RP2040: A Powerful, Low-Cost Microcontroller for Custom Electronics

At EZMation.com, we use several different microcontroller families for custom electronics. For a simple sensor or relay controller, an inexpensive 8-bit AVR is often all we need. For a connected product, an ESP32 may be the better choice. But there is another option worth considering when a project needs more processing power, USB connectivity, or precise control of hardware without the added cost of wireless networking.

That option is the RP2040 from Raspberry Pi.

The RP2040 is the processor used in the original Raspberry Pi Pico. It has two 32-bit processor cores, a flexible programmable I/O system, built-in USB hardware, and enough memory for many fairly sophisticated embedded applications. It is also inexpensive enough to make sense in custom products, not just development boards.

The interesting part is not just what the RP2040 can do. It is how much external hardware you need to build around it, and how that compares with the other microcontrollers we use.

RP2040 Specifications at a Glance

Pricing is an approximate planning range for the bare IC, not a guaranteed current distributor quote. Package, quantity, supplier and availability affect the actual price. The RP2040 also requires external flash, a clock source and supporting circuitry in a custom design.

How Does the RP2040 Compare With Our Other Microcontrollers?

Our existing guide, Choosing the Right Microcontroller for a Custom Electronics Project, covers six processors we regularly consider for custom designs: the ATtiny816, ATmega328PB, ESP8266, ESP32-C3, ESP32-S3 and ESP32-C6.

The RP2040 belongs in that conversation, but it fills a somewhat different role.

These specifications are not a direct measure of application performance. Processor architecture, firmware, memory access and the work being performed all matter. A 240 MHz processor is not automatically the best choice for every task.

The RP2040's two cores and relatively generous RAM make it a major step up from the small AVR parts for many applications. Its eight programmable I/O state machines are another important advantage. They can handle specialized digital signaling independently of the main application code.

However, the RP2040 has no built-in Wi-Fi or Bluetooth. If a product needs a wireless connection, an ESP32-C3 or ESP32-C6 may be a better starting point.

The RP2040's Biggest Hardware Advantage: Programmable I/O

One of the most interesting features of the RP2040 is its Programmable I/O, usually called PIO.

Most microcontrollers have fixed hardware peripherals for interfaces such as UART, SPI and I2C. Those peripherals are useful, but sometimes a project needs a timing pattern or communication protocol that does not fit the available hardware.

The RP2040 lets us implement custom digital interfaces using small PIO programs. These programs run on dedicated state machines rather than requiring the main CPU to handle every transition.

That can be useful for applications such as:

• Driving addressable LED strips with precise timing.
• Generating custom serial protocols.
• Reading unusual digital sensor interfaces.
• Producing carefully timed pulse sequences.
• Emulating certain digital interfaces.
• Handling data streams while the main processor runs the application.

For example, suppose we are building a custom LED controller that needs to drive several outputs while also communicating with a computer over USB. On a smaller microcontroller, the timing requirements might consume a large portion of the available processing time. With the RP2040, PIO can handle the LED signaling while the processor manages USB communication, commands and configuration.

This is not the same as having an unlimited number of hardware peripherals. PIO has its own resource limits, and the program still needs to be designed correctly. But it provides a lot of flexibility for the price.

How Much Does an RP2040 Design Actually Cost?

The price of the processor is only one part of the bill of materials.

A bare RP2040 chip may cost roughly $0.70-$1.50 in low quantities, depending on the supplier and package. That sounds inexpensive, but it does not tell the whole story.

A custom RP2040 circuit generally needs:

• The RP2040 processor.
• External QSPI flash for program storage.
• A 12 MHz crystal and associated components for the reference clock.
• A 3.3 V power supply and the required power-management circuitry.
• Decoupling capacitors and other supporting components.
• A USB connector if USB is required.
• Optional programming and debugging connections.

The exact component count depends on the schematic, power source, USB implementation and design requirements. Some designs also need additional connectors, protection components, regulators or interface circuitry.

For comparison, an ESP32-C3 module often includes the processor, flash, crystal and radio-related circuitry in one component. That module may cost more than the bare RP2040, but it can reduce the number of components that need to be placed on the PCB.

An ATtiny816 or ATmega328PB can also be cheaper and simpler for a basic control circuit, particularly when the application does not need much memory or processing power.

The important comparison is the cost of the complete board, not the price of the processor by itself.

RP2040 vs. ESP32: Which One Needs Fewer Components?

This is where the application makes a real difference.

RP2040

A custom RP2040 design needs external flash and clock circuitry. It also needs its power supplies and supporting capacitors. If USB is required, the USB connector and appropriate protection or filtering may be added.

The RP2040 includes the USB controller and PHY, so a separate USB-to-serial converter is not inherently required for USB communication. The chip can support USB device and host applications, subject to the power, connector and software requirements of the design.

ESP32-C3

An ESP32-C3 module typically integrates the processor, flash, crystal and RF components. It also includes Wi-Fi and Bluetooth LE.

That means we can often add the module, a suitable 3.3 V power supply, decoupling capacitors and the required connectors without designing a separate RF section.

For a wireless product, this is a substantial advantage. The ESP32-C3 can eliminate the need for an additional wireless module entirely.

