9 ESP32 Design Mistakes That Kill Your Product
The ESP32 looks like the perfect chip.
You get Wi-Fi, Bluetooth, dual-core processing, plenty of memory and peripherals… and it’s dirt cheap.
It’s also everywhere from DIY maker projects to full-scale commercial products. It’s one of the most popular chips in the world for connected devices.
So it’s easy to assume that popularity and features like these will make development easier.
But that’s exactly where so many developers go wrong.
Because while the ESP32 can simplify certain things, it also introduces hidden design pitfalls that can quietly kill your product especially if you don’t know what to watch for.
In this article, we’re going to break down 9 of the most common ESP32 design mistakes that can sabotage your product and show you how to avoid every one of them.
Mistake 1: Choosing the Wrong ESP32 Variant
Espressif has released a whole zoo of ESP32 variants. You’ve got the ESP32, S2, S3, C3, C6, H2, and the new P4. Each one has different CPU cores, wireless support, power characteristics, memory sizes, and available peripherals.
Choosing the wrong one can lead to wasted power, missing features, sourcing problems, or even a complete board redesign.
Some developers default to the most powerful option, thinking more is better.
But in reality, that mindset just unnecessarily drives up your product’s cost, and ends up wasting power and generating unnecessary heat.
Others go for the cheapest option, only to discover too late that it doesn’t support Bluetooth, lacks enough GPIOs, or can’t support their peripherals.
A better approach is to start by mapping out your product’s actual needs. Do you need Wi-Fi, Bluetooth, or both? How many pins? How much RAM and flash? What’s your power budget? What peripherals do you require?
Then choose the variant that meets those needs with some room to grow but without going overboard. And always check the lifecycle status and forecast availability.
The P4 variant, for example, offers a major leap in performance and peripherals.
But availability is limited. It’s exciting technology, but unless you’re building in large volume with a locked-in supply chain, it may introduce more risk than reward.
Mistake 2: Not Optimizing Power Consumption
The ESP32 is capable of ultra-low power operation, but most designs don’t take advantage of it.
I’ve seen products that should have lasted weeks on a single battery charge die in just a few days. All because the developer didn’t turn off unused features or implement a proper sleep strategy.
One common issue is leaving Wi-Fi or Bluetooth enabled when the product isn’t communicating. That alone can drain a battery fast.
Another is failing to use deep sleep between tasks. And sometimes, sensor readouts are running full-time when they only need to sample every few seconds or minutes.
Power optimization has to start early. That means defining your expected duty cycle, selecting low-power components, and writing firmware that puts the ESP32 into deep sleep whenever possible.
You also need to think about wake-up sources, latency, and how to manage communication in bursts rather than keeping everything on all the time.
If you’re using a dual-core variant, it may be possible in some environments like ESP-IDF to idle or even disable the second core to save power.
For simpler products, a single-core chip like the ESP32-C3 or C6 might be a better fit. Fewer cores mean lower idle power, simpler task scheduling, and less heat.
Always measure your current draw during both sleep and active modes. If you’re seeing milliamps in deep sleep, something’s wrong.
Get this right and the ESP32 can get by with a trickle of power. Get it wrong and your customers will be forced to recharge much more often than necessary.
Mistake 3: Using Bare Chips Instead of Certified Modules
The bare ESP32 chip looks cheaper than a pre-certified module.
And you might be thinking, I’m already custom designing the PCB, so why not just use the bare chip and maximize profit?
But if you go that route, you’re now responsible for the full RF layout, impedance matching, antenna tuning, and regulatory compliance. That includes certifications like FCC, CE, and IC.
That’s no small task. You’ll need RF expertise, controlled impedance traces, specialized test equipment, and possibly multiple layout iterations.
If your board fails certification, you could face delays, redesigns, and unexpected costs.
I once worked with a startup that tried to save a couple bucks per unit by using the bare chip. They were so confident they’d sell millions of them that they wanted to maximize their profit.
They spent weeks figuring out how to do RF layout, failed certification, and ended up switching back to a certified module.
But not before they lost months and blew through much of their budget.
Unless you’re producing hundreds of thousands of units a year and have an RF expert on your team, it’s usually better to use a certified module.
You’ll still need to test emissions and overall performance, but the hardest part is already done.
