RTC + 8 KB RAM retention

– 88 μA/MHz in Run mode –3.5 μs wakeup time （from RAM）

– 5 μs wakeup time （from Flash memory）

? Core： Arm? 32-bit Cortex?-M0+ with MPU

– From 32 kHz up to 32 MHz max.

– 0.95 DMIPS/MHz

? Memories

– Up to 64 KB Flash memory with ECC

– 8KB RAM

– 2 KB of data EEPROM with ECC

– 20-byte backup register

– Sector protection against R/W operation

? Up to 51 fast I/Os （45 I/Os 5V tolerant）

? Reset and supply management

– Ultra-safe， low-power BOR （brownout reset） with 5 selectable thresholds

– Ultra-low-power POR/PDR

– Programmable voltage detector （PVD）

? Clock sources

– 1 to 25 MHz crystal oscillator

– 32 kHz oscillator for RTC with calibration

– High speed internal 16 MHz factory-trimmed RC （+/- 1%）

– Internal low-power 37 kHz RC

– Internal multispeed low-power 65 kHz to 4.2 MHz RC

– PLL for CPU clock

? Pre-programmed bootloader

– USART， SPI supported

? Development support

– Serial wire debug supported

? LCD driver for up to 8×28segments

– Support contrast adjustment

– Support blinking mode

– Step-up converted on board

? Rich Analog peripherals

– 12-bit ADC 1.14 Msps up to 16 channels （down to 1.65 V）

– 12-bit 1 channel DAC with output buffers （down to 1.8 V）

– 2x ultra-low-power comparators （window mode and wake up capability， down to 1.65 V）

? Up to 24 capacitive sensing channels supporting touchkey， linear and rotary touch sensors

? 7-channel DMA controller， supporting ADC， SPI， I2C， USART， DAC， Timers

? 8x peripheral communication interfaces

– 1x USB 2.0 crystal-less， battery charging detection and LPM

– 2x USART （ISO 7816， IrDA）， 1x UART （low power）

– Up to 4x SPI 16 Mbits/s

– 2x I2C （SMBus/PMBus）

? 9x timers： 1x 16-bit with up to 4 channels， 2x 16-bit with up to 2 channels， 1x 16-bit ultra-low-power timer， 1x SysTick， 1x RTC， 1x 16-bit basic for DAC， and 2x watchdogs （independent/window）

? CRC calculation unit， 96-bit unique ID

? True RNG and firewall protection

? All packages are ECOPACK?2

圖1.STM32L053x6/8框圖

圖2.STM32L053x6/8時鐘樹

評估板P-NUCLEO-IKA02A1

The P-NUCLEO-IKA02A1 evaluation pack provides a reference design for various electrochemical sensors.

The STM32 Nucleo gas expansion board interfaces electrochemical sensors with the MCU on the STM32 Nucleo development board. Two TSU111 operational amplifiers provide signal conditioning; they are ideal for electrochemical sensing thanks to their high precision and low power consumption. The expansion board includes an ultra-low current precision analog temperature sensor STLM20 used for compensation of gas readings.

STM32 Nucleo boards provide an affordable and flexible way for users to experiment with new ideas and build prototypes with any STM32 microcontroller line. The NUCLEO-L053R8 is designed for low power applications.

The design and componentry are optimised for battery operation and maximum battery life time.

圖3.評估板P-NUCLEO-IKA02A1外形圖

The P-NUCLEO-IKA02A1 evaluation pack targets a segment of CO detectors for home alarm systems. It is designed to be easily customized and meets EN50291 requirements.

評估板P-NUCLEO-IKA02A1主要特性：

? STM32 Nucleo gas expansion board

? compatible with most electrochemical sensors

? four different footprints for sensors （PCD13，5， PCD17， Mini and TGS5141）

? two-， three- and four-electrode sensors

? signal conditioning with TSU111

? STLM20 temperature sensor

? changeable gain

? NUCLEO-L053R8

? Ultra-low-power ARM? Cortex?-M0+ MCU （32 MHz max.） with 64 Kbytes Flash and 8 Kbytes of SRAM

? Carbon monoxide sensor

? Figaro TGS5141

? coin-cell sensor

? expected life time 》 10 yrs

? can pass 5000 ppm EN50291

? Low power design for long battery life

? RoHS compliant

圖4.評估板P-NUCLEO-IKA02A1一氧化碳電化學傳感器

圖5.評估板P-NUCLEO-IKA02A1擴展板：氣體信號調理電路圖

圖6.評估板P-NUCLEO-IKA02A1擴展板電路圖

評估板P-NUCLEO-IKA02A1材料清單：