Interfacing to another micro (Picaxe)….

[Anonymous]

Hi gang, I have the openspinkler board, will be installing it in the basement, where the sprinkler valve wires enter the house. I also have a Picaxe Microcomputer monitoring other aspects of my home water system, it’s located upstairs, this system includes the ability to record irrigation system flows. So I want the opensprinkler board to ‘tell’ the Picaxe when a particular sprinkler circuit has ben turned on. I have limited conectivity between the opensprinkler board and the picaxe – I have an I2C line (using an I2c bus extender, I have the chips to enable access to I2C from the Opensprinkler board location), I also have 4 spare cat5 wires between the locations (+ a ground wire). I will be using a total of 16 maximum sprinkler channels.

Note, I will program openspinkler to only allow one channel on at any one time, to simplfy operation of the system.

I am looking at 2 possible options for communication, as follows:

1. Modify the opensprinkler code to send out an I2C “Write” to the picaxe eeprom advising which channel is currently “ON”, if all off, send a “0”.

2. Install a second Picaxe micro at the opensprinkler location to ‘read’ the status of the valve lines, and send that info back to the main picaxe, either using the 4 lines (2^4 = 16 states), or doing an I2C “Write”. This probably requires some kind of opto-isolator/logic chip (16 of them) to translate 24 volts AC to a logic 1/0 at the picaxe, but eliminates the need to modify the opensprinkler firmware etc…..

Option 1 has the advantage that the picaxe has the ability to ‘talk’ to the opensprinkler, if, for eaxample, the irrigation water supply is low, and could slowly reduce watering volumes by modifying the ‘rainwater factor’ that’s already coded into the system.

I might need a hand with the firmware code modifications, I am a basic programmer, so C is a bit of a challange but it doesn’t look too complicated….

John

[Ray]

I am not familiar with Picaxe micro so I can’t comment on how easy or difficult it is to adapt OpenSprinkler firmware to it. Is there Arduino support for Picaxe? If so, it may be easy to adapt the code.

[Author]

Posts