XR8 rx telemetary sensors

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ShowMaster
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Re: XR8 rx telemetary sensors

Post by ShowMaster »

Can you post some typical eBay links for these parts please or full part numbers? I assume these are SMD size?
1 - mcp1703 3v3 LDO
1 - Atmel ATTiny13
I'm going want to make your design if a board becomes available. I've ordered parts to construct Mikes design already.
Thank you.

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Re: XR8 rx telemetary sensors

Post by MikeB »

rdeanchurch wrote:So just to be sure, Mike...The download you put on today is For the AtTiny85 and the one in post OF 20Oct was for the AtTiny13.
The download of the 21st is also compiled with the AtTiny13 selected so I could test it. It won't run unchanged on the '85 due to the different clock speed. I included the makefile, and it is supposed to compile with a command line:
make CPU=85
to produce the hex for the '85.

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Re: XR8 rx telemetary sensors

Post by MikeB »

aadamson wrote:NOTE: I can bring out the pin 3 debugging signal to a test pad if that helps or a small via?
Can I assume this with the right voltage divider external to this board, if connected on the lipo side would sense lipo power and provide it via telemetry?
Worth bringing the pin 3 signal out, makes it easy to get to (might even by worth bringing pin 2 to a small pad, we might find a use for it in the future!).

Yes, with the right voltage divider it will sense the lipo voltage and it will appear as A2.

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Re: XR8 rx telemetary sensors

Post by MikeB »

Updated zip file with Sport85.hex (for the 'tiny85) included. This is untested, but the timings should be adjusted for the lower clock speed.
sportTinyAnalogPC.zip
(9.81 KiB) Downloaded 354 times
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Re: XR8 rx telemetary sensors

Post by aadamson »

MikeB wrote:
aadamson wrote:NOTE: I can bring out the pin 3 debugging signal to a test pad if that helps or a small via?
Can I assume this with the right voltage divider external to this board, if connected on the lipo side would sense lipo power and provide it via telemetry?
Worth bringing the pin 3 signal out, makes it easy to get to (might even by worth bringing pin 2 to a small pad, we might find a use for it in the future!).

Yes, with the right voltage divider it will sense the lipo voltage and it will appear as A2.

Mike.

Thanks Mike,

True to form, overnight I thought about it... it would be pretty easy to move the tiny to the back side of the board (still easily solderable if you have build it). This would cut the board size in half. I might be able to add a small prototype area where you could solder in the resistors *or jumpers* for the voltage divider etc.

I'll also re-think those other pins and see if I can't figure out a more elegant solution for them.... maybe just an inline connection instead of scattered all over the board make sense, part for icsp and part for debug...

Alan

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Re: XR8 rx telemetary sensors

Post by aadamson »

ShowMaster wrote:Can you post some typical eBay links for these parts please or full part numbers? I assume these are SMD size?
1 - mcp1703 3v3 LDO
1 - Atmel ATTiny13
I'm going want to make your design if a board becomes available. I've ordered parts to construct Mikes design already.
Thank you.
Can't help much for ebay parts I usually don't get them there.

The processor is this exact one from digikey - ATTINY13V-10SSURCT-ND
The mcp1703 is this one from digikey - MCP1703T-3302E/CBCT-ND
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Re: XR8 rx telemetary sensors

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I understand that even small boards in small runs can be very expensive for an individual to finance.
If so and one would want to etch their own board, wouldn't the single sided board be the best choice?
I'm not sure what the minimum 1 or 2 sided board run is so maybe someone can post the total cost per board and we can see how many would commit the $ on Paypal to have blank boards made.
That or some DIY instructions on the best and easiest way to make our own. I'm familiar with the etching price due but not how to transfer the artwork to the board. I've seen where transferring laser printed artwork with a hot iron is one way? Not owning a laser printer I guess I'd have a Staples store make the laser copies I need?
I'm up trying it with some prep help posted.

