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# ESP32 DevKit V1 vs ESP8266 NodeMCU

The ESP32 does everything the ESP8266 does and more: two Xtensa LX6 cores at up to 240 MHz, 520 KB of SRAM, Wi-Fi plus Bluetooth v4.2 Classic and LE, and 15 ADC pins on the DevKit V1 (ESP32 datasheet v5.3, pp. 3, 4), against one 80 MHz (160 MHz maximum) core, Wi-Fi only and a single 10-bit analog input on the NodeMCU (ESP8266EX datasheet v7.1, pp. 2, 7, 17). Both are 3.3 V boards powered from 5 V USB, so choose the ESP8266 only to reuse existing ESP8266 code or for the simplest Wi-Fi switch or sensor.

## Side by side

|  | ESP32 DevKit V1 | ESP8266 NodeMCU | Source |
| --- | --- | --- | --- |
| CPU | Dual-core Xtensa LX6, up to 240 MHz | Single-core Tensilica L106, 80 MHz (160 MHz maximum) | Espressif ESP32-WROOM-32 datasheet v3.8, pp. 2, 3; Espressif ESP8266EX datasheet v7.1, pp. 2, 7 |
| RAM | 520 KB SRAM on chip | Under 50 KB free for user code with Wi-Fi connected | Espressif ESP32 datasheet v5.3, p. 4; ESP8266EX datasheet v7.1, p. 8 |
| Flash on the board | 4 MB (ESP32-WROOM-32) | 4 MB (ESP-12E) | ESP32-WROOM-32 datasheet v3.8, p. 2; NodeMCU DevKit v1.0 open-hardware design |
| Wireless | Wi-Fi 802.11 b/g/n, Bluetooth v4.2 BR/EDR and LE | Wi-Fi 802.11 b/g/n only, no Bluetooth | Espressif ESP32 datasheet v5.3, p. 3; ESP8266EX datasheet v7.1, p. 2 |
| Analog inputs | 15 ADC pins on the 30-pin board (6 on ADC1, 9 on ADC2), 12-bit | 1 (A0), 10-bit, about 0 to 3.2 V through the board's divider | ESP32 DevKit V1 pinout; ESP32 datasheet v5.3, p. 4; ESP8266EX datasheet v7.1, p. 17; NodeMCU DevKit v1.0 schematic |
| DAC | Two 8-bit channels (GPIO25, GPIO26) | None | Espressif ESP32 datasheet v5.3, p. 4; ESP8266EX datasheet v7.1 |
| Usable GPIO on the board | 25 | 11 | ESP32 DevKit V1 30-pin pinout; NodeMCU DevKit v1.0 pinout |
| Logic level | 3.3 V, inputs to VDD + 0.3 V | 3.3 V, inputs to 3.6 V, 12 mA per pin | ESP32-WROOM-32 datasheet v3.8, p. 26; ESP8266EX datasheet v7.1, p. 19 |
| Default I2C pins (Arduino core) | GPIO21 (SDA), GPIO22 (SCL) | D2 / GPIO4 (SDA), D1 / GPIO5 (SCL) | arduino-esp32 and ESP8266 Arduino core pin definitions |

## Which one to pick

### Pick the ESP32 DevKit V1 when

- Any new connected project: two cores, 520 KB of SRAM and Bluetooth beside Wi-Fi (ESP32 datasheet v5.3, pp. 3, 4).
- Several analog sensors, since the DevKit V1 breaks out 15 ADC pins; keep them on ADC1 (GPIO32 to GPIO39) while Wi-Fi is on.
- Bluetooth to a phone or a classic serial link through BluetoothSerial, which needs the original ESP32's Bluetooth Classic.

### Pick the ESP8266 NodeMCU when

- Existing ESP8266 projects and firmware such as Tasmota or ESPHome configurations already written for it.
- A simple Wi-Fi relay, switch or single sensor where one analog input and 11 GPIO are enough.
- Projects built around ESP8266 libraries that have no ESP32 port.

## Swapping one for the other

- Both are 3.3 V boards, not 5 V tolerant (ESP32-WROOM-32 datasheet v3.8, p. 26; ESP8266EX datasheet v7.1, p. 19), and both take 5 V on VIN or USB, so level shifting stays as it was.
- Install the esp32 board package by Espressif and select DOIT ESP32 DEVKIT V1 instead of NodeMCU 1.0 (ESP-12E Module).
- Change the Wi-Fi headers: ESP8266WiFi.h becomes WiFi.h, ESP8266WebServer.h becomes WebServer.h and ESP8266mDNS.h becomes ESPmDNS.h.
- Pin names change: the NodeMCU's D1, D2 labels do not exist on the ESP32, so use GPIO numbers. Move I2C from GPIO4/GPIO5 to GPIO21 (SDA) and GPIO22 (SCL), or pass the pins to Wire.begin(sda, scl).
- analogRead() returns 0 to 4095 on the ESP32's 12-bit ADC instead of 0 to 1023 on A0, and has no board divider in front of it, so rescale any conversion.

## Questions

### Is the ESP32 a replacement for the ESP8266?

For new designs, yes: it has two cores at up to 240 MHz, 520 KB of SRAM and Bluetooth v4.2 beside the same 2.4 GHz Wi-Fi (ESP32 datasheet v5.3, pp. 3, 4). Code needs a few changes, mainly the Wi-Fi headers and the pin numbers.

### Does the ESP8266 have Bluetooth?

No. The ESP8266EX has 2.4 GHz Wi-Fi only (ESP8266EX datasheet v7.1, p. 2). The ESP32 adds Bluetooth v4.2 Classic and LE (ESP32 datasheet v5.3, p. 3).

### How many analog inputs does each board have?

The NodeMCU has one, A0, a 10-bit input that reads about 0 to 3.2 V through the board's 220 kΩ / 100 kΩ divider (ESP8266EX datasheet v7.1, p. 17; NodeMCU DevKit v1.0 schematic). The 30-pin ESP32 DevKit V1 breaks out 15 ADC pins, six of them on ADC1, which stays usable with Wi-Fi on.

### Are both boards 5 V tolerant?

No. The ESP32's inputs are limited to VDD + 0.3 V (ESP32-WROOM-32 datasheet v3.8, p. 26) and the ESP8266's to 3.6 V (ESP8266EX datasheet v7.1, p. 19). Use a level shifter or divider on 5 V signals with either.

### Will my ESP8266 sketch compile for the ESP32?

Not unchanged. Swap ESP8266WiFi.h for WiFi.h and ESP8266WebServer.h for WebServer.h, replace D-pin labels with GPIO numbers, and rescale analogRead() from 0 to 1023 to 0 to 4095. Most libraries for sensors and displays support both.

## References

- [ESP32 DevKit V1](https://www.tinkered.ai/components/esp32-devkit-v1.md)
- [ESP8266 NodeMCU](https://www.tinkered.ai/components/esp8266-nodemcu.md)
- Espressif ESP32 datasheet v5.3
- Espressif ESP32-WROOM-32 datasheet v3.8
- Espressif ESP8266EX datasheet v7.1
- NodeMCU DevKit v1.0 schematic

## Try it

Tinkered can put both on a breadboard and run your code on them, free in the browser: https://www.tinkered.ai/compare/esp32-devkit-v1-vs-esp8266-nodemcu