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Aug 17, 2015, 01:43 AM
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Mini-HowTo

DIY sensors for FrSky Telemetry


I made a few sensors, all based on Arduino Pro Mini like this one. They are based on the multi sensor that I started a thread on earlier: https://www.rcgroups.com/forums/show....php?t=2394886
They are compatible with both X- and D-series receivers from FrSky. Since these Arduinos are 5V, and the telemetry ports on the receivers operate at 3.3V, the output pin is connected through a 5.6 kOhm resistor. The 3-pin headers are soldered to the GND, A6 and A7 pads, located at one of the short edges of the board. A wire from A6 to Vcc supplies input voltage to the Arduino, and the 5.6k resistor connects A7 to output pin (D12).
If using anything else than 5V on the RX side, a different wiring is needed, using RAW pin for voltage input.


Fred
Last edited by flarssen; Aug 26, 2015 at 11:40 AM. Reason: Added warning regarding powersupply
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Aug 17, 2015, 01:43 AM
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GPS

For this one, I used an UBLOX VK16U6 module, bought for less than $10. The 4-pin header and the two additional wires were added to bring out I2C for future expansion, and are not needed for GPS only. Currently the code will output telemetry data at the same rate as it receives data from the GPS unit. I configured it to 3Hz, and this seems to work OK with the Taranis. Haven't yet tried with additional sensors. I also configured the GPS unit to only output GPRMC and GPGGA sentences, as that is all that is needed.

16,10,2015:
Added code for GPS+IMU, connected to I2C pins.
Last edited by flarssen; Jan 04, 2016 at 04:11 PM.
Aug 17, 2015, 01:44 AM
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Vario

I have ordered a few IMU's from EBay, with HMC5883L/MPU6050/MS5611 chips.
Total cost is in the same range as for the GPS in the previous post.
Boards are mounted back to back with foam tape in between. Lengthwise, the IMU is positioned so that the I2C pads overlap. They are connected with jumper wires that are slightly bent to allow the two boards to line up in the other direction.
Both PCB's are pretty thick, so overall weight is a bit higher than the FrSky one, about 4.85g, but this one will also report G-force (currently only D-series protocol). I will make another one using a different Mini Pro that is 0.9g lighter, and leave out the second pin header.
Make sure not to seal the two holes of the baro chip, if heat shrink is used. It should also be protected from direct light.

The code with acceleration also needs MPU605X library.
Last edited by flarssen; Jan 04, 2016 at 03:35 PM.
Aug 17, 2015, 11:25 AM
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Very interested I am.

So, if one is looking to start programming with an Arduino chip, is there a good "how to get started tutorial" you can recommend? I'm a software developer nearing retirement and this looks like a great pastime for those no-fly cold winters in Northern Minnesota that will be coming all too soon.

Stu Olson
(yes, my relatives immigrated from Norway)
Last edited by arizona98tj; Aug 17, 2015 at 11:51 AM.
Aug 17, 2015, 11:50 AM
Seattle, WA
Also interested.
Will have to get the parts ordered and give it a go.
Thanks
Aug 17, 2015, 01:28 PM
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Quote:
Originally Posted by arizona98tj
So, if one is looking to start programming with an Arduino chip, is there a good "how to get started tutorial" you can recommend?
Just go to https://www.arduino.cc/. There is a getting started section there, and download links for the development tool. You must download and add the two libraries linked to in the source file. The TinyGPS link seems to be broken, but should be easy to find with Google.
You will need an USB->serial TTL adapter like this one or similar, as the pro mini have no USB port. I don't solder any pins to the board, I just insert the pins and tilt them a bit so that they make contact during the upload process.

Fred
Aug 17, 2015, 06:55 PM
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Thank you very much for the link. I look forward to giving this a try. I'll probably order the parts now and with any luck, they won't get lost during the move. Once settled in early next year, I can get my work room set up and give it a try.

Much appreciated!
Aug 17, 2015, 09:34 PM
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Hello i like the looks for this one
Do you think it work on a Arduino Nano V3.0 - ATmega328 i have some lying around and gps with a compass to
any way i will give it a go tonight

Thanks
Aug 17, 2015, 11:22 PM
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Quote:
Originally Posted by yak-54
Hello i like the looks for this one
Do you think it work on a Arduino Nano V3.0 - ATmega328 i have some lying around and gps with a compass to
any way i will give it a go tonight

Thanks
Sure, I used a Nano during development (USB makes it easier to upload sketch). I choose Pro Mini for the final version because of price, size, weight, etc.

Fred
Aug 18, 2015, 01:29 AM
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Quote:
Originally Posted by flarssen
Sure, I used a Nano during development (USB makes it easier to upload sketch). I choose Pro Mini for the final version because of price, size, weight, etc.

Fred
is any change i need to do to the sketch


Thanks
Aug 18, 2015, 01:48 AM
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Quote:
Originally Posted by yak-54
is any change i need to do to the sketch


Thanks
Regarding board type? No. Just change the baudrate (last line of Setup()) to whatever your GPS uses. Serial pins and USB share the same serial port, so only connect one at a time.

Fred
Aug 18, 2015, 02:44 PM
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frater's Avatar
I have no experience with Arduino besides my recently acquired 3D-printer.
Could this thing become some kind of all-in-one sensor by adding a G-sensor a barometer and maybe also a current sensor?

Are you feeding the Arduino a seperate 5V?
Would a stepup work and feed the whole thing from the S-port?
Aug 18, 2015, 04:29 PM
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Quote:
Originally Posted by frater
I have no experience with Arduino besides my recently acquired 3D-printer.
Could this thing become some kind of all-in-one sensor by adding a G-sensor a barometer and maybe also a current sensor?

Are you feeding the Arduino a seperate 5V?
Would a stepup work and feed the whole thing from the S-port?
I didn't check to see if they were still on sale, but check out this thread
https://www.rcgroups.com/forums/show....php?t=2394886

Edit Still on sale cheap
http://www.allerc.com/hyperion-parts...17.html?page=0
Aug 19, 2015, 12:10 AM
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Quote:
Originally Posted by frater
Could this thing become some kind of all-in-one sensor by adding a G-sensor a barometer and maybe also a current sensor?

Are you feeding the Arduino a seperate 5V?
Would a stepup work and feed the whole thing from the S-port?
That's the reason for adding the I2C pins; I plan to connect an IMU to add vario and accelerometer data. The rest I leave to the sensor in the thread Dean linked to above. I'm experimenting with reading D-series data on that one, and let it bypass it to the Rx. So far I get some data corruption, leading to "sensor overflow" with OpenTx 2.1. If I can get it to work, I can plug GPS and/or vario into it, and have all data available in Taranis. Arduino pro mini is very basic with just one serial port. For S-port, it's just a matter of joining them together.

The Arduino and GPS is powered from either Sport or the servo bus on D-series RX, so 5V will be max and a step up is probably needed if operating on a single Lipo cell.

Fred
Aug 19, 2015, 07:15 AM
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Quote:
Originally Posted by flarssen
Regarding board type? No. Just change the baudrate (last line of Setup()) to whatever your GPS uses. Serial pins and USB share the same serial port, so only connect one at a time.

Fred
try to upload the sketch getting some errors

FrSkyGps.ino: In function 'void setup()':
FrSkyGps:156: error: 'SOFT_SERIAL_PIN_12' is not a member of 'FrSkySportSingleWireSerial'


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