skylin008 / microsdi12

A mini SDI-12 implementation for getting sensor info over RS-485

microSDI12

A mini SDI-12 implementation for getting sensor info over UART using directional RS-485.

API

class SDI12

_init_ (pin_txd, pin_rxd, pin_direction, uart_bus_id)

• TX pin name
• RX pin name
• Direction pin name (optional)
• UART bus id (optional, default = 1)

is_active (address)

• args:
  • SDI-12 sensor address. Typical range: 0-9.
• returns:
  • Boolean: whether the sensor has send back acknowledgment

get_sensor_info (address)

• args:
  • SDI-12 sensor address. Typical range: 0-9.
• returns:
  • Tuple (manufacturer, model): The manufacturer and model name as reported by the sensor. If sensor is unreachable, returns (None, None)

get_measurement (address, measurement_name="M")

Sends a request for data measurement to the sensor and returns the data provided by the sensor split into an array. Supports parsing all possible values provided through multiple sequential requests on the sensor. Example:

  > aM!
  < a1329 (address + max 132 seconds of waiting + 9 expected values )
  > aD0!
  < a+1+2-3+4.1+5 (5 values read so there will be an additional request for extra data)
  > aD1!
  < a+6+7+8+9

  output: [1, 2, -3, 4.1, 5, 6, 7, 8, 9]

• args:
  • SDI-12 sensor address. Typical range: 0-9.
  • measurement_name: Configures the name of the query. Default is "M" as the default query is "aM!".
• returns:
  • Measurement data array: an array containing all the data collected from the sensor. For details on each data value, please advise sensor manufacturer manuals. If sensor is unreachable, returns None

Example

from microsdi12 import SDI12

sdi12 = None

try:
    sdi12 = SDI12("P3", "P4", "P8", 1)

    manufacturer = None
    model = None
    sensor_response = None
    address = "1"

    if sdi12.is_active(address):
        manufacturer, model = sdi12.get_sensor_info(address)
        response_array = sdi12.get_measurement(address)
        print(response_array)
except Exception as e:
    print("Exception while reading SDI-12 data")
finally:
    if sdi12:
        sdi12.close()

links

• https://docs.micropython.org/en/latest/library/machine.UART.html
• https://docs.pycom.io/firmwareapi/pycom/machine/uart/