Curse Frsky for putting us in the situation!
Praise those that want to help us out of it!
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Re: XR8 rx telemetary sensors

Post by MikeB »

aadamson wrote:I'll also re-think those other pins and see if I can't figure out a more elegant solution for them.... maybe just an inline connection instead of scattered all over the board make sense, part for icsp and part for debug.
The ideal would be the 6 pads/pins for the programming in a line or in a 3x2 array:
1. MISO
2. VCC
3. SCK
4. MOSI
5. RST
6. GND

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Re: XR8 rx telemetary sensors

Post by aadamson »

MikeB wrote:
aadamson wrote:I'll also re-think those other pins and see if I can't figure out a more elegant solution for them.... maybe just an inline connection instead of scattered all over the board make sense, part for icsp and part for debug.
The ideal would be the 6 pads/pins for the programming in a line or in a 3x2 array:
1. MISO
2. VCC
3. SCK
4. MOSI
5. RST
6. GND

Mike.
yeah, the typical icsp programming header.... it's just board space :)

I'll look at some options.
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Re: XR8 rx telemetary sensors

Post by aadamson »

ShowMaster wrote:I understand that even small boards in small runs can be very expensive for an individual to finance.
If so and one would want to etch their own board, wouldn't the single sided board be the best choice?
I'm not sure what the minimum 1 or 2 sided board run is so maybe someone can post the total cost per board and we can see how many would commit the $ on Paypal to have blank boards made.
That or some DIY instructions on the best and easiest way to make our own. I'm familiar with the etching price due but not how to transfer the artwork to the board. I've seen where transferring laser printed artwork with a hot iron is one way? Not owning a laser printer I guess I'd have a Staples store make the laser copies I need?
I'm up trying it with some prep help posted.

Curse Frsky for putting us in the situation!
Praise those that want to help us out of it!
Boards like this are actually very inexpensive... OSHPARK.com is your friend here :)... Just off the top of my head as I'm doing something similar for 30v in 12v out on a small switcher to power LED's and Gimbal with 6-4s down to 12v, that board is $5.00 for 3 including shipping... Excellent boards and excellent service...

Here's one I did a while back... A full STM32 F3 (hardware floating point on a M4 core, 256k flash, 40k ram) - Pin, feature, function compatible with an arduino pro mini :)...

Image

And here's a 3 axis gimbal controller that I'm spearheading at the moment... all done on OSHPark boards. And baked in a toaster oven with an arduino reflow oven controller :)
Image

The F3 Mini was about $5.00 for 3 boards and the gimbal controller is $19.00 for 3 boards, they charge by the square inch rounded up but will do double sided, slikscreen, solder mask, etc and you can order more than 3 if you want... it's prefect for small run stuff... if you want more, then it's cheaper per board to go to china and there are places there where you buy a sheet and they fit as many of whatever your design is as will fit... those aren't too expensive either, but it drives the board cost down to in the sub $1.00 range for something like this...

So let's take a step back and talk size... what is a reasonable board size here? Anyone have a preference?
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Re: XR8 rx telemetary sensors

Post by ShowMaster »

Probably the size should be just large enough for ease of soldering for most. From the 603 size parts you referenced to, I wouldn't want to go any smaller. If that's agreed on then that would limit board size I'm guessing.
If a forum member was to build and sell these ready to go that's then would decide the size.
We know Frsky will get theirs on the market maybe this year yet but at what cost and will it be a system a alone or bundled with a higher priced sensor? Many are just looking to have the A2 option again like the D series receiver, nothing more for most planes. Unless Frsky redesigns the X8R to offer this I'm thinking Mikes design will be a very popular option.
I have 2 X8R receivers I'm not using because if the missing A2 option I've come to depend on. Such a waste!
If this boards final design works out maybe the board company mentioned would setup a part number and we could just individually order boards using it and they would have the master layout on file. That way we each pay for our own boards without having to supply the layout files each time.
So to answer your question with a question.
Is this a DIY project for the assets or a board for a person that has the skills to solder the smallest of parts?
I'm game to try both. Personally I just need help with a parts source for the size decided on.
I'm good for 3-4 boards. 2 I need, 1 or 2 to practice on ha ha.
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Re: XR8 rx telemetary sensors

Post by aadamson »

Well, not that I need another project, but.... (don't you love those answers)... I too miss just having lipo voltage in telemetry. I'm a rather newbie when it comes to opentx and taranis in my case. But the board side I'm pretty familar with. one sided and I can stick everything in an oven and reflow it all at the same time.

