In the early 2000s, Arduino revoluzionized the hobbyist market for microprocessors: due to their simple-to-use programming environment Arduino IDE and their relatively cheap development boards, millions of Makers and DIY enthusiasts started to add microprocessors to their DIY projects.
[!NOTE] Arduino is the name of a company that originally developed the breakout boards that carried the microprocessor and were simple to use. Arduinos are the (many different) models of breakout boards that the company released. One of the early boards was called Arduino Uno.
Why Arduino Got Challenged By ESP32
The amazing Arduino success story did not last forever. Today, many users have switched to ESP32 or are thinking about it. Before we look at the differences, here is why Arduino jeopardized its initially predominant market position:
- Missing Uniqueness: Arduino never produced its own microprocessors. They are a company developing and producing breakout boards that simplified using microcontrollers. That’s why they soon faced huge competition from other board manufacturers, especially since their designs were open source. They could do the same, just cheaper. In a first step, the market was flooded with cheap Arduino Clones: much cheaper copies that performed equally well.
- Missing Vision: Initial success made the company focus on their original concept: while Arduino models became smaller and more capable, they long focused on the initial ATMega family of microcontrollers. When Espressif released its new microcontroller ESP8266, many board manufacturers acted fast and adapted the Arduino programming framework to this much faster and more capable microcontroller that also came with WiFi connectivity built-in. Arduino only recently left the ATMega path and started to produce its own ESP32-based boards (Nano ESP32). In essence, the concept of competition worked well and led to much more powerful microcontrollers in much smaller form factors that were much cheaper.
- Internal Conflicts: As if all of this wasn’t enough, with raising success and ever more money involved, the company Arduino got preoccupied with internal legal battles over contracts and ownerships.
Where To Get
Here is where you can get microcontroller breakout boards:
- Arduinos: The original Arduinos are produced by the italian company Arduino. There are numerous nameless board manufacturers who produce clones based on the same or slightly modified open-source designs.
- ESP32: Since ESP32 is the name of a microcontroller family and not a specific breakout board, all microcontroller boards with an ESP32 are “originals”: they all use the same genuine microcontroller. The microcontroller producer Espressif sells its own Dev Kit boards through resellers, and there are countless board manufacturers who also produce breakout boards with this microcontroller: Espressif has open sourced its schematics and PCBs. If you are interested in highest production quality and willing to spend more, look for renown board manufacturers such as Adafruit, Sparkfun, Seeed, NodeMCU, or get the Dev Kit directly from the microcontroller manufacturer Espressif through one of its resellers.
In this article, for simplicity I am referring to ESP32 when in reality I mean the specific ESP32 WROOM microcontroller. Espressif has an entire family of ESP32 microcontrollers, including the S2, S3, C3, and C6. I’ll look at the differences in a separate article.
Shopping Sources
You can get breakout boards - both from original manufacturers like Arduino and clones - at a variety of sources. Price differences for the very same board often are huge:
- Reseller: Official resellers such as Digikey or Mouser are a trusted source to get a board from an original manufacturer. They are pricey though, especially shipping cost is high.
- Amazon: Amazon offers both original boards and clones (produced by nameless board manufacturers). Shopping here is convenient but often still pricey.
- AliExpress: Market places like AliExpress let you buy directly from Chinese sources, bypassing other players. Delivery takes 1-2 weeks. Prices are extremely competitive as you practically buy from the manufacturer. Many of the AliExpress offers are essentially the same products you find at Amazon, too.
Often, boards are offered as discounted bulk packs of 3 or 5. It makes sense to buy more than one board, just in case you damage one or find it so useful that you’d like to use it in additional projects, too.
The Rise Of ESP Microcontrollers
When the Chinese company Espressif in 2015 released their ESP8266 microprocessor, it became an instant success.
Many third parties started to release cheap and very small breakout boards that could technically do what Arduinos can do, just better and faster and cheaper. These new family of ESP microprocessors were code-compatible to Arduinos and could be programmed using the same tools.
Meanwhile, Espressif has released numerous improved microprocessors in rapid succession, and the ESP32 family of microprocessors today is the de-facto standard for very fast one- and dual core microcontrollers. They all come with wireless (WiFi) support, and the latest microcontrollers also support Bluetooth, Zigbee, and Threads.
The company Arduino produces breakout boards only and uses third-party microcontroller. The ESP32 is no company but one specific microcontroller model produced by the company Espressif. While Arduinos were soon cloned and produced by third party for much cheaper prices, ESP32 breakout boards are always produced by third party, and the ESP32 producer Espressif focuses on its microcontrollers.
