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Ray;
I would like to reach some additional zones about 60′ way from the controller. I was considering using the Zone extender and making a custom cable between the main unit and the Zone extender. How far can I run the cable between the main unit and the zone extender?
background.
Ultimately I would like to drive three or four linear actuators. I would H-bridge them in the standard way and have the open sprinkler logic treat the bridge as valves.that way I only need two zones for each actuator. my problem is I already have a standard garden relay 7 wire cable in place, and am trying to avoid pulling a new underground wire. placing the zone extender on the other side of the cable from the main unit is an attractive idea, but I am not clear what signals you are running on that ribbon cable?.
60′ is probably ok. You can make a custom cable using a long Ethernet cable. We don’t have any test data on how far the cable can run — this depends a lot on for example, the wire thickness. So I can’t say for sure, but I think 60′ sounds ok.
The signals running on the ribbon cable are I2C (if you are referring to OS3) and shift register (basically SPI bitbang) data for OS 2.x or OSPi. These are not direct on/off signals.
Ray – What are the pinouts for the DC zone expansion 3.0 board.. I see that you are using a 10 pin connector, and the diagrams on Github are for 2.0 with a 8 pin connector. I am going to try and get it to run over a remote cable but I only have a 7 wire cable in place.. that should work., since AFAIK I only need to run the GND, VCC, DAT,CLK,LAT,NOE – did I miss something?
thx
On the DC controller and expander, only 6 (in fact, technically only 5) wires are used out of the 10-pin cable. The Eagle design files of all versions are in github, maybe you were looking at the wrong github, but the correct link is here:
https://github.com/OpenSprinkler/OpenSprinkler-Hardware/tree/master/OS/3.0/DC_driver
I’ve attached two images showing the 10-pin connector on the controller, and also on the expander, so you can figure out exactly which pins are used, and the ordering of pins. When I say ‘technically 5’ I mean the DCG (DC ground return) occupies 2 of the pins, so technically if you are short of wires you can just use either one of them.Please note that in contract to expander 2.x, expander 3.0 uses I2C, so there is no DAT, CLK, LAT, NOE etc., instead, it has SDA, SCL.
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Did you ever make this long range extension cable? I moved into a new home with MUCH more property, and as such, currently has two separate irrigation timers (8 channels on each), that are located about 75′ from each other. I want to replace them with my OSpi and an Expansion board, if the SPI is slow enough to not have noise issues. Otherwise, I’ll need to buy an additional opensprinkler unit, which would be quite a bit more expensive.
The alternative is, of course, just extend the 24VAC lines for the valves to the OSpi’s location, and install the expandion board there.
60′ with i2c or spi or any 3.3V logic signals is a horrible idea IMHO and not likely to work at all at least not reliably. From my quick checking “long” for i2c is something like 10′ and that is with buffering. Some sort of differential scheme would be a big improvement and probably possible. Something like RS485 for example. The other issue is electrical storm transients – again something like RS485 is much better.
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