We've been experimenting more and more with tablet ground stations here at Event 38 and have had a lot of success using the DroidPlanner app. The software has been working well for us but we found our ground station setup was really cluttered, the opposite of what we were going for when switching to tablets. My main complaint was having the ground side telemetry radio dangling from my phone or tablet. Not only was it a hassle and prone to coming unplugged, it was also hard to keep it in a good position for radio reception.
Following Arthur Benemann's instructions, we set up a bluetooth bridge that would let us at least set the radio down and move freely with the ground station tablet. A huge improvement, no doubt, but still a little rough around the edges, even needing power from a laptop. So we added a nice case and a single cell LiPo battery to power it all. This worked even better, and looked pretty nice as well!
It still had some power management issues but it worked well enough for our purposes. At this point we're thinking about running a Kickstarter campaign to run a production scale build of these but we'd like to get some feedback from potential users before we solidify the specs. I'd appreciate any/all comments on what kind of features you'd like to see on something like this, if any, besides the telemetry bridge to Bluetooth. Right now we're planning on including the following:
- Internal LiPo battery, rechargeable by USB
- Battery status LEDs
- 433 and 915MHz variants to be compatible with any 3DR Radio
- ~20m Bluetooth range
- ~1km telemetry range
- 5-6 hours battery life
- A durable plastic enclosure
Is there anything else we should consider adding to improve the functionality or usability? Do you think this would be priced fairly at $139? Let us know what you think!
I would be interested in one, but I would be a lot more interested in one if you could add a WiFi shield and use it as a router that can support multiple connections... I would love to be able to either UDP or TCP out to multiple computers without having to either create a custom mesh network off of my laptop or hook up a router. I was thinking about making such a device using a Pi, but you have a much better start!
@R_Lefebvre The first bluetooth 4.0 breakout boards were not UART interfaces they are SPI but I just saw this
http://redbearlab.com/blemini/ It could work without the Arduino buffer. Should be pin compatible with this design.
@Jeff check out this bluetooth module. It should be pin compatible with your design so if the module can be swapped with this one iOS support could be added at a later date. There is an open source iOS ground station app already going I might volunteer myself to add support for this.
Why do you need to use an Arduino as a serial buffer? Can't simply set the Bluetooth baud at 57k, and then Tx-Rx Rx-Tx the two modules, and that's it?
Anybody know if it's possible to get Mission Planner to make a bluetooth connection? My laptop has a bluetooth module of course. It would be super convenient to simply bring one device, and be able to use tablet or laptop with it.
Thanks for all the comments and suggestions, everyone!
We are including a real battery charging circuit which will turn off once the LiPo is full, so no worries about that. We found that for these small batteries, there just isn't much difference in cost between NiMH and LiPo cost.
It will be compatible with RFD900, just as the normal 3DR 915 radios are, but obviously will not have the same range. I've found that using an RFD900 radio on the ground paired with a 3DR in the air gets you up to 3.5-4.5km range.. not sure what range it would be in the reverse configuration.
We'll definitely add iOS support if/when there's ever the ability to run any apps on iOS that work with APM!
I'd recommend going with a Bluetooth LE module to support iOS but I understand it has really limited support on android right now so not really feasible. Also I think you would need an microprocessor between the radios if going with a bluetooth LE connection.
R_Lefebvre they only required the hardware approval with the older bluetooth SPP profile devices. The newer bluetooth 4.0 LE chips work without any hardware approval or anything like that. This is how DJI is connected their data modem to iOS devices. Check out http://www.makershed.com/Bluetooth_Low_Energy_BLE_Shield_for_Arduin... this is possible because the app itself is all that needs approval not the hardware its wirelessly connecting to.
Greg, maybe not. Apple have actually covered that option as well. An iDevice will not link to a Bluetooth module which has not paid the AppleTax, and most of these cheap Bluetooth serial devices have not paid the tax. So it would likely take a custom made Bluetooth serial device to enable you to connect to an iDevice.
So with a little work we will be able to use an Ipad as a part of ground station?
This a good idea and I probably would have purchsed previously. I have added a 3dr Radio and bluetooth module to my 9x transmitter. Saves having to carry round another box/battery. The telemetry powers on when I switch on the transmitter.
It's a cool project, I'm happy that people are using the Bluetooth functionality.