1-Wire Outdoor Sensor/Interface Kit


Errors take two forms, the kind that damage components and the kind that don't. Neither is desirable, but the type that damages components will require you to find a replacement part. Before connecting the board for the first time, check the following:

  Polarity of the tantalum capacitor. The negative lead is usually identified with a white stripe and a big minus sign on it. The positive lead is identified on the PC board. Not all the capacitors have the same orientation; double-check them with reference to the PC board silkscreen.
  Polarity of diodes D1 (if installed), D2 and D3. The band on the diode should align with the extra stripe on the PC board silkscreen.
  If installed, the orientation of the integrated circuits with pin 1 correctly oriented to the dot, notch or bevel outline on the PC board.
  NO shunts are installed at JMP1 (T, G/E, H).

Stop! In the following, the unit will be connected to the X1W-1 only. If your final configuration will use the T-238, it must be disconnected for these tests. If you did not purchase or have the X1W-1, then skip to the final installation. Otherwise, continue below.

1-Wire Cable

If you did not read the section on 1-Wire cables on the AAG page, do so now before proceeding. You have been warned!

Voltage Checks

Be Alert! Observe anything unusual such as components heating up, smoke or smell. If anything unusual appears, immediately turn off the power. Find and correct all problems before continuing.

The next two steps apply to the X1W-1 (inside board)
  Be certain push-on shunts are installed at Ext 5V (P17) and 1W PU (P18)
  Remove all push-on shunts at JMP1 except Ser. To put it another way, only the Ser shunt should be installed at JMP1.
  Using the proper 1-Wire® cable (see above), connect the X1W-1 and X1W-2 together.
  Apply power to the X1W-1 (inside board).
Continuing on the X1W-2...
  Place the ground lead of your voltmeter on the anode (opposite the banded end) of D2. This is ground reference for all measurements.
  Measure the voltage on the Ext 5V bus by connecting the other lead of the meter to the cathode of D2. This should be 5 volts, ±0.25V. If not, fix the problem before proceeding.
  Approximately 5VDC on pin 5 of U5 (the DS2438)
  Positive DC voltage at pin 4 of U5 (DS2438) in the range of 1 to 4 volts. This is the DC output of the humidity sensor. Be careful not to slip the probe and short the pins.
  Remove power from the circuit.

If you failed to get these voltages, find the problem before proceeding!

Verify 1-Wire Operations

You will need the various 1-Wire utilities on your PC for these tests. If you have not already done so, download and extract them before proceeding.

In this section you will verify that all the 1-Wire devices are responding and functioning using the the tstfind utility.

The push-on shunts are used to enable/disable the 1-Wire® sensors. The main use of this feature is for sensor setup in the T-238 firmware and trouble-shooting. Install the following push-on shunts as required at JMP1.

  Install push-on shunts at H and T
Perform the following step only if the EMP/rain gauge interface is installed...
  Install a push-on shunt at G/E
  Connect a standard DB9 M-F serial cable from a COM port on your PC to the X1W-1 (inside board).
  Reconnect DC power to the X1W-1.
  At the command prompt, run the 1-Wire tstfind utility. 
For Linux, the command is (Note the leading dot!)
./tstfind  /dev/ttySn
where n is the serial port you are using. Example: /dev/ttyS2 
For Windows, enter
tstfind  COMn
where n is the COM port you are using. Example: COM1

Use this command format for all the utilities in the following tests.
  tstfind should find the 1-Wire serial adapter and list the serial numbers for two (or three) other devices. The last two digits of the serial number indicate the type of device. See the table below. You should see a temperature sensor and the A/D. If the EMP/rain gauge option is installed, there should also be a counter. Press CTRL-C to stop tstfind.
Digits Device Type
10 Temperature (DS18S20)
26 A/D (DS2438)
1D Counter (DS2423) Only present if EMP/Rain Gauge option installed

If tstfind fails to find these devices, check jumpers, solder connections, component orientation, etc. until you find the problem before proceeding.

Temperature (DS18S20)

Preparation: none

While the program is running: no action required

Utility Results
temp temp should repeatedly list the serial number and the temperature.

A/D (DS2438)

The DS2438 A/D converter is used for the HIH-4000-001 humidity sensor.

Preparation: none

While the program is running: no action required

Utility Results
gethumd gethumd will list the humidity, temp, supply and sensor volts out. The supply voltage should be around 5 volts.

Stop! The next section is only completed if the EMP/Rain Gauge option is installed on the board. If you do not have this option, proceed to the final assembly. Otherwise, continue below.

Counter (DS2423)


  Remove power from the board, if you have not already done so.
  Connect a 9V battery to the battery connector.
  Connect the rain gauge to the board at J3.
  Locate the extra 100 ohm resistor supplied with the kit to use in the procedure that follows.
  Apply power to the board.

While the program is running: occasionally tip the bucket in the rain gauge.

Likewise, use the 100 ohm resistor to periodically make the connection between the center pin and ground on the RCA phono jack (EMP detector input). As a convenience, the upper right-hand corner mounting hole is ground for the jack.

Utility Results
counter counter should list the serial number and both counter contents. Verify that the counters change when you tip the bucket and make the connection to the center pin of the RCA phono jack through the 100 ohm resistor. Note that only the last two columns will change.

Congratulations! This completes the testing phase.