- Why do we need this ESP32_S2_ISR_Servo library
- Changelog
- Prerequisites
- Installation
- HOWTO Fix
Multiple DefinitionsLinker Error - HOWTO Use analogRead() with ESP32 running WiFi and/or BlueTooth (BT/BLE)
- More useful Information
- HOWTO Usage
- Examples
- Example ESP32_S2_ISR_MultiServos
- Debug Terminal Output Samples
- Debug
- Troubleshooting
- Releases
- Issues
- TO DO
- DONE
- Contributions and Thanks
- Contributing
- License
- Copyright
Why do we need this ESP32_S2_ISR_Servo library
Imagine you have a system with a mission-critical function controlling a robot arm or doing something much more important. You normally use a software timer to poll, or even place the function in loop(). But what if another function is blocking the loop() or setup().
So your function might not be executed, and the result would be disastrous.
You'd prefer to have your function called, no matter what happening with other functions (busy loop, bug, etc.).
The correct choice is to use a Hardware Timer with Interrupt to call your function.
These hardware timers, using interrupt, still work even if other functions are blocking. Moreover, they are much more precise (certainly depending on clock frequency accuracy) than other software timers using millis() or micros(). That's necessary if you need to measure some data requiring better accuracy.
Functions using normal software timers, relying on loop() and calling millis(), won't work if the loop() or setup() is blocked by certain operation. For example, certain function is blocking while it's connecting to WiFi or some services.
This library enables you to use 1 Hardware Timer on an ESP32_S2-based board to control up to 16 independent servo motors.
-
Inside the attached function,
delay()won’t work and the value returned bymillis()will not increment. Serial data received while in the function may be lost. You should declare as volatile any variables that you modify within the attached function. -
Typically global variables are used to pass data between an ISR and the main program. To make sure variables shared between an ISR and the main program are updated correctly, declare them as volatile.
-
Avoid using
Serial.print()-related functions inside ISR. Just for temporary debug purpose, but even this also can crash the system any time. Beware. -
Your functions are now part of ISR (Interrupt Service Routine), and must be
lean / mean, and follow certain rules. More to read on:
This ESP32_S2_ISR_Servo library currently supports these following boards:
- ESP32_S2-based boards, such as
ESP32S2_DEV,ESP32_S2 Saola, Adafruit QTPY_ESP32S2, etc.
Arduino IDE 1.8.19+for Arduino.ESP32 Core 2.0.5+for ESP32-based boards.
The best and easiest way is to use Arduino Library Manager. Search for ESP32_S2_ISR_Servo, then select / install the latest version.
You can also use this link
Another way to install is to:
- Navigate to ESP32_S2_ISR_Servo page.
- Download the latest release
ESP32_S2_ISR_Servo-main.zip. - Extract the zip file to
ESP32_S2_ISR_Servo-maindirectory - Copy whole
ESP32_S2_ISR_Servo-mainfolder to Arduino libraries' directory such as~/Arduino/libraries/.
- Install VS Code
- Install PlatformIO
- Install ESP32_S2_ISR_Servo library by using Library Manager. Search for ESP32_S2_ISR_Servo in Platform.io Author's Libraries
- Use included platformio.ini file from examples to ensure that all dependent libraries will installed automatically. Please visit documentation for the other options and examples at Project Configuration File
The current library implementation, using xyz-Impl.h instead of standard xyz.cpp, possibly creates certain Multiple Definitions Linker error in certain use cases.
You can include this .hpp file
// Can be included as many times as necessary, without `Multiple Definitions` Linker Error
#include "ESP32_S2_ISR_Servo.hpp" //https://github.com/khoih-prog/ESP32_S2_ISR_Servoin many files. But be sure to use the following .h file in just 1 .h, .cpp or .ino file, which must not be included in any other file, to avoid Multiple Definitions Linker Error
// To be included only in main(), .ino with setup() to avoid `Multiple Definitions` Linker Error
#include "ESP32_S2_ISR_Servo.h" //https://github.com/khoih-prog/ESP32_S2_ISR_ServoCheck the new multiFileProject example for a HOWTO demo.
