Assistance with sourcing accessories for GrovePi project


#1

Hello,

I’ve just discovered GrovePi and I’m very interested in using this for a little home project. I’m hoping this community can point me in the right direction.

Our idea is to use a Raspberry Pi 3 to monitor our boat for 3 events:

  1. Water in the boat (is over the floor and therefore perhaps sinking as it sits in our boathouse)
  2. Is there power being delivered from the outlet to charge our battery (we leave our battery on trickle charge but want to make sure the outlet the charger is plugged into is working and hasn’t tripped)
  3. Being able to deliver results of the above two monitors via SIM card. I’m still working out if we’ll be able to have Internet to the boathouse. Ideally this would be best as then the Pi3 could use it’s wifi.

We’re very early in thinking about doing this project. I’ve heard about GrovePi while reading the Pi Forums and thought this would be a great product for us to use for our little project. But I’m now in the stage of seeing if the various connections we need are available for the GrovePi.

I really like how the GrovePi allows us to easily add the hat to the Pi3 and add as many connections as we need. I suppose our 2 connections means we don’t need to have the full 15 like the GrovePi has but I haven’t seen any other hats with connections like the GrovePi with less ports.

As I begin thinking about this project a number of questions come to mind:

  1. Is there a case available for the Pi3/GrovePi that will be waterproof but has sealed ports for the various monitors to connect outside this case? In our case we’ll have two monitors. I see cases on the dexter website but none are waterproof.
  2. I see there is a Grove water sensor - Model: SEN113104. If we put this near the bottom wall of the inside of the boat, how wet can this sensor get? Is it only the bottom (breadboard) part? What if the wires or the connector the wire fits into on this sensor. I’m thinking of a drastic scenario where the boat filled up fast…will the sensor not work if the entire sensor and cable was submerged in water? Ideally I think a one wire water sensor would be ideal but all I can find on the dexter site is a one wire temperature sensor. Or adafruit has a one wire water sensor - DS18B20 but it doesn’t have the end on it to connect to a GrovePi.
  3. In finding a sensor that will tell me if my charger is not getting power from the nearby outlet…my thought is to use a battery backup type system on the Pi and have it also plugged into mains power. If mains power is lost, the battery backup kicks in and an alert is generated that mains power is lost. I see lots of battery type systems on dexter webiste related to robots. Is there a battery backup available to what I need that will work with the GrovePi attached as well?

Like I said, I’m at the very early (shooting around ideas) stage of this fun little project. Any pointers or ideas you can give me would be greatly appreciated by my kids and I.

Thank you.


#2

That really sounds like a great project and you should be able to use the GrovePi for it.

