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nRF52 General Overview

Nordic Semiconductor is a company established in Norway that develops and produces very interesting electronic elements capable of transmitting data with radio signals. In their portfolio, among other advanced chips, there is the nRF52 family of SoCs, which support low-power radio communication with chosen popular protocols including Bluetooth Low Energy, ZigBee, NFC, Matter and Thread. They achieved high popularity due to low power consumption possible because of the implementation of an advanced, adaptive power management system. There are a few versions of chips which support different combinations of protocols. The simplest nRF52805 supports BLE only, while the most advanced nRF52840 is a fully multiprotocol chip with all previously mentioned standards support.

Hardware

Nordic Semiconductor's series of SoCs includes a powerful and efficient ARM® core that together with advanced power management allows to create advanced projects with ultra-wol power consumption. All SoCs include Flash memory for programs eliminating the need for connecting the external memory. Flash can be programmed during production, but also can be re-programmed after implementation in a ready product with OTA (Over The Air). There are some development boards available for nRF52 series SoCs. Nordic Semiconductor produces development kits for nRF52, nRF52833 and nRF52840. For the last one, there is also a USB dongle. Other companies also offer their own development boards for the nRF52 series with very interesting Arduino Nano 33 BLE, Adafruit Feather nRF52 Bluefruit LE, and Adafruit Feather nRF52840 Sense among them.

Processor

All nRF52 SoCs are built with 64 MHz ARM® Cortex-M4 core working at 64MHz of clock. The main processor is supported by a floating point calculation unit (FPU).

RAM memory

Different versions contain different sizes of RAM and Flash memory. The nRF52805, nRF52810, and nRF52811 have 192kB of Flash and 24 kB of RAM. The nRF52820 has 256kB of Flash and 32 kB of RAM. The nRF52832 can have 256 or 512 kB of Flash and 32 or 64 KB of RAM, depending on the version. The nRF 52833 has 512 kB of Flash and 128kB of RAM, and the nRF52840 has 1MB of Flash for the program and 256kB of RAM for data.

Networking

The nRF52 family was developed to support low-power radio communication using a 2.4GHz band. This set of protocols includes Bluetooth 5.4, Thread, Matter, Zigbee, and Bluetooth Mesh. nRF52 family of SoCs does not support WiFi directly or wired Ethernet network protocol. To achieve such functionality, it is necessary to use a network chip connected via SPI.

Peripherals

The nRF SoCs are equipped with a reach set of peripherals including:

  • GPIO – General Purpose Input Output lines
  • TWI – Two Wire interface that can work in both master or slave mode
  • SPI – Serial Peripheral Interface working in master or slave mode
  • UART – Universal asynchronous receiver/transmitter
  • Timer – timer/counter unit
  • RTC – Real-time counter
  • WDT – Watchdog timer

In selected models also additional units are available:

  • QSPI – Quad SPI and high-speed SPI in some versions
  • I2S – Inter-IC sound interface
  • USB – Universal serial bus device
  • PDM – Pulse Density Modulation (PDM)
  • PWM – Pulse Width Modulation
  • COMP – Analog comparator with low power version LPCOMP
  • SAADC – Successive approximation analog-to-digital converter

All peripherals are connected to the processor via PPI (Programmable Peripheral Interconnect) ensuring flexible use of units. Peripherals have input signals Task that trigger their operation and output signals Event which inform of some situation. These signals can be connected together creating hardware dependencies between units which make it possible to synchronise the operation of peripherals without the need for processor use. Some units can be handled with an internal DMA mechanism (EasyDMA) that supports data transmission between peripherals and memory without code execution. To enable safe wireless transmission some cryptographic hardware units are included:

  • RNG – Random Number Generator
  • ACL – Access contol list
  • AAR – Accelerated address resolver
  • CCM – Cipher block chaining - message authentication code
  • ECB – AES electronic codebook
  • Cryptocell

The Cryptocell is a special security subsystem developed by ARM® which provides the root of trust (RoT) and cryptographic services for a device.

Hardware summary

Version nRF52805 nRF52810 nRF52811 nRF52820 nRF52832 nRF52833 nRF52840
Bluetooth 5.4 Yes Yes Yes Yes Yes Yes Yes
Bluetooth Mesh Yes Yes Yes Yes
Thread Yes Yes Yes
Matter Yes
ZigBee Yes Yes Yes
Flash size [kB] 192 192 192 256 256/512 512 1024
RAM size [kB] 24 24 24 32 32/64 128 256
FPU Yes Yes Yes
Advanced SPI High speed High speed, QSPI
USB Yes Yes Yes
Analog ADC ADC, Comp ADC, Comp Comp ADC, Comp ADC, Comp ADC, Comp
Others PWM, PDM PWM, PDM PWM, PDM, I2S PWM, PDM, I2S PWM, PDM, I2S
No. of GPIOs 10 15-32 15-32 18 32 18-42 48

Nordic Semiconductor created development boards for their SoCs. The most popular is nRF52840 DK which includes the nRF52840 chip, SEGGER J-Link debugger, the micro USB port for flashing, debugging and serial data communication, four user buttons, and four user LEDs. The board has a shape similar to Arduino with all 48 GPIOS available at the header connectors and is shipped with an NFC antenna. [✓ pczekalski, 2023-10-02] upload nRF52840 DK photo

Figure 1: nRF52840 DK development board

Another board created by Nordic Semiconductor is a USB dongle with the same nRF52840 SoC built-in. It doesn't have a debugger but supports uploading the code via USB using the bootloader. It has 15 GPIO lines available. upload nRF52840 dongle photo

Figure 2: nRF52840 USB dongle

The very interesting board was developed by Adaftuit. It contains the nRF52840 SoC and a set of different sensors, making it useful for developing sensor devices with wireless connectivity. Additionally, this board has a Li-Po battery charger built-in, and digital RGB LED. Sensors include:

  • LSM6DS33 accelerometer and gyro
  • LIS3MDL magnetometer
  • APDS9960 proximity, light, colour and gesture sensor
  • MP34DT01-M microphone
  • SHT-30 humidity sensor
  • BMP280 temperature and air pressure sensor

[✓ pczekalski, 2023-10-02] upload nRF52840 Feather photo

Figure 3: Adafruit nRF52840 Feather Sense
en/iot-open/hardware2/nrf52.1696247328.txt.gz · Last modified: 2023/10/02 11:48 by ktokarz
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