OpenSprinkler OSPi User manual

OpenSprinkler Pi (OSPi) v1.4x User Manual
(Updated May 16, 2020)
Contents
Introduction
Hardware Interface
Hardware Setup
0. Preparation
1. Test Power Supply
2. Attach RPi to OSPi
3. Web Connectivity
5. Zone Expansion Board
6. Rain Sensor / Flow Sensor / Program Switch
7. Analog-Digital Converter (Advanced Topic)
8. Radio Frequency (RF) Transmitter (Advanced Topic)
Software Setup
1. Install OpenSprinkler Unified Firmware
2. Using OSPi Firmware
Technical Details
RPi Pin Uses
Specifications
Terms and Conditions
Open-Source Links

Introduction
OpenSprinkler Pi (OSPi) is an open-source sprinkler / irrigation extension board for the Raspberry Pi. It’s an easy and
low-cost solution to transform your Raspberry Pi into a capable sprinkler controller with unlimited number of stations, for
lawn and plant watering, farm irrigation and other similar applications.

The OSPi v1.4x kit includes a set of laser cut acrylic enclosure, one assembled and tested OSPi circuit board and terminal
blocks. The built-in components include 24VAC to 5VDC switching regulator, solenoid drivers, PCF8591T 8-bit ADC
converter (4 input and 1 output), per-station transient voltage protector. NOTE: from version 1.44, the real-time clock
(RTC) and battery that were in previous versions have been removed, as the firmware never uses these components.
To get started, you will also need the following, which are NOT included by default and need to be purchased separately.
●a Raspberry Pi (any version)
●a nano-size USB WiFi dongle (optional, if your RPi does not have built-in WiFi)
●a 4GB or above microSD card
●24V AC sprinkler transformer (output voltage 24V AC -- note that it’s AC, not DC!)
o Note: if you plan to use RPi 3 or 4: due to the rather high power consumption of these RPis, you may need an
additional USB adapter to power RPi directly through its microUSB port.
●24V AC sprinkler valves (note that it’s 24V AC valve, not DC or latching solenoid valve!)

Hardware Interface
The left image below marks the connectors and locations of various pinouts. The right image marks the locations of the
USB WiFi dongle and SD card after the Raspberry Pi is plugged in.

0. Preparation
OSPi 1.4x comes with a laser-cut acrylic enclosure. Enclosure assembly instructions can be found in this
Youtube Video. You can do so either before or after the following setup steps.
●From version 1.44, the real-time clock (RTC) and battery have been removed.
●If terminal blocks are pre-installed, you need to first remove all terminal blocks before assembling the
acrylic enclosure.
●In some kits, the acrylic pieces may be replaced by 3D printed versions (*this is due to shortage of acrylic
supply that occurred during the COVID-19 pandemic).
1. Test Power Supply First
Make sure the sprinkler transformer is unplugged to begin with. Insert the sprinkler transformer wires into the orange
terminal block, tighten the terminal block screws. Then plug the orange terminal into the matching terminal on OSPi. The
green LED should light up, indicating power is on. See pictures below.

Warning: if the LED doesn’t light up, please unplug the power immediately. If you can’t figure out the problem, contact the
support at support.opensprinkler.com


2. Attach RPi to OSPi
OSPi has two support pillars (positions marked in the left image below) that match the screw holes on RPi (except RPi 0
which doesn't have these screw holes). First, install the support pillars to the OSPi board (note: in some kits these
support pillars are replaced by 3D printed version, in which case just plug those in firmly into the OSPi board); then, plug
RPi into OSPi through the 2x20 pin headers, with SD card slot facing the left, and USB and Ethernet jack facing the right.
Double check the orientation and make sure all pins are aligned. Any misalignment may result in damage to RPi. The two
screw holes should also match the support pillars. Insert RPi all the way to the end. The USB and Ethernet connector
should go through the cutouts on the PCB.
3. Web Connectivity
OSPi fits a nano-size USB WiFi dongle. You can insert the dongle into any of the available RPi USB ports. If you prefer
wired connection, note that there is no special cutout for the Ethernet cable, you can take out one side panel of the
laser-cut acrylic enclosure, or alternatively use a Dremel to make a cutout yourself, in order to allow Ethernet cable to pass
through.

If you use RPi 3 or 4 and notice dropped performance of built-in WiFi, you probably need to use a separate USB power
adapter to power it directly from its microUSB port. You can take out one of the side panels to allow the microUSB cable
to pass through.
4. Wiring Sprinkler Valves
To connect a sprinkler valve, insert one wire to the COM (common) terminal, and the other wire to any of the station
terminals (1-8). The COM terminal has two ports – they are internally connected so either port is fine. To connect multiple
valves, one wire from each valve should come together and go to the COM terminal; and the other wire from each valve
goes to an individual station terminal. See the diagram below.

