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Seeed Studio XIAO nRF52840 is equipped with a powerful Nordic nRF52840 MCU which integrates Bluetooth 5.0 connectivity. Meanwhile, it has a small and exquisite form-factor which can be used for wearable devices and Internet of Things projects. The single-sided surface-mountable design and the onboard Bluetooth antenna can greatly facilitate the rapid deployment of IoT projects.
In addition, there is an advanced version of this board, Seeed Studio XIAO nRF52840 Sense. It is integrated with two extra onboard sensors. One of them is a Pulse Density Modulation (PDM) Digital Microphone. It can receive audio data in real-time which allows it to be used for audio recognition. The other one is a 6-axis Inertial Measurement Unit (IMU), this IMU can be very useful in TinyML projects like gesture recognition. These onboard sensors provide a great convenience for users while the board is ultra-small.
The newly upgraded XIAO nRF52840 Plus and XIAO nRF52840 Sense Plus provide considerable increases in functionality and usability. The number of multifunctional pins has been increased to 20, I2S and SPI resources have been added to support more complex projects, NFC pins have been exposed for easier integration into IoT and smart card applications, and the BAT pin has been repositioned for better soldering convenience, resulting in a more user-friendly hardware experience.
Compared to Seeed Studio XIAO RP2040, Seeed Studio XIAO nRF52840 contains richer interfaces. The first thing to note is that the Near Field Communication (NFC) interface is functional on the board. Secondly, there is a tiny reset button on the side of the Type-C interface. On the other side, there is a 3-in-one LED (User LED) along with a Charge LED to indicate the charging status when a battery is connected. There are 11 digital I/O that can be used as PWM pins and 6 analog I/O that can be used as ADC pins. It supports all three common serial interfaces such as UART, I2C, and SPI. Same as Seeed Studio XIAO RP2040, it has an onboard 2 MB flash which means it can also be programmed using Arduino, MicroPython, CircuitPython, or other programming languages.
Seeed Studio XIAO nRF52840 Sense is compatible to the Seeed Studio XIAO expansion board.
Powerful wireless capabilities: Bluetooth 5.0 with onboard antenna
Powerful CPU: Nordic nRF52840, ARM® Cortex®-M4 32-bit processor with FPU, 64 MHz
Ultra-Low Power: Standby power consumption is less than 5μA
Battery charging chip: Supports lithium battery charge and discharge management
Onboard 2 MB flash
Onboard PDM microphone (only in Seeed Studio XIAO nRF52840 Sense)
Onboard 6-axis LSM6DS3TR-C IMU (only in Seeed Studio XIAO nRF52840 Sense)
Ultra Small Size: 21 x 17.8mm, Seeed Studio XIAO series classic form-factor for wearable devices
Rich interfaces: 1xUART, 1xI2C, 1xSPI, 1xNFC, 1xSWD, 11xGPIO(PWM), 6xADC in XIAO nRF52840 (Sense); and 2xUART, 1xI2C, 2xSPI, 1xI2S, 1xNFC, 1xSWD, 18xGPIO(PWM), 6xADC in XIAO nRF52840 (Sense) Plus
Single-sided components, surface mounting design
Processor
Nordic nRF52840, ARM® Cortex®-M4 32-bit processor with FPU, 64 MHz
Wireless Connectivity
Bluetooth 5.0/BLE/NFC
Memory
256 KB RAM,1MB Flash 2MB onboard Flash
Built-in Sensors
N/A
6 DOF IMU (LSM6DS3TR-C), PDM Microphone
N/A
6 DOF IMU (LSM6DS3TR-C), PDM Microphone
Interfaces
1xI2C, 1xUART, 1xSPI
1xI2C, 2xUART, 2xSPI, 1xI2S
PWM/Analog Pins
11/6
20/6
Onboard Buttons
Reset Button
Onboard LEDs
3-in-one LED/ Charge LED
Battery Charge Chip
BQ25101
Programming Languages
Arduino/ MicroPython/ CircuitPython
Seeed Studio XIAO nRF52840 assembles many functions in one tiny board and sometimes may not perform the best of them. Hence, Seeed has published two Arduino libraries to let it maximum the power of each function. Therefore:
It is recommanded to use the Seeed nRF52 Boards library if you want to apply Bluetooth function and "Low Energy Cost Function".
It is recommanded to use the Seeed nRF52 mbed-enabled Boards library if you want to use it in embedded Machine Learning Applications or apply "IMU & PDM advanced function".
Both libraries support very well when it comes to the basic usage, such as LED, Digital, Analog, Serial, I2C, SPI.
The Pin definition supported by these two libraries might be a little different and Seeed will keep update the wiki until it is clear.
tip:
If you prefer a simpler approach, you can choose Seeed nRF52 mbed-enabled Boards from the beginning. It supports the compilation of the Serial function without the need for additional modifications.
If you use the onboard package of Seeed nRF52 Boards, the Serial function may not compile. The solution is to add the line "#include <Adafruit_TinyUSB.h>" in your code. You can download this package from:
