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I’ve setup an OSPi + extender against a new Raspberry Pi 3. It seems like the quality of the wifi degrades when the zones are active, sometimes to the point where I can’t connect with a browser. My suspicion is that it’s either an issue of power quality (interference from the solenoids) or quantity (the additional load of running the valves, GPIO link, or even just processor working with those GPIO pins). Does anyone have any thoughts? I’m using the 500ma 24VAC adapter sold on this website. Would there maybe be value in grounding the board more directly?
Pi3 has a built in chip antenna. Power requirements are 5v @ 2.4A and it’s not as flexible as the earlier models.
I don’t know how much power the OSPi board provides the Pi but it’s probably not close to 2.4A.EMI from the power regulator under load could play a role in the decreased performance with the onboard antenna as well.
This is most likely a power-related issue I described here:
https://opensprinkler.com/forums/topic/ospi-only-works-when-connected-to-hdmi-output/#post-41925Because RPi 3 draws a considerable amount of current, it can cause the PTC fuse to drop higher voltage than previous versions of RPi. As a result, if your WiFi dongle is sensitive to the voltage drop, its performance will degrade. One option is to try a different WiFi dongle, another option is to solder a wire across the PTC fuse to bypass it. A third option is to power RPi 3 directly using a microUSB cable.
Obviously since OSPi was designed and manufactured before RPi 3 was released, these things could not be foreseen.
Ray et al.,
Thanks for the info. This may be a red-herring; since I’ve posted this I’ve noticed wifi drop-outs even when no zones are engaged.
That said, if I want to power the pi directly via that micro-usb, do I need to modify the OSPi to disable its 5v supply?
Doing a bit of research I ran across this describing the additional power requirements, especially regarding the built-in wifi. ( http://raspi.tv/2016/how-much-power-does-raspberry-pi3b-use-how-fast-is-it-compared-to-pi2b ). The description said that using the built-in wifi seemed to use 40mA idle and 100mA at peak. I’m not sure how that compares to the USB wifi dongles.
I’m running Ubuntu 15.10 on my pi. I don’t see anything especially relevant in my console log about the dropouts. I’m going to setup munin to log/graph wifi signal. My hope is that should let me figure out if this is genuinely correlated to the sprinkler timing or just periodic crappy signal.
Yeah, it definitely seems like it’s something power related. I’m seeing reboots as well, especially while the zones are active. Since both provide power, can I attach the micro-usb while the OSPi header board is connected?
Ok, issue at least partially and painfully solved. Reboots were power related, but it looks like my tests/program/setup were too much for the 500ma supply from the store. To test I was trying to run 4 zones + a master at the same time. Hooking the pi up via the micro-usb be was a mixed blessing. The pi stayed up during the whole test, but the valves shut after 30 or so minutes. It seems my valves (Rain-bird CP075s) pull 190ma each, and with five running it was just too much for the transformer. I’m assuming when the Pi was running off the OSPi power, the power would dip, it would reboot/freeze, the valves would close, and the transformer power would recover. With the Pi independently powered, it went until the transformer burnt itself out 🙁 .
I’ve ordered a more power transformer from the internet and will be more careful about running too many zones at once in the future. Its still not clear if the wifi issues were related to the OSPi or poor reception. I suspect in at least some cases I was mistaking the wifi issue for a reboot/freeze since there’s no display hooked to the Pi.
Thanks for the updates. Curious why you want to run a RPi3 instead of a model A or Pi2. I was lucky to find a Pi Zero and it’s been a flawless brain for the OSPi. I have it connected with a micro USB to Ethernet dongle from Amazon.
Turning on 4 zones + 1 master at the same time? Hmm, this is a lot of current. In that case, I would recommend you to power RPi separately using a 5V USB adapter and microUSB cable, while 24VAC will only need to provide current to the valves. If you do so, I recommend you to remove the PTC fuse (which looks like this: http://www.sellifuse.com/pptc/imges/2016_big.jpg) to avoid two regulated power sources competing with each other.
As I said in previous posts, I also think RPi Zero and A+ are the most suitable for OSPi as they are cheap, power efficient, and pretty sufficient to handle the computation need for OpenSprinkler firmware.
PTC removed. My OSPi v1.43+ didn’t have that specific chip. I followed the photos in Power pi and OsPi Separately. The 1.43+ didn’t have the 150 chip highlighted in the photos, but seemed to have two or three 050 chips stacked. I can confirm it seems to have had the desired effect and both Pi and all zones still work.
As for why I went with the rPi 3, I wanted wifi and figured onboard would be cheaper, easier, and better supported than a USB adapter. I may ultimately multi-task the pi into some other purposes as well.
I’m doing drip irrigation for vegetable gardens and put a valve in each of 10 beds. The valve per bed is almost certainly overkill in retrospect, but I didn’t want to dig up the yard twice and it seemed easier to have each bed connect to a single distribution pipe. I hadn’t appreciated the durations required for drip irrigating; if I want each bed watered during the morning hours its going to require having a few go at the same time.
I purchased a 60VA (2.5A @ 24VAC) supply from eBay but it was lost in the mail. The seller of the 60VA transformer from eBay also seems to have a store with the item listed. The documentation on that transformer lists the unloaded output as <= 30v. Despite their less than appealing name and poor quality picture, they’ve been pleasant enough to work work with and have sent a replacement for the one lost in the mail. After a week and a half of waiting for that, I got impatient and Amazon same-day’ed this Elk TRG2440 40VA to get my system up in the mean time. The voltage while unloaded on that ELK TRG2440 was 27v and seems to work well.
@jcodybaker: there is one batch of OSPi that came with 500mA PTC fuse, which is too small so we stacked another 500mA PTC fuse on top of. This is not really the correct approach to extend it to 1 amp, but OSPi was not designed to supply a huge amount of current to begin with, and we can hardly keep up with the ever growing power need of new versions of RPi…
Your point about built-in WiFi on RPi 3 is very true. I am actually curious how well the built-in WiFi works as I’ve heard mixed stories about its range.
The wifi is neither great nor awful. My Pi3 is not more than 30 feet from the wireless AP (an Apple 802.11ac AirPort Extreme), but if I were to draw a straight line it does go through a lot of old wood flooring and siding. The signal quality (iwconfig) in linux generally lists a quality of around 29/70. Since putting it on the independent power supply it seems to stay connected consistently and work well.
That 60 VA supply seems to work well.
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