I Made a Reference Guide for AMB25 Because Realtek Forgot To 🤷‍♂️

I Made a Reference Guide for AMB25 Because Realtek Forgot To 🤷‍♂️

Hey devs! 👋

So, picture this: You just bought a shiny new development board. It's got dual-band WiFi, BLE 5.0, a beefy ARM Cortex-M33 processor, and it's Arduino compatible. You're pumped. You're ready to build the next big IoT thing. You crack open the documentation and... it's a mess. Scattered. Incomplete. You spend more time hunting for information than actually coding.

Sound familiar? Yeah, that was me with the AMB25/AMB26 (Realtek RTL8720DF) board.

So I did what any slightly frustrated developer would do — I made my own complete reference guide. And today, I'm sharing it with you!

🔗 The Repo

GitHub: https://github.com/nityam2007/AMB25-reference

Star it, fork it, contribute to it. Let's make this the resource that should have existed from day one.

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Wait, What's an AMB25 Anyway?

Great question! The AMB25 is a development board built around Realtek's RTL8720DF chip. It's actually pretty impressive for its size:

• CPU: ARM Cortex-M33 running at 200MHz (that's fast for a microcontroller!)
• RAM: 512KB
• Flash: 4MB (2MB available for your code)
• WiFi: Dual-band 2.4GHz AND 5GHz (802.11 a/b/g/n)
• Bluetooth: BLE 5.0
• Size: Tiny 50.7 × 17.8 mm form factor
• USB: Type-C (finally, a reversible connector!)

Think of it as an ESP32's cool cousin that nobody talks about at family gatherings.

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Why I Made This Reference Guide

Here's the thing about the AMB25 — it's genuinely a solid board. Dual-band WiFi is rare at this price point. BLE 5.0 is nice. The 200MHz processor is speedy. But the documentation? Let's just say it could use some love.

I found myself constantly jumping between:

• Forum posts from 2021 that may or may not still be relevant
• Scattered code examples that didn't compile
• Pinout diagrams that required a magnifying glass and a prayer
• API references that assumed you already knew everything

After the fifth time I had to search "AMB25 how to connect WiFi" and got five different answers, I snapped. Not in a bad way — in a "let me fix this" way.

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What's In The Reference Guide?

I tried to cover everything you'd actually need:

📍 Complete GPIO Reference

Every. Single. Pin. With actual useful information like:

• Which pins support PWM
• Which pins have ADC capability
• What each pin is shared with (so you don't accidentally fight over resources)
• Recommended pins for common use cases

Here's a taste of what the pinout table looks like:

Pin#	GPIO	ADC	PWM	UART	SPI	I2C
0	PA15				SPI1_SS
6	PA26		✓			I2C_SDA
7	PA25	✓				I2C_SCL
11	PB1	A4

No more guessing which pin does what!

📶 WiFi Examples That Actually Work

Both 2.4GHz and 5GHz examples. Station mode. AP mode. Scanning networks. Actually connecting to your home WiFi without it being a three-hour ordeal. All tested. All working.

🔌 Serial Communication

Did you know the AMB25 has THREE UART interfaces? I didn't! Until I dug through the datasheet at 2 AM. Now you don't have to:

• Serial — USB Serial (for Serial Monitor)
• Serial1 — Hardware UART1 (pins PB19/PB18)
• Serial2 — Hardware UART2 (pins PA12/PA13)

💾 Flash Storage

How to save data that survives power cycles using FlashMemory. Because sometimes you need to remember things.

🐛 Common Issues & Fixes

This section alone probably saved me hours of future frustration:

"Upload failed!" — Try holding the Burn button while pressing Reset, then release both. Now upload.

"Serial Monitor shows garbage!" — Set baud rate to 115200.

"WiFi won't connect to 5GHz!" — Make sure you're using the right channel. Some regions restrict certain 5GHz channels.

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My Favorite Discovery: Auto Upload Mode

Okay, so normally to upload code to the AMB25, you have to do this weird dance:

1. Hold the Burn button
2. Press Reset
3. Release both
4. Quickly click Upload in Arduino IDE
5. Hope you timed it right

But guess what? There's an Auto Upload Mode! Just enable it in Tools → Auto Upload Mode → Enable, and the board handles it automatically. Mind. Blown.

Why isn't this the default? Why wasn't this in big bold letters on the product page? I have no idea. But now you know!

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Code Snippet: Connect to WiFi

Here's a quick snippet to get you connected:

#include <WiFi.h>

char ssid[] = "YourNetworkName";
char pass[] = "YourPassword";

void setup() {
    Serial.begin(115200);

    WiFi.begin(ssid, pass);

    while (WiFi.status() != WL_CONNECTED) {
        delay(500);
        Serial.print(".");
    }

    Serial.println("\nConnected!");
    Serial.print("IP: ");
    Serial.println(WiFi.localIP());
}

void loop() {
    // Your awesome code here
}

Simple, right? That's the goal of the whole reference — make things simple and actually usable.

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Contributing

The reference is open source (obviously). If you find an error, have a better example, or discovered some hidden AMB25 magic — please contribute! Open an issue, submit a PR, or just leave a comment.

I especially want to hear about:

• Edge cases I haven't covered
• Projects you've built with the AMB25
• Things that confused you that I should clarify

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Final Thoughts

The AMB25/AMB26 is genuinely an underrated board. Dual-band WiFi, BLE 5.0, Arduino compatible, USB-C — it checks a lot of boxes. The only thing holding it back is documentation, and hopefully this reference guide helps fix that.

If you're working with these boards, give the guide a look. If it helps you, drop a star on the repo. If you find something wrong, let me know!

📚 Full Reference: https://github.com/nityam2007/AMB25-reference

Happy hacking! 🚀

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P.S. — If anyone from Realtek is reading this... please improve your docs. Love the hardware though. ❤️