Have a look at the discussion in Different behaviour using the src_cpp or src_h lib #80
Please have a look at ESP_WiFiManager Issue 39: Not able to read analog port when using the autoconnect example to have more detailed description and solution of the issue.
ADC1controls ADC function for pins GPIO32-GPIO39ADC2controls ADC function for pins GPIO0, 2, 4, 12-15, 25-27
Look in file adc_common.c
In
ADC2, there're two locks used for different cases:
lock shared with app and Wi-Fi: ESP32: When Wi-Fi using the
ADC2, we assume it will never stop, so app checks the lock and returns immediately if failed. ESP32S2: The controller's control over the ADC is determined by the arbiter. There is no need to control by lock.lock shared between tasks: when several tasks sharing the
ADC2, we want to guarantee all the requests will be handled. Since conversions are short (about 31us), app returns the lock very soon, we use a spinlock to stand there waiting to do conversions one by one.adc2_spinlock should be acquired first, then adc2_wifi_lock or rtc_spinlock.
- In order to use
ADC2for other functions, we have to acquire complicated firmware locks and very difficult to do - So, it's not advisable to use
ADC2with WiFi/BlueTooth (BT/BLE). - Use
ADC1, and pinsGPIO32-GPIO39 - If somehow it's a must to use those pins serviced by
ADC2(GPIO0, 2, 4, 12, 13, 14, 15, 25, 26 and 27), use the fix mentioned at the end of ESP_WiFiManager Issue 39: Not able to read analog port when using the autoconnect example to work with ESP32 WiFi/BlueTooth (BT/BLE).
- The ESP32 has two timer groups, each one with two general purpose hardware timers.
- All the timers are based on 64-bit counters and 16-bit prescalers.
- The timer counters can be configured to count up or down and support automatic reload and software reload.
- They can also generate alarms when they reach a specific value, defined by the software.
- The value of the counter can be read by the software program.
// returns last position in degrees if success, or -1 on wrong servoIndex
int getPosition(unsigned servoIndex);
// returns pulseWidth in microsecs (within min/max range) if success, or 0 on wrong servoIndex
unsigned int getPulseWidth(unsigned servoIndex);What special in this ESP32_S2_ISR_Servo library
Now these new 16 ISR-based Servo controllers just use one ESP32 Hardware Timer. The number 16 is just arbitrarily chosen, and depending on application, you can increase that number to 32, 48, etc. without problem.
The accuracy is nearly perfect compared to software timers. The most important feature is they're ISR-based timers
Therefore, their executions are not blocked by bad-behaving functions / tasks. This important feature is absolutely necessary for mission-critical tasks.
The MultipleServos example, which controls 6 servos independently, will demonstrate the nearly perfect accuracy. Being ISR-based servo controllers, their executions are not blocked by bad-behaving functions / tasks, such as connecting to WiFi, Internet and Blynk services.
This non-being-blocked important feature is absolutely necessary for mission-critical tasks.
