Hardware: Hive Interface Board 5

After a failed attempt at Hive Interface board version 0.4, work has begun on version 0.5.

Analog Devices AD7124-8 Eval Board (left) connected to the Nordic nRF52840 Preview Development Kit (right)

A different approach from version 0.4 was taken. An Analog to Digital Converter (ADC) evaluation board (Analog Devices EVAL-AD7124-8SDZ) and the Nordic nRF52840 Preview Development Kit (PDK) were purchased.

This allows the software to be developed and tested before the hive interface board is designed. Initial development of the ADC driver was done on the PI.

Goal

Create a low power, battery operated, wireless scale based on the Internet of Things (IOT) paradigm with extended communication range and a high performance multi-channel Analog to Digital Converter (ADC).

Features

• AD7124-8 24 bit ADC with 8 differential inputs and digital filters capable of 120 dB notch at 50 Hz and 60 Hz.

Provides independent channels for each of the 4 load cells or four scales with 4 loads cells in parallel.

• Bluetooth Low Energy (BLE) support

Uses the Nordic nRF52 32 bit ARM processor with GPIO lines and eight 16 bit ADC inputs.

• 40 pin header plugs into a Pi.

The board can run from the Pi without the nRF52840 as a replacement for the HX711. The nRF52840 can be programmed from the Pi.

Configurations

Configuration A

Hive Interface Board plugged into the Pi.

• Powered by the Pi
• Sensors can be read by the Pi.
• Without optional nRF52840 installed, board can be operated like ver 0.3.
• nRF52840 (if installed) can be programmed from the Pi.
• Supports up to 8 load cells (4 scales consisting of 2 load cells each)

Configuration B

Hive Interface Board separate from the Pi. The Pi is used for data storage, visualization and forwarding to the cloud via WiFi, Ethernet or cellular modem.

• Lower power requirement at the hive.
• Communication to the PI is via UDP over BLE4.

Configuration C

• Pi is operated as BLE5/6LoWPAN to IP6 thread router using the nRF52840 radio since the Bluetooth radio on the Pi does not support BLE5 (only BLE4).
• Pi can also be used for local data storage and visualization.
• Hive Interface board uses BLE5 and 6LowPAN for long range low power consumption
• Three instrument boards

1. hive weight
2. Temperature/Relative Humidity and Microphone inside hive
3. Temperature/Relative Humidity and LUX outside hive (one per apiary).

• Can form a mesh network for data relay.

Development

 NRF52840 Development shows how to get Segger J-Link command line tools running on Linux Debian
 NRF52840 Development Code is a test program that runs on the nRF52840 and talks to the AD7124

Resources

Data Sheets

AD7124-8 Data Sheet (PDF 1.7 MB 92 pages)
nRF52840 (PDF 6.4 MB 696 pages)

AD7124-8 (pdf)

Evaluation Boards

EVAL-AD7124-8SDZ User Guide (PDF 4.8 MB 40 Pages)

nRF52840 Preview Development Kit v0.9.x User Guide v1.0 (PDF 9.1 MB 41 Pages)