  • You should be able to use the water sensor http://www.seeedstudio.com/Grove-Water-Sensor-p-748.html, but it might be worth covering the non exposed side with electrical tape so that the water does not short anything on the board. There is not a lot of current on those lines but it might be better to not short anything on the board. The DS18B20 seems like a temperature sensor
  • Grove lineup has an electricity sensor: http://www.seeedstudio.com/Grove-Electricity-Sensor-p-777.html but this monitors flow of current, rather than if the current is on/off. If you want to just detect if the socket is working, one of the things that you can do is to take a small usb charger like this https://www.amazon.com/Omni-Universal-Adapter-Charger-Samsung/dp/B00YHZI0EC/ref=sr_1_10?ie=UTF8&qid=1470898449&sr=8-10&keywords=usb+charger and use a USB cable to feed it to a breakout board like this: https://www.adafruit.com/product/1833 and then with a cable like this http://www.seeedstudio.com/depot/grove-4-pin-to-grove-4-pin-converter-cable-5-pcs-pack-p-1195.html?cPath=178_179 feed it to the GrovePi. The grovePi can monitor the voltage on that pin and if it reads 5V, then the socket is working, if not then the socket is not working.
  • The Raspberry Pi is pretty much a fully functional computer, so for a mobile connection, you can just use a USB adapter like this https://www.amazon.com/Huawei-E1750-USB-3g-Dongle/dp/B00381NBI6/ref=sr_1_1?ie=UTF8&qid=1470897953&sr=8-1&keywords=E1750. There is a list of adapters here that the Pi supports: http://elinux.org/RPi_VerifiedPeripherals#USB_3G_Dongles
  • If you are interested in a smaller variant of the GrovePi+, we have the GrovePi0 which just finished it's kickstarter: https://www.kickstarter.com/projects/john-cole/grovepi-zero-effortless-internet-of-things-devices/description. It is fully compatible with the GrovePi and should be available in a month or so
  • We have an easy to use OS for the Pi too here: https://www.google.com/#q=raspbain+for+robots and have a variant which broadcasts it's own wifi hotspot which would make it easier to connect when you don;t have reliable wifi: http://www.dexterindustries.com/topic/new-operating-system-raspbian-for-robots-cinch/
  • We have seen people using normal waterproof enclosures, something like https://www.amazon.com/Estone-Waterproof-Plastic-Electronic-Enclosure/dp/B00JEWNKR0 and this https://www.amazon.com/White-Waterproof-EnClosure-Junction-200mmx155mmx80mm/dp/B00QC301V2/ref=pd_sim_60_6?ie=UTF8&dpID=31EdnaOvLTL&dpSrc=sims&preST=_AC_UL160_SR160%2C160_&psc=1&refRID=V6YPH4WFKAVP5P0BJAZB and then use waterproof joints https://www.amazon.com/3-6-5mm-Cables-Waterproof-Plastic-Glands/dp/B0079G1HG4/ref=pd_sim_60_3?ie=UTF8&dpID=31xAAEdEoHL&dpSrc=sims&preST=_AC_UL160_SR160%2C160_&psc=1&refRID=GA1RP4ANG26ETAEW8CAQ to take the cabling out, so you should be able to use those.
  • The bigger batteries that we sell are for the robots and you shouldn't need those. The grovePi and everything else for your project should run at 5V, so you can use a battery pack like this https://www.amazon.com/Anker-PowerCore-Ultra-Compact-Fast-Charging-Technology/dp/B01CU1EC6Y/ref=sr_1_6?ie=UTF8&qid=1470899126&sr=8-6&keywords=battery+pack+anker and in this case, you can even use that 5V charger to charge this battery and feed to the GrovePi to monitor the power on socket too.
  • You can also add other sensors if you want: http://www.seeedstudio.com/wiki/Grove_System and maybe set up a vizualiztion up on the web for them too with initial-state: https://www.initialstate.com/ We have an example up here: https://github.com/InitialState/grovepi/wiki
Do let us know if you need any more information and I hope you have a great time building your project.

-Karan


#3

Hello Karan,

Thank you very much for this detailed answer. Very much appreciated! Lots of useful links to help us get started.

Regarding the water monitors…would you know why these type of monitors - http://www.seeedstudio.com/Grove-Water-Sensor-p-748.html, seeing as they deal with water, are not covered more to handle getting wet so shorting out won’t be an issue? I’ve found other types of water sensors:

https://www.cooking-hacks.com/liquid-presence-sensor
https://www.cooking-hacks.com/watermark-soil-moisture-sensor-4-5m

These both look like they would be perfect for my use. The watermark-soil sensor even has various lengths available. Would Dexter Industries have instructions on how to cut the end off of one of these sensors so that I may add them to the GrovePi board?

Do you sell various lengths of the sensor cables? The pictures I see show them as being very short. If my Raspberry Pi is a few meters away from the device being monitored…how do I extend the sensor cable to reach?

Thank you again for your advice with our project.


#4

I think the grove water monitor does not come with the whole sensor covered because it expects the water level to be in that small portion only and is not designed to be immersed. The moisture sensor from cooking hacks might not be the best thing becasue those sensors are also not built to be immersed. The other liquid presence sensor looks pretty good for detecting the presence of water. For connecting the liquid presence sensor, you can connect the red wire to tge red wire on the grove cable and grey wire to the white wire on the grove cable.

For the cables, it might be best to use a cable from here: https://www.seeedstudio.com/item_list.html?keywords=grove%20cable which breaks the cable on one side to a female breakout which can be used to easily connect the liquid sensor. There’s also a 50cm cable in there if you want longer cable. If you want an even longer cable then you’ll have to cut two cables and join them.