You'll see blynkTimer Software is blocked while system is connecting to WiFi / Internet / Blynk, as well as by blocking task in loop(), using delay() function as an example. The elapsed time then is very unaccurate
How to use:
#define TIMER_INTERRUPT_DEBUG 1
#define ISR_SERVO_DEBUG 1
// Select different ESP32 timer number (0-3) to avoid conflict
#define USE_ESP32_TIMER_NO 3
#include "ESP32_S2_ISR_Servo.h"
//See file .../hardware/espressif/esp32/variants/(esp32|doitESP32devkitV1)/pins_arduino.h
#define PIN_LED 2 // Pin D2 mapped to pin GPIO2/ADC12 of ESP32, control on-board LED
#define PIN_D0 0 // Pin D0 mapped to pin GPIO0/BOOT/ADC11/TOUCH1 of ESP32
#define PIN_D1 1 // Pin D1 mapped to pin GPIO1/TX0 of ESP32
#define PIN_D2 2 // Pin D2 mapped to pin GPIO2/ADC12/TOUCH2 of ESP32
#define PIN_D3 3 // Pin D3 mapped to pin GPIO3/RX0 of ESP32
#define PIN_D4 4 // Pin D4 mapped to pin GPIO4/ADC10/TOUCH0 of ESP32
#define PIN_D5 5 // Pin D5 mapped to pin GPIO5/SPISS/VSPI_SS of ESP32
#define PIN_D6 6 // Pin D6 mapped to pin GPIO6/FLASH_SCK of ESP32
#define PIN_D7 7 // Pin D7 mapped to pin GPIO7/FLASH_D0 of ESP32
#define PIN_D8 8 // Pin D8 mapped to pin GPIO8/FLASH_D1 of ESP32
#define PIN_D9 9 // Pin D9 mapped to pin GPIO9/FLASH_D2 of ESP32
#define PIN_D10 10 // Pin D10 mapped to pin GPIO10/FLASH_D3 of ESP32
#define PIN_D11 11 // Pin D11 mapped to pin GPIO11/FLASH_CMD of ESP32
#define PIN_D12 12 // Pin D12 mapped to pin GPIO12/HSPI_MISO/ADC15/TOUCH5/TDI of ESP32
#define PIN_D13 13 // Pin D13 mapped to pin GPIO13/HSPI_MOSI/ADC14/TOUCH4/TCK of ESP32
#define PIN_D14 14 // Pin D14 mapped to pin GPIO14/HSPI_SCK/ADC16/TOUCH6/TMS of ESP32
#define PIN_D15 15 // Pin D15 mapped to pin GPIO15/HSPI_SS/ADC13/TOUCH3/TDO of ESP32
#define PIN_D16 16 // Pin D16 mapped to pin GPIO16/TX2 of ESP32
#define PIN_D17 17 // Pin D17 mapped to pin GPIO17/RX2 of ESP32
#define PIN_D18 18 // Pin D18 mapped to pin GPIO18/VSPI_SCK of ESP32
#define PIN_D19 19 // Pin D19 mapped to pin GPIO19/VSPI_MISO of ESP32
#define PIN_D21 21 // Pin D21 mapped to pin GPIO21/SDA of ESP32
#define PIN_D22 22 // Pin D22 mapped to pin GPIO22/SCL of ESP32
#define PIN_D23 23 // Pin D23 mapped to pin GPIO23/VSPI_MOSI of ESP32
#define PIN_D24 24 // Pin D24 mapped to pin GPIO24 of ESP32
#define PIN_D25 25 // Pin D25 mapped to pin GPIO25/ADC18/DAC1 of ESP32
#define PIN_D26 26 // Pin D26 mapped to pin GPIO26/ADC19/DAC2 of ESP32
#define PIN_D27 27 // Pin D27 mapped to pin GPIO27/ADC17/TOUCH7 of ESP32
#define PIN_D32 32 // Pin D32 mapped to pin GPIO32/ADC4/TOUCH9 of ESP32
#define PIN_D33 33 // Pin D33 mapped to pin GPIO33/ADC5/TOUCH8 of ESP32
#define PIN_D34 34 // Pin D34 mapped to pin GPIO34/ADC6 of ESP32
#define PIN_D35 35 // Pin D35 mapped to pin GPIO35/ADC7 of ESP32