The picture below shows the original ESP32 development board on the right that was considerably bigger than the original ESP8266 in the middle. Meanwhile, ESP32 dev boards are available in any size, including miniature sizes like the board on the left (produced by the manufacturer Seeed):
Moving From Arduino To ESP32
Whether you are already using Arduinos and are thinking about a move to ESP32, or whether you are completely new and try to find the right microcontroller board to start with, here is a drill down on differences:
Comparing Arduino UNO And ESP32
The Arduino Uno is not the fastest and most capable Arduino but among the most common and popular ones.
The ESP32 DevC board (available from many sources in many flavors) using the ESP32 WROOM microcontroller is not the fastest and most capable ESP32 microcontroller-based board either, but just like the Arduino Uno it is the most common and cheap one you can get.
This is why these two are compared here.
Both can be programmed in the same way using the same tools (i.e. Arduino IDE, or VSCode and platformio).
| Item | Arduino Uno | ESP32 Devkit C | Comment |
|---|---|---|---|
| Price | EUR 25-30 | EUR 3-7 | depending on source |
| Microcontroller | 16 MHz ATmega328P | 240 MHz ESP32 WROOM | |
| Board Supply Voltage | USB or 5V | USB or 5V or 3.3V | directly supplying 3.3V bypasses the voltage regulator |
| internal Voltage | 5V | 3.3V | |
| GPIO Pins | 14 | 26 (22 PWM 16bit) | |
| Analog In Pins | 6 (10bit, 0-1024) | 16 (12bit, 0-4096) | |
| Digital-to-Analog (DAC) | 1 | 2 | |
| UART | 1 | 3 | Serial Interface, i.e. USB |
| SPI | 1 | multiple (software defined) | to connect fast peripherals |
| I2C | 1 | multiple (software defined) | to connect slow peripherals |
| Calc Primes in 30sec | 3.000 | 125.000 | performance test |
| Pins | 30 | 38 | physical pins |
| WiFi | no | yes | access point, station, and both |
| Bluetooth | no | yes | BLE and Classic |
| ESP-NOW | no | yes | WiFi-protocol to directly connect two microcontrollers |
| Arduino IDE | yes | yes | ESP32: install ESP32 Board Package (esp32 dev) |
| VSCode/platformio | yes | yes | comes with support for virtually any mcu |
| Code Compatible | yes | yes | include |
Voltage Differences
The most important difference between Arduinos and ESP32 is their operating voltage: Arduinos use 5V whereas ESP32 uses 3.3V.
You can still power all boards by either connecting it to USB, or by supplying 5V or 3.3V to the appropriate pin. All boards come with voltage regulators. This is why ESP32 should best be powered by supplying 5V. Do not supply 3.3V directly as this bypasses the internal power regulator, and when your power supply isn’t supplying exactly 3.3V, you may be destroying the microcontroller.
This difference is important when communicating with peripheral devices such as sensors etc.:
Translating Voltage
Some peripherals accept a wide input voltage from 3.3V-5V so you can run them equally well with Arduinos and ESP32. Simply supply the same voltage the microcontroller uses.
Occasionally, the peripheral voltage does not match the microcontroller voltage. This can happen both ways:
Arduinos (5V) can run 3.3V peripherals by supplying the 3.3V to the peripheral from its 3.3V pin. ESP32 (3.3V) can run 5V peripherals by supplying the 5V to the peripheral from its 5V pin.
The latter requires that you supply 5V to the ESP32. It will then use its internal voltage regulator to create the required 3.3V for the microcontroller, and still supply the 5V to peripherals when they need them. If you power the ESP32 directly with 3.3V through its 3.3V pin, then the board will not supply 5V at the 5V pin, and you cannot run 5V peripherals off the board: the ESP32 comes with a voltage regulator that can turn 5V to 3.3V, but not 3.3V to 5V.
Level Shifter
Whenever you use a different voltage for peripherals, you need to translate their output voltage back to the voltage the microcontroller needs.
For example, when you run a 3.3V SD Card Reader on a 5V Arduino, the SD Card Reader sends data back to the microcontroller GPIO pin using 3.3V. This voltage needs to be shifted to 5V.
Likewise, when you run a 5V Sensor on a 3.3V ESP32, the sensor sends back 5V data to the ESP32 GPIO pin, and you need to shift the voltage level down to 3.3V.
Fortunately, this is neither complex nor expensive: level shifter boards can be hooked between peripheral and microcontroller board to do the level shifting for you.
Often, you can get away without a level shifter when receiving signals from peripherals: Espressif officials once mentioned in a press release that ESP32 GPIO pins are 5V tolerant even though this assurance is not found in the data sheet. When you send information to a peripheral, check its data sheet to see whether it is tolerant enough, and whether it interprets the actual voltage you send as a high signal. If in doubt, use a level shifter anyway.
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(content created Mar 29, 2024)