This video explores "stamp-sized" ESP32 development boards, inspired by the Seeed Studio XIAO form factor. The creator tests various versions, including those based on the ESP32-C3 and ESP32-S3 chips, highlighting their compact size, USB-C connectors, and integration of power management circuitry. A key focus is the performance comparison of different antenna types, specifically PCB antennas versus tiny chip antennas, through a range test conducted at increasing distances (25m, 125m, 150m). The video discusses pinout variations, the lack of an onboard USB-to-serial converter on some models necessitating a specific boot procedure for programming, and notes features like castellated pins and battery charging support on certain boards. Despite some minor manufacturing inconsistencies and challenges with programming models lacking the USB-to-serial chip, the creator concludes that these miniature boards are very capable and will be useful for future projects, particularly noting the surprisingly good range of the chip antennas.
Shrinking Your Projects: A Look at Stamp-Sized ESP32 Boards
0:05 Stamp-sized ESP32 boards: The video introduces compact ESP32 development boards inspired by the Seeed Studio XIAO form factor, highlighting their small size and inclusion of essential features like power management and USB-C.
1:40 USB-to-Serial: Newer ESP32 chips (C3, S3) have native USB support, allowing some of these small boards to omit the external USB-to-serial converter chip found on older development boards.
1:54 XIAO Form Factor: The Seeed Studio XIAO boards set a standard for this miniature size, offering a consistent pinout and features. Other manufacturers have copied this format, though not always exactly.
2:35 Castellated Pins: Many boards feature castellated pins, allowing them to be soldered directly onto another PCB like a module.
2:42 Limited Pins: Due to the small size, these boards expose fewer pins (typically around 16) compared to standard development boards, with some pins left unconnected.
3:06 Pinout Variations: While the XIAO series has a standard layout, other manufacturers have slight variations, particularly concerning the position of the USB VBUS and 3.3V pins.
4:03 Manufacturing Quality: Most boards tested showed decent manufacturing quality, though one cheap ESP32-C3 board was unusable.
4:35 Antenna Types: The video focuses on comparing PCB antennas (standard on larger boards) and the tiny chip antennas used on many of these small boards.
5:08 Antenna Selection: Boards with both PCB and chip antenna options typically use a zero-ohm resistor, a solder jumper, or software configuration to select the active antenna.
6:09 Wi-Fi Range Test Setup: A test setup was created using one board as a "receiver" and the others as "devices under test" to measure Wi-Fi packet loss at increasing distances. Channel 6 (2.437 GHz) was chosen for testing due to its central position in the Wi-Fi spectrum.
7:28 Range Test Results: Testing started at 25 meters, where all boards performed well except the faulty one. At 125 meters, only boards with chip antennas successfully connected. At 150 meters, only one board (an ESP32-S3 with a chip antenna) maintained a connection, demonstrating surprisingly good range from the chip antennas.
8:44 Chip Antenna Performance: The tiny chip antennas performed surprisingly well in the range test, even outperforming some PCB antennas in challenging conditions. They do seem to have some directionality.
9:35 Programming Boards without USB-to-Serial: Boards lacking a dedicated USB-to-serial chip require enabling the chip's native USB CDC functionality for programming, typically done by holding the boot button during power-up or reset. This can sometimes be tricky.
10:40 Battery Support: Some boards include battery connectors and charging circuitry (Li-Ion 3.7V).
10:56 Breakout Boards: Adapter boards are available to convert the small form factor to a breadboard-friendly pin header layout, though they add size.
11:50 Key Takeaways: These boards are stamp-sized, capable, and useful. Using through-hole or adapter boards makes them easier to prototype with. There are different sizes and layouts, but the XIAO series offers standardization. Chip antennas perform well and have some directionality. Boards without a USB-to-serial chip require enabling USB CDC for programming.
13:23 Conclusion: The creator finds these miniature boards very capable and plans to use them in future projects, partly due to their surprising Wi-Fi range with chip antennas.