ESP32-S3

The ESP32-S3 module follows a similar approach but provides more processing capability and features suited to USB devices, displays, audio and other demanding applications.

Depending on the module and application, extra PSRAM may be available or required. The S3 can still be a simpler overall design than an RP2040 plus a separate wireless module when the product needs both USB and wireless connectivity.

ATtiny816 and ATmega328PB

The AVR parts can be particularly simple for products with limited requirements. They do not need external program flash, and their built-in peripherals cover many common control tasks.

A basic AVR board can have a very small component count. If the application only reads a few sensors and controls some outputs, the extra processing power of the RP2040 may not justify the added hardware.

Can the RP2040 Be Used Without a Development Board?

Yes. The Raspberry Pi Pico is an excellent way to prototype an application, but a production design does not have to use the entire board.

The RP2040 is available as a bare IC, allowing us to design a custom PCB around the processor. We can place the connectors, sensors, power circuitry and other components exactly where the product needs them.

This is useful when the Pico board is larger than the finished product allows, when a custom connector is needed, or when the product requires a specialized mix of inputs and outputs.

There is one important consideration: the bare RP2040 is not a drop-in replacement for a Pico module. We need to design and validate the flash, clock, power, USB and programming circuitry. Raspberry Pi publishes hardware design documentation and reference designs that help with this process.

For a one-off prototype, a Pico board is usually the easiest way to get started. For a product that will be manufactured in quantity, a custom RP2040 design may be worth the effort.

What About Power Consumption?

The RP2040 is a capable general-purpose microcontroller, but it is not automatically the best choice for a battery-powered device.

The ATtiny816 is a better fit for many applications that spend nearly all their time sleeping and only need to wake up to read a sensor or change an output. Its simpler architecture and low-power capabilities can make a big difference in a small battery-powered product.

The RP2040 has sleep and dormant modes, but the complete board design matters. External flash, regulators, connected peripherals and the way the firmware manages power can all affect the final current consumption.

An RP2040 may be a good choice for a battery-powered product that needs more processing power, USB, or specialized digital signaling. For a tiny wireless sensor, an ESP32-C3 or ESP32-C6 may be more appropriate, especially if the device needs to connect to a network.

We would measure the current consumption of the actual circuit rather than choosing based on processor specifications alone.

Programming the RP2040

The RP2040 has a good software ecosystem, which is one reason it is attractive for custom electronics.

Two common choices are:

C/C++: The Raspberry Pi Pico SDK provides access to the processor, peripherals, USB and PIO. It is a good fit for products where timing, memory usage and hardware control are important.

MicroPython: MicroPython makes it easy to experiment with sensors, displays, serial interfaces and other peripherals. It is particularly convenient for prototypes and applications where development speed matters more than squeezing out every last bit of performance.

The RP2040 also supports a simple USB bootloader workflow. On a typical Pico board, firmware can be loaded by holding the BOOTSEL button while connecting USB and copying the firmware file to the device. A custom board needs an appropriate way to access the bootloader, usually through a BOOTSEL arrangement and USB connection.

For production hardware, we also need to plan for manufacturing programming, debugging, firmware updates and recovery from failed updates. Those details are worth considering before the PCB layout is finalized.

What Would We Use the RP2040 For?

At EZMation, we would consider the RP2040 for applications that need more capability than a small AVR but do not require built-in wireless connectivity.

These are starting points, not hard rules. For example, an ESP32-S3 may be a better fit than the RP2040 if a product needs USB, Wi-Fi and Bluetooth in the same design. Conversely, if the product needs custom digital signaling and does not need a radio, the RP2040 deserves a close look.

So, Is the RP2040 the Right Choice?

The RP2040 fills a useful gap between small, inexpensive microcontrollers and more complex wireless processors.

We would look closely at it when a project needs:

• More RAM and processing capability than an ATtiny816 or ATmega328PB.
• USB device or host functionality.
• Precise digital timing or custom communication protocols.
• Multiple interfaces running at the same time.
• A flexible development environment with C/C++ and MicroPython support.

We would probably choose an ESP32-C3 or ESP32-C6 instead when Wi-Fi or Bluetooth is a requirement. We would stick with an ATtiny816 or ATmega328PB when the application is simple enough that the extra processing power is unnecessary.

The RP2040 is not always the cheapest solution, and it is not always the fastest. Its real advantage is the combination of two processor cores, flexible I/O, USB support and a reasonable chip price.

As with any custom electronics project, the right choice comes down to the complete design. The processor, external components, PCB area, firmware development and production requirements all affect the final cost.

Need Help With a Custom Electronics Project?

At EZMation.com, we design custom electronics for home automation, commercial applications, special projects and products that do not fit into an off-the-shelf solution.

We can help select the right microcontroller, design the schematic and PCB, develop the firmware, and build the enclosure or mechanical components. Whether an RP2040, AVR or ESP32 is the best fit, we start with what the product needs to do.

Have an idea for a custom electronic device? Contact EZMation.com and let's work out the best approach.

Specifications and prices are approximate and may change with component availability, supplier and order quantity. Bare-IC pricing should not be compared directly with module pricing. Review the manufacturer's current datasheet and hardware design guidance before committing a design to production.