Modular and Expandable Irrigation Controller
Described herein are several embodiments relating to modular irrigation controllers. In many implementations, the irrigation controllers are modular in that various functional components of the irrigation controller are implemented in removable modules that when inserted into position within the controller, expand the capabilities of the controller. Also described are various different types of expansion modules that may be coupled to the modular controller, having as variety of functions and features, as well as related methods of use and configuration of these modules in the controller. In some embodiments, a serial communication bus is provided between a control unit of a modular irrigation controller and an expansion module.
1 . A modular irrigation controller comprising:
a housing;
a control unit within the housing, the control unit including a first microcontroller for executing stored irrigation programs;
a plurality of expansion module mounting locations within the housing adapted to removably receive expansion modules;
a back plane circuit board comprising a bus coupling the first microcontroller to each of the plurality of expansion module mounting locations, wherein the bus comprises a serial multi-drop bus comprising a serial data line; and
an expansion module coupled to one of the plurality of expansion module mounting locations, the expansion module including a second microcontroller;
wherein the serial multi-drop bus supports and the first microcontroller and the second microcontroller are configured for bi-directional asynchronous communications between the first microcontroller and the second microcontroller.
2 . The modular irrigation controller of claim 1 wherein the serial data line consists of a serial data in line; and
wherein the serial multi-drop bus consists of the serial data in line and a serial data out line.
3 . The modular irrigation controller of claim 1 wherein the expansion module is configured to determine its connection to the one of the plurality of expansion module mounting locations.
4 . The modular irrigation controller of claim 1 wherein the second microcontroller is configured to initiate a message to the first microcontroller via the serial multi-drop bus.
5 . The modular irrigation controller of claim 1 wherein the bus supports communications using a universal synchronous asynchronous receiver transmitter (USART) protocol.
6 . The modular irrigation controller of claim 1 wherein the bus supports a 9-bit communication protocol.
7 . The modular irrigation controller of claim 1 wherein the bus supports communications at frequencies between 200 and 400 MHz.
8 . The modular irrigation controller of claim 1 wherein the expansion module comprises:
driver circuitry within a module housing of the expansion module, the driver circuitry coupled to the second microcontroller; and
an output connector coupled to the driver circuitry, the output connector adapted to be electrically coupled to at least one irrigation valve.
9 . A method for use with a modular irrigation controller comprising:
removably coupling an expansion module to one of a plurality of expansion module mounting locations within a housing of the modular irrigation controller, the modular irrigation controller comprising a control unit including a first microcontroller, the expansion module comprising a second microcontroller, each of the plurality of expansion module mounting locations electrically coupled to the control unit via a bus, wherein the bus comprises a serial multi-drop bus comprising a serial data line; and
asynchronously communicating bi-directionally between the first microprocessor and the second microprocessor via the serial multi-drop bus.
10 . The method of claim 9 wherein the serial data line consists of a serial data line; and
wherein the serial multi-drop bus consists of the serial data in line and a serial data out line.
11 . The method of claim 9 further comprising:
determining, by the second microcontroller of the expansion module, a connection of the expansion module to the one of the plurality of expansion module mounting locations.
12 . The method of claim 9 wherein the asynchronously communicating step further comprises initiating a message from the second microcontroller to the first microcontroller via the serial multi-drop bus.
13 . The method of claim 9 wherein the asynchronously communicating step comprises asynchronously communicating via the serial multi-drop bus using a universal synchronous asynchronous receiver transmitter (USART) communications protocol.
14 . The method of claim 9 wherein the expansion module comprises:
driver circuitry within a module housing of the expansion module, the driver circuitry coupled to the second microcontroller; and
an output connector coupled to the driver circuitry, the output connector adapted to be electrically coupled to at least one irrigation valve.