Benchmark for esp-idf i2c driver.
A new i2c driver is now available in ESP-IDF V5.2.
The previous i2c driver is still available as a Legacy driver.
We measured the performance of New i2c driver and Legacy i2c driver.
I used this library as a reference.
Thank you UncleRus.
ESP-IDF V5.2.
This version can use both Legacy and New drivers.
MCP23017 16-Bit I/O Expander with i2c Interface.
We measured the time required to turn the GPA0 port ON/OFF 10,000 times using the test circuit below.
git clone https://github.com/nopnop2002/esp-idf-i2c-benchmark
cd esp-idf-i2c-benchmark/
idf.py set-target {esp32/esp32s2/esp32s3/esp32c2/esp32c3/esp32c6/esp32h2}
idf.py menuconfig
idf.py flash
The maximum I2C Clock frequency for the ESP32 i2c driver is 1.0MHz, but the ESP32C2, C3, and H2 do not work properly at 1MHz.
For any SoCs, the New Driver achieved faster results than the Legacy Driver.
| SoC@CPU Freq | i2c Clock Freq[MHz] | Legacy Driver[MillSec] | New Driver[MillSec] | |
|---|---|---|---|---|
| ESP32@160 | 1.0 | 9420 | 6540 | |
| ESP32@240 | 1.0 | 7060 | 5290 | |
| ESP32S2@160 | 1.0 | 7420 | 4450 | |
| ESP32S2@240 | 1.0 | 5790 | 3830 | |
| ESP32S3@160 | 1.0 | 8700 | 5240 | |
| ESP32S3@240 | 1.0 | 6720 | 4450 | |
| ESP32C2@120 | 0.6 | 8890 | 5520 | 26MHz XTAL |
| ESP32C3@160 | 0.9 | 6550 | 3880 | |
| ESP32C6@160 | 1.0 | 6490 | 3850 | |
| ESP32H2@96 | 0.8 | 10150 | 5430 |
ESP32C6 gave the fastest results when the CPU frequency was 160MHz (120MHz or 96MHz for some SoCs).
ESP32S2 gave the fastest results when the CPU frequency was 240MHz.
ESP32S2@240 gave the fastest results when the Legacy i2c driver.
ESP32S2@240 gave the fastest results when the New i2c driver.
However, ESP32C6@160 is the next fastest.
There are only a few differences between ESP32S2@240(3830) and ESP32C6@160(3850).
Legacy driver
$ idf.py size
Total sizes:
Used static DRAM: 11040 bytes ( 169696 remain, 6.1% used)
.data size: 8808 bytes
.bss size: 2232 bytes
Used static IRAM: 56426 bytes ( 74646 remain, 43.0% used)
.text size: 55399 bytes
.vectors size: 1027 bytes
Used Flash size : 130971 bytes
.text: 87651 bytes
.rodata: 43064 bytes
Total image size: 196205 bytes (.bin may be padded larger)
New driver
$ idf.py size
Total sizes:
Used static DRAM: 11000 bytes ( 169736 remain, 6.1% used)
.data size: 8760 bytes
.bss size: 2240 bytes
Used static IRAM: 52362 bytes ( 78710 remain, 39.9% used)
.text size: 51335 bytes
.vectors size: 1027 bytes
Used Flash size : 135771 bytes
.text: 92471 bytes
.rodata: 43044 bytes
Total image size: 196893 bytes (.bin may be padded larger)
Note:
Please note that this benchmark is a result of maximum i2c clock frequency.
This result may be different if the i2c clock frequency is lower.
Note:
The difference in stack size used between Legacy and New drivers is not clear.