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OpenSprinkler Hardware Release Notes

Version 2.1u
  • ATmega644 running at 12MHz (previously 8MHz).
  • Removed ATtiny45; ATmega644 is flashed with USBasp bootloader.
  • Added solder-on fuse on 24VAC line.
  • Added per-station MOV (for projection against transient voltages).
  • Added on-board 5V mini-relay.
  • 24VAC screw terminal changed to an orange colored on with 4mm pin spacing.

Version 2.0s
  • Microcontroller changed to ATmega644.
  • Added microSD card slot, .
  • Switching regulator upgraded to LM2596S-5.0 (from MC34063 previously)
  • Added support for LCD backlight and contrast adjustments
  • Added pull-up resistor (RPR) for automatic detection of extension board.
  • More digital and analog I/O pins, and extra pin headers for connecting RF transmitter.

Version 1.42u / 1.4s
  • Added one 5.6V zener diode and removed the PTC fuse.
  • Changed capacitor CT to 100pF in order to reduce switching regulator noise.
  • Combined four 10K resistors from 1.4u to one 10Kx4resistor network.
  • Switching positions of rain sensor terminal and zone expansion connector. Expansion connector now uses 2×4 right-angle male header.

Version 1.4u

  • Added DS1307 RTC (real-time clock) and button cell battery (CR1220). Removed 24LC EEPROM.
  • Changed a couple of pin connections for the shift register and LCD. D3 is now connected directly to rain sensor (can be used for other purpose if not using rain sensor). Analog pins A2 and A3 are free; in addition, if not using RFM12B transceiver, digital pins D2 and D10 are free.
  • Added SMT (surface mount) variant 1.4s. All orders of assembled and tested product will receive 1.4s.

Version 1.3u

(Functionally the same as v1.2u. The main changes are in the extension board connector design and the additional analog pinouts).

  • Added shift register ~OE (output enable) line. More robust valve reset control during start-up. Extension board connectors are changed to 2×4 format.
  • TXD/RXD are now used as standard I/O pins. This frees up A2 and A3 analog pins. Thus TXD/RXD can no longer be used for serial communication. You can print to LCD for debugging purpose. If you do need serial communication, use software serial instead, or alternatively unplug the LCD and find the TXD/RXD pins on the LCD pin headers.
  • Removed indicator LED.

Version 1.2u

Changes from v1.1:

  • Added on-board USBtiny ISP programmer and USB connector (hence the name 1.2u). This allows OpenSprinkler to be programmer directly through USB without needing any external programmer.
  • Some components are replaced by more common parts, such as the switching regulator, the RJ45 connector, and the LCD. Some other components are removed, such as the power barrel, FTDI header, and reset button.
  • Added Rain Sensor terminal, as well as pin header for sensing power loss; also changed an LCD pin assignment to free up analog pin A1, which can be used to interface with external sensors.
  • Extension board connector is changed to a 2×3 pin format. There are now both an extension IN and an extension OUT connector, allowing cascading arbitrary number of extension boards.

Version 1.1

Changes from v1.0:

  • Station terminals are changed to common wire + individual station wire design. Added a 750mA fuse for current protectio, and RTC breakout pinouts for connecting external I2C RTC.
  • Support for arbitrary number (>8) of stations through extension boards. This is done by using shift register pinouts on the PCB. A connector links the master controller to extension boards, each expanding the stations by 8. The connector is wired as follows (master->extension): CLK->CLK, LATCH->LATCH, QH*->DATA, VCC->VCC, GND->GND. Additional boards can be cascaded by following the same connections.
  • The software (free for download in GitHub) is updated to support any number of ext. boards. Also added a self-test mode which can help quickly test all stations.

Version 1.0

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