That reduces risk and speeds up your timeline.
Mistake 4: Bad Antenna Placement or Design
Even if you’re using a certified ESP32 module with a built-in antenna, your PCB layout can still wreck wireless performance.
The antenna needs a clear keep-out area. No copper, no ground pour, and no nearby components. It should also be placed near the edge of the board, ideally centered along the long side. That’s where it radiates best.
If you put the module too close to a battery, a shield, or even a plastic enclosure wall, it can detune the antenna.
I once reviewed a board where the wireless module was placed right in the middle of the board and had tall metal capacitors near the antenna.
The Wi-Fi range was so bad it couldn’t hold a connection across a small room, and it was a massive redesign to fix it.
Espressif provides detailed placement guidelines in their datasheets. Follow them closely.
And always test the board inside the final enclosure, because even plastic can affect performance.
This is exactly why emissions testing and certifications are done on the complete, assembled product, not just the PCB.
Mistake 5: Ignoring Heat Dissipation
The ESP32 is small, but it can generate a lot of heat. If both cores are running, Wi-Fi is transmitting, and other peripherals are active, temperatures can climb fast, especially in sealed plastic enclosures.
I’ve seen designs work okay in the lab, but out in the field once they’re exposed to sunlight and high ambient temperatures, they start hitting thermal limits, glitching, and sometimes shutting down.
To prevent these types of problems place a copper pour under the module with thermal vias to help carry the heat away into ground, increase the board thickness, use a heat sink, or add venting to your enclosure to improve airflow.
If your product will run hot or be used outdoors, run thermal simulations or do real stress testing early. The ESP32 can handle heat, but only if your board design and enclosure help it out.
Mistake 6: Poor Power Supply Design
The ESP32 draws high peak current during Wi-Fi or Bluetooth transmissions. We’re talking hundreds of milliamps for short bursts.
If your regulator or power supply can’t keep up, you’ll get weird behavior like resets, brownouts, or dropped connections.
Everything might look fine on the bench when traffic is low. But as soon as you ramp up data transfer or wake from sleep, those power dips can cause major problems.
Make sure your regulator can handle the current with fast transient response. Just because a regulator can supply the necessary current, doesn’t mean it can always do it fast enough.
And place bulk capacitors close to the ESP32 to smooth out current spikes.
Mistake 7: Designing Without OTA Update Capability
One of the best features of the ESP32 is its built-in support for over-the-air firmware updates. But a lot of products ship without using it.
That might be fine if your firmware is flawless. But most of the time, you’ll want to fix or improve something after launch.
Without OTA, you’re stuck with manual reflashing or costly returns.
You should add OTA capability early.
Set up your flash partitions properly, test the update process with real builds, and make sure your firmware can recover gracefully if something goes wrong.
A solid OTA update process can save your product since it allows the firmware to constantly evolve.
Mistake 8: Not Testing in the Real World Early Enough
It’s one thing to get your ESP32 board working on the bench. It’s another thing to see how it behaves in the real world.
A product that seems stable in controlled lab conditions can fall apart when customers start using it every day.
That’s why you need to test early with your actual firmware, inside the final enclosure, and under conditions that mimic real-world use.
Run it in hot and cold environments, with batteries that are half drained, and next to other Wi-Fi devices to check for interference. Let it run for days, not just minutes.
These kinds of tests expose problems you’ll never catch in quick bring-up.
Maybe a current spike resets the board. Maybe heat buildup cuts your wireless range. Maybe a memory leak only shows up after 72 hours of continuous use.
If you don’t catch these problems before launch, your customers will. And that’s far more expensive to fix later than it is to test thoroughly now.
Mistake 9: Wrong GPIO Usage
The ESP32’s GPIO matrix lets you remap many signals, but not everything can be routed just anywhere.
For example, ADC inputs have to go to specific pins. Same with touch input, flash access, and strapping configuration.
If you assign one of these special pins to a general task like toggling an LED, you might break the boot process or corrupt flash reads.
The best approach is to start by identifying any fixed-function interfaces you need. I2C, SPI, UART, ADC, capacitive touch.
Lock those down first. Then use the remaining GPIOs for lower-priority tasks.
For some interfaces you’ll want to minimize routing distance so also consider that when selecting pins depending on the package.
