Esp32 - ULP coprocessor reading Hall sensor in low power mode

Chen Tuo 2022/05/26-2022/05/30

1. summary

stay 《ESP32 How is the deep sleep current lower than 10uA》

https://zhuanlan.zhihu.com/p/521640890

https://blog.csdn.net/chentuo2000/article/details/125033711?spm=1001.2014.3001.5502

In this article, we tested ESP32 stay deep sleep Only... Is used in mode RTC The current when , In this article, we will start again ULP Coprocessor , test RTC and ULP When opened deep sleep electric current .

about ESP32 The current under various working modes can be referred to 《 understand ESP32 Sleep mode and its power consumption 》 One article .

https://zhuanlan.zhihu.com/p/521885688

https://blog.csdn.net/chentuo2000/article/details/125042156?spm=1001.2014.3001.5502

• Hall sensor

According to the Hall effect , When the current passes perpendicular to the magnetic field N Type semiconductor , An additional electric field will be generated in the direction perpendicular to the current and magnetic field , Thus, a potential difference is formed at both ends of the semiconductor , The specific level is related to the intensity of the electromagnetic field and the size of the current . When a constant current passes through a magnetic field or a current exists in a constant magnetic field , Hall effect sensor can be used to measure magnetic field strength . Hall sensors are widely used , Including proximity detection 、 location 、 Speed measurement and current detection, etc .

• ESP32 There is a built-in Hall effect sensor , It can detect the change of the surrounding magnetic field .

In this paper, the experiment ESP32-ULP How the coprocessor reads chips in low power mode Hall sensor .

This example ULP Coprocessor every 3 Wake up once per second , After waking up, read the hall sensor value in low power consumption mode , adopt hall phase shift two , Read vp and vn Two values each, four values in total , Subtract the common mode part to get offset value , This value can be used to characterize the influence of the environment on the hall sensor .

2. Official documents

• Official routine

ULP The coprocessor reads the on-chip Hall sensor in low-power mode HALL SENSOR

https://github.com/espressif/esp-iot-solution/tree/release/v1.1/examples/ulp_examples/ulp_hall_sensor

You can see the official routine in esp-iot-solution In the library .

• ESP-IoT-Solution brief introduction

https://docs.espressif.com/projects/espressif-esp-iot-solution/zh_CN/latest/gettingstarted.html

 

• ESP-IoT-Solution edition

Different versions ESP-IoT-Solution The explanation is as follows ：

 

• ESP-IoT-Solution Programming Guide

https://docs.espressif.com/projects/espressif-esp-iot-solution/zh_CN/latest/index.html

 

3. obtain ESP-IoT-Solution

• Get orders

 

If from the official of Lexin github Library Download is difficult , You can start with gitee Clone a library on , And then from gitee Upload and download . Here is the download from my cloned Library , My library is private , You need to clone one yourself .

• Official routine

Be careful , The hall sensor routine is v1.1 In the version .

 

• download esp-iot-solution v1.1

cd ~/esp

git clone -b release/v1.1 --recursive https://gitee.com/chentuo2000/esp-iot-solution.git

 

from gitee When downloading clone library , The subject is going well , Having trouble downloading submodules , You need to manually download the following sub modules ：

 

Download manually according to the source and the corresponding installation path .

If you still can't download , You can download this from the link below 3 Sub module ：

download Adafruit-GFX-Library.tar.gz

https://download.csdn.net/download/chentuo2000/85481416

download ugfx.tar.gz

https://download.csdn.net/download/chentuo2000/85481491

download lvgl.tar.gz

https://download.csdn.net/download/chentuo2000/85481538

4. development environment

《 Use Lexin domestic Gitee Image building ESP32 development environment 》

https://zhuanlan.zhihu.com/p/348106034

https://blog.csdn.net/chentuo2000/article/details/113424934?spm=1001.2014.3001.5501

5. Build the project

• Copy official routine

Copy the official example project to ESP-IDF Beyond development tools ：

cd ~/esp

cp -r ~/esp/esp-iot-solution/examples/ulp_examples/ulp_hall_sensor ~/esp/

• Project tree

cd ulp_hall_sensor

 

• Refresh esp-idf Environmental Science

get_idf

Be careful ： Each time you open the terminal, enter sdk Execute this command once

• Set the target chip

idf.py set-target esp32

• Clear previous builds

idf.py fullclean

• Configuration items

idf.py menuconfig

1) Set up Flash The memory size is 4MB

 

2) ULP It is enabled by default

 

preservation , sign out .

• Compile the project

idf.py build

• Burn project

see USB Serial port COM slogan ：

 

burning ：

idf.py -p /dev/ttyS3 -b 115200 flash

• Enable monitor

idf.py monitor -p /dev/ttyS3

（Ctrl+] You can exit the monitor program ）

6. Sample test

This example ULP Coprocessor every 3S Wake up once , After waking up, read the hall sensor value in low power consumption mode , adopt hall phase shift two , Read vp and vn Two values each, four values in total , Subtract the common mode part to get offset value , This value can be used to characterize the influence of the environment on the hall sensor . Pictured , The first printed value is the hall sensor value measured when there is no strong magnetic field around ; The value printed for the second time is using a neodymium iron boron magnet N Very close ESP32 The value obtained when ; The value printed for the third time is that of NdFeB magnet S Very close ESP32 The value obtained when , It can be seen that the value of Hall sensor has changed greatly .

• The system starts the serial port output

There is no strong magnetic field around

 

magnetic N Very close ESP32

 

magnetic S Very close ESP32

 

• deep sleep electric current

 

and 《ESP32 How is the deep sleep current lower than 10uA》 In this article, only RTC Comparison ,deep sleep The current is about 2uA, Still less than 10uA.