nRF5340 Hardware
Nordic Semiconductor dual-core wireless SoC. The BCI receiver target for zig-syrup-bci.
Cores
| Core | CPU | Clock | Flash | RAM | Role | |------|-----|-------|-------|-----|------| | Application | Cortex-M33 + FPU + DSP | 128 MHz | 1 MB | 512 KB | User logic, DSP, crypto | | Network | Cortex-M33 | 64 MHz | 256 KB | 64 KB | Radio stack, BLE, Thread |
Cores communicate via IPC (inter-processor communication) with shared RAM regions and hardware mutexes.
Radio
- Frequency: 2400-2483.5 MHz (ISM band)
- Protocols: BLE 5.3, Thread 1.3, Zigbee 3.0, ANT, IEEE 802.15.4, proprietary 2.4GHz
- TX Power: -20 to +3 dBm (1 dB steps)
- RX Sensitivity: -98 dBm (1 Mbps BLE), -104 dBm (125 kbps coded PHY)
- Data Rates: 125 kbps, 500 kbps, 1 Mbps, 2 Mbps
- Direction Finding: AoA and AoD (antenna switching)
Key Peripherals
| Peripheral | Count | Notes | |------------|-------|-------| | GPIO | 48 pins (P0.0-P0.31, P1.0-P1.15) | 3.3V, 6 mA drive | | SPI | 4 (SPIM) | Up to 32 MHz, EasyDMA | | I2C | 4 (TWIM) | Up to 400 kHz | | UART | 4 (UARTE) | Up to 1 Mbps, EasyDMA, HW flow ctrl | | ADC | 1 (SAADC) | 12-bit, 8 channels, 200 ksps | | PWM | 4 | 16 MHz base, 4 channels each | | PDM | 1 | Digital microphone interface | | I2S | 1 | Audio codec interface | | QSPI | 1 | External flash, up to 96 MHz | | USB | 1 | Full-speed (12 Mbps), device only | | Crypto | 1 (CryptoCell-312) | AES, SHA, RSA, ECC, TRNG |
Power Domains
| Domain | Voltage | Peripherals | |--------|---------|-------------| | VDD | 1.7-5.5V | Main supply (internal LDO/DCDC to 1.1V) | | VDDH | 2.5-5.5V | High-voltage GPIO, USB | | DECN | 1.0-1.3V | Network core internal | | DECA | 1.0-1.3V | Application core internal |
Power modes: Active (6 mA), Idle (1 mA), System ON sleep (1.5 µA), System OFF (0.4 µA)
Use DCDC converter for battery operation — drops from ~6 mA to ~3 mA active current.
BCI Receiver Pin Assignment (zig-syrup-bci target)
| Pin | Function | Connected To | |-----|----------|-------------| | P0.06 | UART TX | Debug console | | P0.08 | UART RX | Debug console | | P0.13 | SPI SCK | fNIRS ADC (ADS1299) | | P0.14 | SPI MOSI | fNIRS ADC | | P0.15 | SPI MISO | fNIRS ADC | | P0.16 | SPI CS | fNIRS ADC | | P0.26 | I2C SDA | IMU (LSM6DSO) | | P0.27 | I2C SCL | IMU | | P1.00 | GPIO | LED status | | P1.01 | GPIO | Button (DFU trigger) | | P1.09 | ADC AIN5 | Battery voltage divider |
DFU Bootloader
The nRF5340 uses MCUboot as the default bootloader:
# Build with MCUboot
west build -b nrf5340dk/nrf5340/cpuapp -- -DCONFIG_BOOTLOADER_MCUBOOT=y
# Flash via J-Link
west flash
# DFU over BLE (using mcumgr)
mcumgr --conntype ble --connstring peer_name=nRF5340_BCI image upload app_update.bin
# DFU over USB (using nrfutil)
nrfutil dfu serial -pkg dfu_package.zip -p /dev/cu.usbmodem*
Zephyr RTOS
# Setup
west init -m https://github.com/nrfconnect/sdk-nrf
west update
# Build for application core
west build -b nrf5340dk/nrf5340/cpuapp app/
# Build for network core (BLE controller)
west build -b nrf5340dk/nrf5340/cpunet net/
# Flash both cores
west flash --erase
Key Kconfig Options
CONFIG_BT=y # Enable Bluetooth
CONFIG_BT_PERIPHERAL=y # Peripheral role
CONFIG_BT_DIS=y # Device Information Service
CONFIG_BT_NUS=y # Nordic UART Service
CONFIG_BT_CTLR=y # BLE controller on network core
CONFIG_IPC_SERVICE=y # Inter-core communication
CONFIG_HEAP_MEM_POOL_SIZE=8192
CONFIG_SYSTEM_WORKQUEUE_STACK_SIZE=2048
Relevant Datasheets
- nRF5340 Product Specification v1.3:
infocenter.nordicsemi.com/index.jsp?topic=%2Fps_nrf5340 - nRF5340-DK User Guide:
infocenter.nordicsemi.com/topic/ug_nrf5340_dk
Related Skills
| Skill | Connection | |-------|-----------| | zig-syrup-bci | BCI receiver firmware target | | cyton-dongle | 2.4GHz radio comparison (RFDuino vs nRF5340) | | opennirscap-build | fNIRS sensor connected via SPI | | nrf5340-device-interaction | Software/firmware interaction patterns |