#define PIN_D36 36 // Pin D36 mapped to pin GPIO36/ADC0/SVP of ESP32
#define PIN_D39 39 // Pin D39 mapped to pin GPIO39/ADC3/SVN of ESP32
#define PIN_RX0 3 // Pin RX0 mapped to pin GPIO3/RX0 of ESP32
#define PIN_TX0 1 // Pin TX0 mapped to pin GPIO1/TX0 of ESP32
#define PIN_SCL 22 // Pin SCL mapped to pin GPIO22/SCL of ESP32
#define PIN_SDA 21 // Pin SDA mapped to pin GPIO21/SDA of ESP32
// Published values for SG90 servos; adjust if needed
#define MIN_MICROS 800 //544
#define MAX_MICROS 2450
int servoIndex1 = -1;
int servoIndex2 = -1;
void setup()
{
Serial.begin(115200);
while (!Serial && millis() < 5000);
delay(500);
Serial.print(F("\nStarting ISR_MultiServos on "));
Serial.println(ARDUINO_BOARD);
Serial.println(ESP32_S2_ISR_SERVO_VERSION);
//Select ESP32 timer USE_ESP32_TIMER_NO
ESP32_ISR_Servos.useTimer(USE_ESP32_TIMER_NO);
servoIndex1 = ESP32_ISR_Servos.setupServo(PIN_D5, MIN_MICROS, MAX_MICROS);
servoIndex2 = ESP32_ISR_Servos.setupServo(PIN_D6, MIN_MICROS, MAX_MICROS);
if (servoIndex1 != -1)
Serial.println(F("Setup Servo1 OK"));
else
Serial.println(F("Setup Servo1 failed"));
if (servoIndex2 != -1)
Serial.println(F("Setup Servo2 OK"));
else
Serial.println(F("Setup Servo2 failed"));
}
void loop()
{
int position;
if ( ( servoIndex1 != -1) && ( servoIndex2 != -1) )
{
for (position = 0; position <= 180; position++)
{
// goes from 0 degrees to 180 degrees
// in steps of 1 degree
if (position % 30 == 0)
{
Serial.print(F("Servo1 pos = "));
Serial.print(position);
Serial.print(F(", Servo2 pos = "));
Serial.println(180 - position);
}
ESP32_ISR_Servos.setPosition(servoIndex1, position);
ESP32_ISR_Servos.setPosition(servoIndex2, 180 - position);
// waits 30ms for the servo to reach the position
delay(30);
}
delay(5000);
for (position = 180; position >= 0; position--)
{
// goes from 180 degrees to 0 degrees
if (position % 30 == 0)
{
Serial.print(F("Servo1 pos = "));
Serial.print(position);
Serial.print(F(", Servo2 pos = "));
Serial.println(180 - position);
}
ESP32_ISR_Servos.setPosition(servoIndex1, position);
ESP32_ISR_Servos.setPosition(servoIndex2, 180 - position);
// waits 30ms for the servo to reach the position
delay(30);
}
delay(5000);
}
}- ESP32_S2_ISR_MultiServos
- ESP32_S2_MultipleRandomServos
- ESP32_S2_MultipleServos
- ISR_MultiServos
- MultipleRandomServos
- MultipleServos
- multiFileProject New
Example ESP32_S2_ISR_MultiServos
1. File ESP32_S2_ISR_MultiServos.ino
Starting ESP32_S2_MultipleRandomServos on ESP32S2_DEV
ESP32_S2_ISR_Servo v1.2.0
[ISR_SERVO] ESP32_S2_FastTimerInterrupt: _timerNo = 3 , _fre = 1000000
[ISR_SERVO] TIMER_BASE_CLK = 80000000 , TIMER_DIVIDER = 80
[ISR_SERVO] _timerIndex = 1 , _timerGroup = 1
[ISR_SERVO] _count = 0 - 10
[ISR_SERVO] timer_set_alarm_value = 10.00