5. Zone Expansion Board
To connect a zone expansion board, use the extension cable you received to
link the OSPi’s OUT port to the expansion board’s IN port. The connector on the
cable is polarized (with a bump on the top), so there is only one way to plug it.

If you have multiple expansion boards, you can daisy chain them in the same
way, by following the OUT -> IN links.

When using zone expansion boards, the sprinkler valves are wired the same
way as before: one wire from each valve should come together and go to the
COM terminal on the OSPi; and the other wire from each valve goes to an
individual station terminal.
6. Rain Sensor / Flow Sensor / Program Switch
If you have a rain sensor, you can connect it to OSPi via the rain sensor terminal. The rain sensor has two wires and is
essentially a rain-activated switch. The OSPi software can decide what to do when rain is detected, such as turn off
stations or ignore rain. The latest OpenSprinkler also supports using the sensor terminal to connect a flow sensor, or
program switch. Please refer to the OpenSprinkler User Manual Sensors Section for details.
7. Analog-Digital Converter (Advanced Topic)
OSPi has a built-in PCF8591T A/D D/A converter, which provides four 8-bit analog inputs, and one analog output. The
analog inputs can be used to read analog sensors, such as light, temperature, soil humidity. Details on how to use this
converter can be found in this blog post.
8. Radio Frequency (RF) Transmitter (Advanced Topic)
The current OSPi has a 3-pin header that fits a 433MHz or 315MHz radio frequency (RF) transmitter. This allows you to
use OSPi to communicate with RF wireless power sockets. Please refer to the OpenSprinkler User Manual RF Transmitter
Section for details.

Software Setup
1. Install OpenSprinkler Unified Firmware
The recommended way to install OpenSprinkler Firmware is to start from a standard Raspbian image, make sure you can
boot RPi correctly, then follow the OSPi firmware installation instructions below to install the firmware yourself:
●OSPi Firmware Installation Instructions
NOTE: some Raspbian systems installed by NOOBs will take over GPIO 4 for 1-wire interface, but that OSPi needs GPIO 4
to send control signals to the solenoid valves. If you found that the firmware runs correctly but OSPi does not turn on
valves correctly, one solution is to sudo open /etc/modules, and comment out the line containing w1-gpio, then reboot.
Another solution is to reinstall Raspbian OS from scratch without using NOOBs.
The previous OSPi pre-configured SD card image is retired -- we no longer provide pre-configured SD card image because
it's relatively easy to install a fresh Raspbian and follow the instructions above to install the OpenSprinkler firmware.
2. Using OSPi Firmware
The default firmware set to run on start-up is the OpenSprinkler Unified Firmware. It’s available at port 8080. Open a
browser, and type in http://ospi_ip:8080/ to start using the firmware, where ospi_ip is your OSPi's local IP address. Details
about the OpenSprinkler Unified Firmware can be found in the OpenSprinkler Firmware User Manual:
●OpenSprinkler User Manual
The two alternative firmwares are the Python Interval Program (written by Dan Kimberling) and the sprinklers_pi program
(written by Rich Zimmerman). Please refer to their specific Github repositories for installation and usage instructions.
If you want to write your own firmware, use the provided firmwares as starting point. In addition, in the OSPi Github folder,
there are a few demo programs that shows basic solenoid control in various programming languages.

Technical Details
RPi Pin Uses
OSPi uses the following GPIO pins on the RPi (shaded in red). The other pins are free. The power pins as well as SDA/SCL
pins can be shared with other devices. All 40 pins from RPi are mapped out in the pinout area at the upper left corner of
the circuit board. The layout of the mapped out pins match the GPIO pins. Pins use by OSPi is marked by a white outline.

Specifications
●Input Voltage: 22V AC to 30V AC.
●DC Output Current: 500mA @ 5V (to power RPi).
●Number of Zones: 8 on the OSPi, expandable by linking zone expansion boards.
●AC Output Current: 800mA continues @ 24V AC per zone / station, 8A impulse / inrush.
●Over-voltage Protection: 48V bi-directional TVS on each zone, AC input, and rain sensor terminal.
●Size: 135mm x 100mm x 32mm (5.3” x 4” x 1.26”)
●Weight: 150g (5.3oz) w/o RPi

Terms and Conditions
OpenSprinkler Pi (OSPi) is an open-source project. The hardware design and software code are made publicly available
under the Creative Commons Attribution-ShareAlike (CC BY--SA) 3.0 license. The product is open-source for educational
purpose and to promote innovations. The hardware and software are provided as is. We (Rayshobby LLC) are not
responsible for any damage or accident that may occur due to hardware or software error, or during the assembly, use,
and modification of OSPi.

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Open-Source Links
●OSPi Github Repository
●OpenSprinkler Firmware Github Repository
●OSPi homepage