Which ESP32 is Best for Your Project? [YouTube]

Published on January 18, 2024

Selecting an ESP32 wireless microcontroller used to be an easy thing to do since there was only one model available.

But, that has all changed in the last few years with the release of multiple new models.

These new models give you more design flexibility, but they make the selection process much more challenging, and in fact quite overwhelming for many.

So, in this video you’re going to learn about the different ESP32 models and how to pick the best one for your project.

There are three stages of ESP32 solutions you need to be aware of:

1) SoC – System on a Chip – This is the bare ESP32 chip you’d purchase if you are doing a fully custom design.

2) Modules – An ESP32 module is designed to be soldered onto a custom PCB so it eliminates the need to custom design the ESP32 circuit and antenna.

Modules are also pre-certified so they simplify your certification process compared to using an SoC in a custom circuit, especially those with a built-in antenna.

3) Development kits – These are larger boards that include the embedded module but they bring out the various I/O to header pins for easy access during early development.

When selecting the ESP32 for your project you want to start at the most fundamental level with the SoC and then work your way up to the module and then the development kit.

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Be sure you download my free guide “From ESP32 Prototype to Production” using the link in the description below.
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Selecting the SoC:

Designing with the SoC is usually only done after you reach a few hundred thousand production units. For lower production volumes it’s almost always best to start by using a pre-certified module.

A custom SoC design only makes sense at higher production volumes when the increase in profit margin outweighs the extra cost of certification that’s required with a custom wireless design.

Although most projects are better off using a module, we’re going to start by selecting the ESP32 SoC.

The Espressif ESP WiFi family of microcontrollers started with the original ESP8266 which embedded a single-core microcontroller with a WiFi radio.

Then in 2016, Espressif released the first ESP32 which added a Bluetooth radio and an optional dual-core microcontroller.

Even though the ESP32 included lots of new capabilities compared to the ESP8266, the price increase was minimal.

The original model of the ESP32 is still available, but for various reasons it’s not the version I recommend for most projects.

For years, you only had to decide on a single or dual-core version, the amount of memory needed, and the package.

But, then lots of new models in the ESP32 family came along with many significant differences.

The additional options are great to have, but they also drastically complicate the selection process.

They’ve now added the ESP32-S, ESP32-C, and ESP32-H chip families.

ESP-S:

The S series is intended to be a better replacement for the original ESP32, whereas the C and H series are more specialized models.

The ESP32-S series is based on a new and improved version of the 32-bit processor core called the LX7 whereas the original ESP32 model used the LX6 version of the core.

The S series has a lot of other improvements compared to the original ESP32 including improved security features.

One of the most desirable features that’s always been missing from the original ESP32 is USB.

The original ESP32 didn’t have a native USB port, so it required the use of a separate USB-to-UART converter circuit with a speed limited to only 3 megabits/sec.

But, that’s been fixed with the S series which adds full-speed USB On-The-Go which theoretically can do up to 12 megabits/sec.

The On-the-Go just means it can switch between the roles of host and device.

Other improvements in the S series include more GPIO pins, better low-power capabilities, and the ability to add up to 1GB of external RAM or Flash memory.

So the S series is faster and more secure, and it includes USB support, more GPIO pins, and it has the ability to add more memory than the original ESP32.

There are currently two versions in the S series: S2 and S3

The S2 is a single core and only supports WiFi, not Bluetooth

On the other hand, the S3 is a dual-core microcontroller that supports both WiFi and Bluetooth 5, and it comes with more embedded Flash memory.

ESP-C:

The C series is fundamentally different from the ESP32’s we’ve discussed so far.

Its design arose out of two things: pandemic supply chain issues and the popularity of small, low cost IoT products like smart plugs.

Although the ESP32 S series is impressive and intended to be a replacement for the original series, one negative is it comes in a larger package.

The feature that most significantly increases the chip size is the amount of embedded Flash memory.

Both models of the S series come in packages measuring 7mm x 7mm, whereas the C series is available in packages as small as 4 mm x 4mm or 5mm x 5mm.

So Espressif decided to design a new ESP32 model that would require less memory and be smaller and cheaper.

Apparently this was the motivation for the creation of the C series.

The biggest change they made to accomplish these new design priorities was using a totally different processor core.

The C series uses a RISC processor instead of the processor core used in all of the previous models.

The C series comes in three versions including the C2, C3, and C6.

The C2 has a single RISC core operating at up to only 120MHz. It supports both WiFi and Bluetooth 5 but it doesn’t include USB, and the security features included are minimal.

The C2 doesn’t appear to be stocked by any of the big component distributors, so I would avoid using it in most cases.

The C3 on the other hand operates at up to 160MHz, includes a full-speed USB port (although without OTG like the S series), and has much better security features. It too supports WiFi and Bluetooth 5.

The C6 version uses the same 160MHz core as the C3, but it adds an additional low-power RISC core that runs at only 20MHz.

The C6 also steps it up by supporting WiFi 6 whereas all of the previous versions we’ve looked at including the S series, only support WiFi 4.

In addition to WiFi 6 and Bluetooth 5, the C6 also adds wireless support for Zigbee and Thread protocols.

Overall, the C series primarily makes sense if you need the smallest possible chip size at the lowest cost, or perhaps if you need the ZigBee or Thread support that comes with the C6.

ESP32-H:

Next we have the ESP32 H series which currently consists only of the H2 version.

The H2 is an extension of the C series and uses the same RISC processor core, except it’s only running at 96MHz compared to the 120-160MHz speeds of the C series.

The biggest difference between it and every other Espressif chip is it doesn’t include WiF. Instead, it only supports Bluetooth, Zigbee, Matter, and Thread.

Due to these protocols’ lower throughput speeds compared to WiFi, the ESP32-H2 can run at a lower clock speed and consume less power.

Selecting the module:
Once you’ve selected the SoC for your project, you want to choose the best module that uses this SoC.

Fortunately, this part is pretty easy once you’ve selected the chip itself.

Now, the main decision you need to make is whether you want a module with a built-in PCB antenna, or one with a connector for an external antenna.

If the internal antenna’s performance meets your requirements then I’d select a module with a built-in antenna which simplifies your design and the certifications process.

Selecting the development board:

Once you’ve selected the module, you simply have to select the development board that uses that module.

The development board is a larger PCB that connects all of the various I/O to header pins for easy access.

The development board also includes the USB-to-UART converter for easy programming, and a linear regulator to step down the 5V USB supply voltage to the 3.3V required by the ESP32.

This UART-to-USB converter is also included on the development boards for the models that include a native USB port, like the S series, C3, C6, and H2 models.

For those boards you’ll find two USB connectors.

One goes through the USB-to-UART converter circuit and is limited to only 3Mb/s, and the other connects to the native USB port and can do up to 12 Mb/s.

Either USB port can be used for programming.

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For most projects you’ll likely want to go with the S2 or S3 models. Choose the S2 if you only need WiFi. If you also need Bluetooth or an additional processor core, choose the S3.

For the S series I’d suggest the MINI module versions which come in both S2 and S3 flavors with either a built-in antenna or a connector for an external antenna.

Which ESP32 is Best for Your Project? [YouTube]

Which ESP32 is Best for Your Project? [YouTube]

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