[ISR_SERVO] Starting ITimer OK
Setup OK Servo index = 0
Setup OK Servo index = 1
Setup OK Servo index = 2
Setup OK Servo index = 3
Setup OK Servo index = 4
Setup OK Servo index = 5
Servos @ 0 degree
Servos idx = 0, act. pos. (deg) = [ISR_SERVO] Idx = 0
[ISR_SERVO] cnt = 80 , pos = 0
0, pulseWidth (us) = [ISR_SERVO] Idx = 0
[ISR_SERVO] cnt = 80 , pos = 0
800
Servos idx = 1, act. pos. (deg) = [ISR_SERVO] Idx = 1
[ISR_SERVO] cnt = 80 , pos = 0
0, pulseWidth (us) = [ISR_SERVO] Idx = 1
[ISR_SERVO] cnt = 80 , pos = 0
800
Servos idx = 2, act. pos. (deg) = [ISR_SERVO] Idx = 2
[ISR_SERVO] cnt = 80 , pos = 0
0, pulseWidth (us) = [ISR_SERVO] Idx = 2
[ISR_SERVO] cnt = 80 , pos = 0
800
Servos idx = 3, act. pos. (deg) = [ISR_SERVO] Idx = 3
[ISR_SERVO] cnt = 80 , pos = 0
0, pulseWidth (us) = [ISR_SERVO] Idx = 3
[ISR_SERVO] cnt = 80 , pos = 0
800
Servos idx = 4, act. pos. (deg) = [ISR_SERVO] Idx = 4
[ISR_SERVO] cnt = 80 , pos = 0
0, pulseWidth (us) = [ISR_SERVO] Idx = 4
[ISR_SERVO] cnt = 80 , pos = 0
800
Servos idx = 5, act. pos. (deg) = [ISR_SERVO] Idx = 5
[ISR_SERVO] cnt = 80 , pos = 0
0, pulseWidth (us) = [ISR_SERVO] Idx = 5
[ISR_SERVO] cnt = 80 , pos = 0
800
Servos @ 90 degree
Servos idx = 0, act. pos. (deg) = [ISR_SERVO] Idx = 0
[ISR_SERVO] cnt = 162 , pos = 90
90, pulseWidth (us) = [ISR_SERVO] Idx = 0
[ISR_SERVO] cnt = 162 , pos = 90
1620
Servos idx = 1, act. pos. (deg) = [ISR_SERVO] Idx = 1
[ISR_SERVO] cnt = 162 , pos = 90
90, pulseWidth (us) = [ISR_SERVO] Idx = 1
[ISR_SERVO] cnt = 162 , pos = 90
1620
Servos idx = 2, act. pos. (deg) = [ISR_SERVO] Idx = 2
[ISR_SERVO] cnt = 162 , pos = 90
90, pulseWidth (us) = [ISR_SERVO] Idx = 2
[ISR_SERVO] cnt = 162 , pos = 90
1620
Servos idx = 3, act. pos. (deg) = [ISR_SERVO] Idx = 3
[ISR_SERVO] cnt = 162 , pos = 90
90, pulseWidth (us) = [ISR_SERVO] Idx = 3
[ISR_SERVO] cnt = 162 , pos = 90
1620
Servos idx = 4, act. pos. (deg) = [ISR_SERVO] Idx = 4
[ISR_SERVO] cnt = 162 , pos = 90
90, pulseWidth (us) = [ISR_SERVO] Idx = 4
[ISR_SERVO] cnt = 162 , pos = 90
1620
Servos idx = 5, act. pos. (deg) = [ISR_SERVO] Idx = 5
[ISR_SERVO] cnt = 162 , pos = 90
90, pulseWidth (us) = [ISR_SERVO] Idx = 5
[ISR_SERVO] cnt = 162 , pos = 90
1620
Servos @ 180 degree
Servos idx = 0, act. pos. (deg) = [ISR_SERVO] Idx = 0
[ISR_SERVO] cnt = 245 , pos = 180
180, pulseWidth (us) = [ISR_SERVO] Idx = 0
[ISR_SERVO] cnt = 245 , pos = 180
2450
Servos idx = 1, act. pos. (deg) = [ISR_SERVO] Idx = 1
[ISR_SERVO] cnt = 245 , pos = 180
180, pulseWidth (us) = [ISR_SERVO] Idx = 1
[ISR_SERVO] cnt = 245 , pos = 180
2450
Servos idx = 2, act. pos. (deg) = [ISR_SERVO] Idx = 2
[ISR_SERVO] cnt = 245 , pos = 180
180, pulseWidth (us) = [ISR_SERVO] Idx = 2
[ISR_SERVO] cnt = 245 , pos = 180
2450
