Fruit Dendrometer

Dendrometer for fruit growth measurement

  • Attaches to the plant in seconds
  • Lightweight and will not damage the fruit or trunk
  • Installation resistant to wind and rain
  • Sizes to accommodate different sizes of fruit and trunks
  • Stable and adjustment-free operation
  • Real-time measurement of fruit and trunk growth
  • Swiss design and manufacture

Applications

Fruit crops

Measure fine-granularity climate to enable optimum irrigation

Greenhouses

Micro-climate measurement within greenhouses

Crop research

Maintain optimum germination conditions

Harvesting prediction

Determine crop readiness for harvesting

Yield improvement

Measure crop stress and ensure regular growth to avoid skin cracking

Technical data

Measurements

The fruit dendrometer measures the following:

  • Diameter
  • Temperature

The data is transferred via an I2C-bus interface. Multiple dendrometers as well as other sensors may be combined on the same bus and share a single radio transceiver hub to transfer data for monitoring and analysis.

There are two categories of I2C registers within the dendrometer:

  1. Ram registers: values which change often and are not saved after a reset.
  2. Flash registers: configuration values which are saved after a reset.

Writing to and reading from registers

Configurations registers are read-only by default.  ENABLE_MODE_CONFIG must be set to enable write-mode.

Packet format

Register Mapping

Ram:

Address Name Description Read/Write
0x00 DIAMETER_OUTPUT_L low byte diameter 0.01 mm/LSB R
0x01 DIAMETER_OUTPUT_H high byte diameter 0.01 mm/LSB R
0x02 TEMPERATURE_OUTPUT_L low byte temperature 0.1℃/LSB R
0x03 TEMPERATURE_OUTPUT_H high byte temperature 0.1℃/LSB R
0x06 START_MEAS write 1 to start measurement. always 0 when read R/W
0x7F ENABLE_MODE_CONFIG when set all addresses may be written W

Flash:

Address Name Description Read/write
0x8A CALIBRATION_OFFSET_L low byte offset on the diameter 0.01 mm/LSB R
0x8B CALIBRATION_OFFSET_H high byte offset on the diameter 0.01 mm/LSB R
0x8C TEMPERATURE_OFFSET_L low byte offset on the temperature 0.1℃/LSB R
0x8D TEMPERATURE_OFFSET_H high byte offset on the temperature 0.1℃/LSB R
0x8E DIAMETER_LIMIT_LOW_L low byte low saturation of the diameter 0.01 mm/LSB R/W
0x8F DIAMETER_LIMIT_LOW_H high byte low saturation of the diameter 0.01 mm/LSB R/W
0x90 DIAMETER_LIMIT_HIGH_L low byte high saturation of the diameter 0.01 mm/LSB R/W
0x91 DIAMETER_LIMIT_HIGH_H high byte high saturation of the diameter 0.01 mm/LSB R/W

The fruit dendrometer comprises:

  • Spring-loaded arm-assembly with integral sensors and signal conditioning
  • Screened cable
  • 4-pole waterproof connector (to connect to our transceiver unit or a bus-extender

Measurement

 Temperature Diameter
Units of measurement Degree Celsius mm
Resolution 0.1°C 0.01 mm
Precision +- 0.3°C +-0.05 mm
Range of measurement 0°C to 65°C 19mm to 90mm

Supply

  • 3.3V
  • 7.4mA (operating)

Initial configuration

Dendrometers are all delivered with a default I2C address. To combine multiple dendrometers on the same bus each needs to be re-programmed with a unique I2C address; this configuration may either be made at the time of ordering or programmed on-site prior to deployment.

Making measurements

To make a measurement

  1. Write 1 in the START_MEAS register
  2. Wait 50 ms for the measurement to be made
  3. Read the measurement (diameter, temperature) in the output register