Hardware: PCB Assembly

Dev Kit PCB installed on a Pi 2.

Parts

Parts List

Mechanical Drawing for RJ connectors.

Board Layout Version 0.2

• 

  Connectors.

• 

  Console and 12 V power supply option 1.

• 

  Spare GPIO, I2C and I2S headers.

Assembly

40 pin header

1. Insert the 2x20 female header from the bottom side of the board, tack two pins, and check that the header is all the way down on the board and is straight.

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  1.1 Insert the header from the bottom.

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  1.2 Solder one pin on each end.

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  1.3 Check the connector for alignment.

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  1.4 Melt solder and straighten.

2. After checking and adjusting alignment, solder the rest of the header pins on the top (component, silk screen) side of the board.

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  2.1 Solder the rest of the pins.

Resistors

Insert the resistors in the board. If you do not plan to monitor a 12 volt supply, you may not need R2-R5. If you do not plan to use a rain gauge, you may not need R6.

Number	Value (Ohms)	Purpose
R1	330	Controls brightness of LED
R2	200K	12 V monitoring voltage divider
R3	1K	12 V monitoring voltage divider
R4	2.2K	12 V monitoring Reference voltage divider
R5	2.2K	12 V monitoring Reference voltage divider
R6	1K	Rain gauge input filter

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  2.1 Insert the resistors.

Male headers

Required

1. H8 1x4 and H9 1x6 for the HX711 board.

Optional

1. H4 1x4 for console serial port
2. H2 1x5 for I2C
3. H6 1x5 for spare GPIO
4. H7 1x7 for I2s
5. 4 1x2 for 12 V power supply option 1.

• 

  1.2

Capacitors

Number	Value (Ohms)	Purpose
C1	4.7 mfd. Electrolytic	Power supply filter.
C3	0.1 mfd Tantlum	Rain gauge filter.

RJ1 and RJ2

Place the 4 port RJ jack on the top of the board, carefully aligning the longer latch pins on each side into the holes. Holding the RJ jack on the board, turn the board over and inspect the 16 leads. Make sure that each one is lined up with a hole. If all the pins are lined up, press the connector in on each end and snap it in place.

Be very careful to check that all the leads are in the holes before you snap it in and solder it.

Install the HX711 board

1. Install C1 4.7 mfd. Observe polarity.
2. Insert the 1x4 and 1x6 female headers on the make headers.
3. Install the HX711 board on the 1x4 and 1x6 female headers.

LED

1. Install LED D1.

1. Install C3 .1 mfd. for rain gauge filter.

12 VDC power supply if used.

Power Supply Option 1: D-SUN

1. Install four 1x2 male headers.
2. Install blue screw terminal block.
3. Install four 1x2 female headers on the four 1x2 male headers.
4. Install the Power Supply board on the four 1x2 female headers.

WARNING: If you use the D-SUN 12 volt power supply it must be adjusted before you plug the board into the Pi! Failure to set the output of the 12 v supply to 5 volt will fry the Pi, SD card, USB peripherals.

Power Supply Option 2: Fulree

1. Install Fulree voltage regulator
2. Install green spring terminal block.

Testing

If using Power Supply Option 1, the voltage must be adjusted to 5.0 to 5.1 volts before connecting to the Pi or HX711 board.