Servos idx = 3, act. pos. (deg) = [ISR_SERVO] Idx = 3
[ISR_SERVO] cnt = 245 , pos = 180
180, pulseWidth (us) = [ISR_SERVO] Idx = 3
[ISR_SERVO] cnt = 245 , pos = 180
2450
Servos idx = 4, act. pos. (deg) = [ISR_SERVO] Idx = 4
[ISR_SERVO] cnt = 245 , pos = 180
180, pulseWidth (us) = [ISR_SERVO] Idx = 4
[ISR_SERVO] cnt = 245 , pos = 180
2450
Servos idx = 5, act. pos. (deg) = [ISR_SERVO] Idx = 5
[ISR_SERVO] cnt = 245 , pos = 180
180, pulseWidth (us) = [ISR_SERVO] Idx = 5
[ISR_SERVO] cnt = 245 , pos = 180
2450
Servos sweeps from 0-180 degrees
Starting ESP32_S2_ISR_MultiServos on ESP32S2_DEV
ESP32_S2_ISR_Servo v1.2.0
[ISR_SERVO] ESP32_S2_FastTimerInterrupt: _timerNo = 3 , _fre = 1000000
[ISR_SERVO] TIMER_BASE_CLK = 80000000 , TIMER_DIVIDER = 80
[ISR_SERVO] _timerIndex = 1 , _timerGroup = 1
[ISR_SERVO] _count = 0 - 10
[ISR_SERVO] timer_set_alarm_value = 10.00
[ISR_SERVO] Starting ITimer OK
Setup Servo1 OK
Setup Servo2 OK
Servo1 pos = 0, Servo2 pos = 180
Servo1 pos = 30, Servo2 pos = 150
Servo1 pos = 60, Servo2 pos = 120
Servo1 pos = 90, Servo2 pos = 90
Servo1 pos = 120, Servo2 pos = 60
Servo1 pos = 150, Servo2 pos = 30
Servo1 pos = 180, Servo2 pos = 0
Debug is enabled by default on Serial.
You can also change the debugging level from 0 to 2. Be careful and using level 2 only for temporary debug purpose only.
#define TIMER_INTERRUPT_DEBUG 1
#define ISR_SERVO_DEBUG 1If you get compilation errors, more often than not, you may need to install a newer version of the core for Arduino boards.
Sometimes, the library will only work if you update the board core to the latest version because I am using newly added functions.
Submit issues to: ESP32_S2_ISR_Servo issues
- Search for bug and improvement.
- Similar features for Arduino (UNO, Mega, etc...), ESP32 and ESP8266
- Add functions
getPosition()andgetPulseWidth() - Optimize the code
- Add more complicated examples
- Convert to
h-onlylibrary. - Optimize library code by using
reference-passinginstead ofvalue-passing - Improve accuracy by using
float, instead ofuint32_tforpositionin degrees - Add example multiFileProject to demo for multiple-file project
- Suppress errors and warnings for new ESP32 core
v2.0.5 - Use
allman astyleand addutils
Many thanks for everyone for bug reporting, new feature suggesting, testing and contributing to the development of this library. Especially to these people who have directly or indirectly contributed to this ESP32_S2_ISR_Servo library
If you want to contribute to this project:
- Report bugs and errors
- Ask for enhancements
- Create issues and pull requests
- Tell other people about this library
- The library is licensed under MIT
Copyright (C) 2021- Khoi Hoang
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