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.

Development

 NRF52840 Development Code

Data Sheets

AD7124-8 (pdf)

http://www.analog.com/en/design-center/design-tools-and-calculators/converter-tools.html