ESP32 News

ESP32-S2 vs ESP32

Espressif announced recently that the mass production for the new ESP32-S2 will start in February 2020. Compared to the well known ESP32, ESP32-S2 brings some advantages in terms of power consumption and performance, but it lacks some important hardware features like Bluetooth or dual-core CPU.

Espressif also announced that in 2020 is planning to launch 4 new chips to cover different segments of the market. There is not much information about these, but it’s nice to see the effort this company puts into becoming a leader in IoT chips manufacturing.

ESP32-S2 overview

ESP32-S2 is designed to be a low power WiFi SoC solution for IoT and smart-home devices. It comes with enhanced encryption capabilities and improved radio performance.

ESP32-S2 block diagram
ESP32-S2 block diagram (source ESP32-S2 datasheet)

While limiting the connectivity features (WiFi only, no bluetooth support), Espressif was able to add a bunch of extra peripherals for human-machine interaction like builtin camera and LCD interfaces. These will be much needed for the development of wide range of applications, from smart-home devices to industrial automation.

Processor and memory

ESP32-S2 comes with a 240 MHz Xtensa® 32-bit LX7 single-core processor with 320 KB of SRAM and 128 KB of ROM. The performance of this CPU should be similar with the one of the ESP32, but much more energy efficient.

ESP32 vs ESP32-S2 MCU and memory comparaison
Feature ESP32 ESP32-S2
CPU Xtensa® 32-bit LX6 Xtensa® 32-bit LX7
Cores 2 1
Frequency 240 MHz 240MHz
ROM memory 448 KB 128 KB
SRAM memory 520 KB 320 KB
RTC SRAM memory 8 KB 8 KB
eFuse memory 1 Kbit 4 Kbit

Power consumption

ESP32-S2 is much more energy efficient than ESP32, in both CPU power consumption as well as RF power consumption. In some cases, ESP32-S2 is more than 50% more efficient than ESP32. However, the peak RF power consumption of ESP32-S2 is still unsuited to run on normal batteries. The peak RF usage is way above of what a normal battery pack can handle.

ESP32 vs ESP32-S2 power consumption
Work mode Testing condition ESP32 ESP32-S2
Modem-sleep (CPU is ON) 240 MHz 30 mA ~ 68 mA 19 mA
160 MHz 27 mA ~ 44 mA 16 mA
80 MHz 20 mA ~ 31 mA 12 mA
Light-sleep 800 μA 450 μA
Deep-sleep  ULP is ON 150 μA 220 μA
ULP sensor-monitored pattern 100 μA 7 μA
RTC timer + memory 10 μA 10 μA
RTC timer only 5 μA 5 μA
Power off 0.1 μA 0.1 μA
RF working TX, 802.11b/g/n @ 19.5 dBm 190~240 mA 135~190 mA avg, 200~310 mA peak
TX, 802.11n @ 13 dBm 180 mA 120 mA avg, 160 mA peak
RX, 802.11b/g/n 95~100 mA 68 mA

Radio capabilities

ESP32-S2 promises an improved and more stable WiFi connection compared to ESP32. The new Time of Flight feature gives the possibility to calculate the distance between devices. On the downside, ESP32-S2 comes without bluetooth support, reducing the types of application this can be used for.

ESP32 vs ESP32-S2 radio capabilities
ESP32 ESP32-S2
WiFi 802.11b/g/n 802.11b/g/n
Data rate up to 150 Mbps up to 150 Mbps
ESP-MESH Supported Supported
Fine Time Measurement / Time of Flight N/A Supported
Bluetooth v4.2 + BLE N/A

Peripherals and sensors

The most important difference between the two chips is the addition of the USB, LCD and Camera interfaces for the ESP32-S2. These new interfaces will allow makers to video streaming applications or user interactive devices. Also, S2 supports more cryptographic accelerators, making it suitable for secure applications.

ESP32 vs ESP32-S2 peripherals and sensors
Feature ESP32 ESP32-S2
GPIO 34 43
ADC 2 x 12-bit, 18 channels 2 x 12-bit, 20 channels
Hall sensor Yes No
DAC 8-bit, 2 channels 8-bit, 2 channels
Temperature sensor No Yes (-20ºC to 110ºC)
Touch sensor 10 14
Ultra-Low-Power Co-processor Yes Yes
LCD interface No 8-bit serial RGB
Camera interface No 8/16-bit DVP
USB No USB 1.1 OTG
Ethernet MAC interface Yes No
SDIO/SPI controller Yes Yes
UART 3 2
I²C 2 2
I²S 2 1
Infrared controller 8 channels 4 channels
Pulse counter 8 channels 4 channels
LED PWM 16 channels 8 channels
SPI 3 4
Accelerator AES,SHA,RSA,ECC AES, ECB/CBC/OFB/CFB/CTR, GCM, RSA, ECC

ESP32 vs ESP32-S2 conclusions

With ESP32-S2, Espressif is focusing on the smart home devices market by providing improved RF and security, as well as more human-interaction peripherals. The lack of bluetooth, however, might limit the applications range of this chip, especially for amateur makers.

Do you need to upgrade your ESP32 with ESP32-S3? Well, unless you are planning to use the new peripherals, like the LCD or the Camera interface, then the ESP32-S2 won’t give you many other advantages. The price for ESP32-S2 will probably be higher than the old ESP32.

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