SparkFun NAU7802 Load Cell Amplifier 24 Bit

The SparkFun Qwiic Scale carries the 24-bit A/D converter NAU7802 and reads load cells via I2C. The load cell is connected solder-free to the spring terminal, and the two Qwiic connectors allow the board to be daisy-chained with other I2C devices without soldering. This makes it possible to build scales, process controls or presence detection. Compared with the HX711, the NAU7802 has a true I2C interface.

Note: Load cells with 4 wires are full bridges and are connected directly. Half-bridge cells with 3 wires such as the 50kg load cell are wired in groups of four to form a full bridge.

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Features:

24-bit A/D converter with programmable gain and 2 channels
True I2C interface, 2 Qwiic connectors for daisy-chaining
Spring terminal for the load cell, according to SparkFun for wires AWG20 to AWG26
INT pin signals a new reading, data rate 10, 20, 40, 80 or 320 Hz
AVDD pin brings out the load cell supply, 3.3 V by default, according to SparkFun not to be used as a current source
I2C solder jumper disconnects the 2.2 kΩ pull-up resistors
On-chip temperature sensor

Application Examples:

Scales for kitchen, parcels or beehives
Monitor container levels via weight
Process control and presence detection

Documentation:

Technical Data:

Chip: NAU7802
Operating voltage: 2.7 V to 5.5 V, 3.3 V via Qwiic
Resolution: 24 bit, 2 channels
Data rate: 10 to 320 Hz
External differential reference voltage: 0.1 V to 5 V
Standby current: below 1 µA
Connections: GND, 3V3, SDA, SCL, INT, AVDD, 2× Qwiic
Load cell connection: terminals GRN, WHT, BLK, RED. Load cell usually: red to RED (E+), black to BLK (E-), white to WHT (A-), green to GRN (A+). If the reading falls under load, swap A+ and A-
Dimensions: 35.5 × 26 × 17 mm
Weight: 6.5 g