espressif
AnalogRead has been quite slow since v1.0.4
Board
ESP32 Dev Module
Device Description
SparkFun ESP32 Thing
Hardware Configuration
Microphone on ESP pin 34
Version
v2.0.2
IDE Name
Arduino IDE
Operating System
Windows 10
Flash frequency
80 MHz
PSRAM enabled
no
Upload speed
921600
Description
I'm running an FFT on the signal from a microphone attached to pin 34 (compiling with ESP32 Dev Module) to drive some LEDs. However I've stripped all of that away and written a simple speed test for analogRead.
Running the attached sketch on ESP32 Core v1.0.4 completes 916632 loops in the first ten seconds, while running the same code on v2.0.2 only completes 117625 loops in the same amount of time. Is there a reason that analogRead() has been slowed down in versions >v1.0.4?
Sketch
#define TIME_BETWEEN_OUTPUTS 1000
unsigned long loopNumber = 0;
unsigned long timeSinceLastOutput;
unsigned long currentTime;
void setup() {
Serial.begin(115200);
Serial.println("Speed Test Start");
currentTime = millis();
timeSinceLastOutput = currentTime;
}
void loop() {
currentTime = millis();
if (currentTime - timeSinceLastOutput > TIME_BETWEEN_OUTPUTS)
{
timeSinceLastOutput = currentTime;
Serial.print(currentTime / 1000);
Serial.print("s: ");
Serial.println(loopNumber);
}
analogRead(34);
loopNumber++;
}
Debug Message
1s: 11754
2s: 23517
3s: 35281
4s: 47045
5s: 58809
6s: 70573
7s: 82335
8s: 94099
9s: 105863
Other Steps to Reproduce
No response
I have checked existing issues, online documentation and the Troubleshooting Guide
- [X] I confirm I have checked existing issues, online documentation and Troubleshooting guide.
v2.0.3-rc1 is slow too. On my ESP-WROOM-32, 100000 analogRead's on pin 36 (ADC1 - channel 0) average 87 uSec using 2.0.3-rc1 and only 9 uSec using 1.0.4
@VojtechBartoska It might be worthwhile to include the old analogRead from 1.0.x as an analogReadLegacy function, which will only work on esp32, but will have the speed of the old direct register peeks.
@randymortensen You can copy the old esp32-hal-adc.c and .h from 1.0.4 (or 1.0.6) into your
Overwriting those files in 2.0.3-rc1 with the ones from 1.0.4 did improve the averaged analogRead time (using the same code as before) to 24 uSec. (Of course, I was hoping for 9 uSec :-)
For kicks I did a further experiment by overwriting those files in platformio which uses the 2.0.1 core. This resulted in 15 uSec per analogRead which is shorter than the 24 uSec I found in Arduino IDE with 2.0.3-rc1.
thanks @randymortensen and @lbernstone for your feedback. I'm adding this issue to our Roadmap and we will investigate this further.
Hi, I can confirm that with the commit https://github.com/espressif/arduino-esp32/commit/d8b209846131119ad6a84af5987e8625f37900df the speed lowered. The question of getting it back, or having both versions at a time might not be so simple.
We can not go back to use our own driver for analogRead, because there are differences in the ADC between the chips and that would cause a nightmare to support. ESP-IDF's team has already done all that work and do provide support for the feature.
