Esp32 monitors the battery voltage with ULP when the battery is powered

Chen Tuo 2022/06/01-2022/06/01

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

and 《ESP32 - ULP The coprocessor reads the on-chip Hall sensor in low-power mode HALL SENSOR》

https://zhuanlan.zhihu.com/p/522082909

https://blog.csdn.net/chentuo2000/article/details/125048580?spm=1001.2014.3001.5502

In two articles we discussed ESP32 stay deep sleep Current in mode , In this article, we test based on official routines ESP32 When the battery is powered ULP Monitor battery voltage .

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

2. Official documents

• Official routine

《ULP Coprocessor Detect ESP32 Brownout》

https://gitee.com/chentuo2000/esp-iot-solution/tree/release/v1.1/examples/ulp_examples/ulp_detect_brownout

This example utilizes ULP Coprocessor ADC Measurement function , Polling in the background to detect VDD33 The voltage value of the pin , And deal with it when the voltage is unstable .

• Hardware connection

In this case , choice SAR ADC1 Of the 7 passageway （GPIO34）, Through external jumpers , Connected to VDD33 Pin for voltage measurement , Test the use of the circuit board 《ESP32 How is the deep sleep current lower than 10uA》 The board introduced in the article .

For details, please refer to  ESP32 Technical manual

https://www.espressif.com.cn/sites/default/files/documentation/esp32_technical_reference_manual_en.pdf

• How software works

Lord CPU After non sleep mode is activated , The following settings are required ：

1) To configure SAR ADC1, And enable ULP Access to its functions

2) Initialize and enable RTC Watchdog timer

3) Load and start ULP Program

ULP After the program starts, it will always poll for detection VDD33 The voltage value of the pin ：

1) If the voltage value is lower than the programmed value Brownout threshold , Turn off the digital kernel , RF circuits , And stop CPU

2) If the voltage value rises from low to set Brownout threshold ,ULP adopt RTC WDT Timeout resets the entire system

Be careful ： because ULP Modules that do not have access to the digital part , Therefore, it cannot be read EFUSE Medium ADC Calibrate parameters to SAR ADC1 Calibrate the measurement results , So finally SAR ADC1 There will be some deviations in the measurement results of different module types .

ULP Coprocessors currently only support assembly development , The corresponding assembler is described in detail in the routine documentation .

• ESP-IoT-Solution brief introduction

The official routine is esp-iot-solution In the library .

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 experimental 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_detect_brownout/ ~/esp/

• Project tree

cd ulp_detect_brownout

 

• 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 ）

Lord CPU After starting , Print regularly ULP Read the VDD33 Pin voltage value （ADC Original value and converted voltage value ）.ULP The coprocessor is set to timing 100ms Wake up detection VDD33 Pin voltage value , In the example Brownout Threshold set to 2.76v.

The following is the running log of the program ：

 

4095 Is the measured value ,3.3 Is the converted voltage .