I'd be willing to do a panel of boards and get a stencil and go a panel at a time. I have no idea what the price would be, I'd need to look at a BOM, etc...

I think I just answered my own question... let's stick to one sided, make programming, debugging the board easy and get to a first rev and go from there.

I would expect that I can get a panel of oh, maybe 10 or 20 board, let's say 10, then get them done at OSHpark for now, that would give us 30 boards and I could probably build that many pretty easily too....

Like I said, not that I need another project :)... but it has an immediate need... I'm going to add a small proto area so you could use through hole resistors to create the voltage divider for whatever you wanted to sample.... :)...

Alan
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Re: XR8 rx telemetary sensors

Post by ShowMaster »

I'm in for some boards Alan. I need 3 since a good friend just got his Taranis.
If you can figure out a price and shipping to Los Angeles I'll advance the money with Paypal to get your seed money going.
If it's a bust but we agree on the price I'll risk it!
I'm all for progress in our hobby.
So boards or ready to use, your call.
I was looking into ordering some of the parts for the SMD version to have them but you'll have better buying prices if you buy them in quantity.

I have the larger parts heading this way from eBay to hand build Mikes layout. Smaller would be better later.
Maybe a test run just in case Frsky actually releases something this year yet. Murphy's law!
Count me in what ever you decide and a Paypal account.
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Re: XR8 rx telemetary sensors

Post by aadamson »

I'll keep you all posted... working on new board layout with iscp header, etc... I have it in *really* large size right now, just need to think through how best to make smaller :)...

Alan
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Re: XR8 rx telemetary sensors

Post by aadamson »

Ok, new version, a tad bit larger... BUT

- includes the AVR programming port ISP
- includes 2 1/6w resistors for voltage divider
- includes 2 spare pins broken out
- is single sided

You'll see the dimensions in the picture, those are in mm's.

I'll gen up some gerbers and see what the price per board will be and I'll take a look at a BOM... I think I use most all those parts so I should be able to throw together a BOM on sandsquid or digikey easy enough...

I still need to clean up some labels etc, but this is looking pretty good... that ISP header is as big as the tiny :)...

Image
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Re: XR8 rx telemetary sensors

Post by MikeB »

Single sided? I think I can see two tracks on the blue side! (Pins 1 and 5 of the ICSP header) not to mention some vias connection the grounds together.

Nice work though.

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Re: XR8 rx telemetary sensors

Post by aadamson »

single sided to me means (all parts on one side)... it's 2 layers, but single sided :)...
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Re: XR8 rx telemetary sensors

Post by aadamson »

Ok, here is what will be 20131022-1 rev of this board.

Image

Eagle files are here

https://github.com/akadamson/X8R-Analog-Sensor

OSHPARK pricing on this board is $2.60 for 3 boards or .87 (87 cents) each! :)...

I'll go work on the BOM next and post those numbers...

I'm thinking we'll be well south of $5.00 each on these! May be around $3.00

UPDATE:
Here is the online BOM, this will shop this around a number of vendors and you can tell it how aggressive you want the shopping to be...
http://www.sandsquid.com/#vOGoWR

QTY 1 from digikey is a bom of $3.24

So bottom line.

Board is 0.87
BOM is 3.24

So total minus S&H just for parts is 4.11... ok, south of $5, and I know if you went to qty 50 that the parts comes down to around $2 :)...

This doesn't include any resistors for the voltage divider, but those will be pretty cheap... probably pennies

I guess I'll get some board ordered... I might move this design to Diptrace so that I can panelize it something like a 2x5 panel or some should would be really easy to build and I'd get a stencil from oshstencil.com and built 10 at a time if there were enough interest...

So I guess spread the word, let's see who's interested.

Alan
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Re: XR8 rx telemetary sensors

Post by aadamson »

Mike, how much do you know about the s.port protocol... What if we put pads on the top and bottom of the board instead of holes, and mounted a 2x3 header to them. It looks like the protocol supports some form of handshake on the bus. Could devices be daisy chained? I know just a single one of these, but say you have the vario, or lets say we decided to do a current version of the same? with 2 headers, you could daisy chain devices?

Just thinking outloud, but a curious thought... I know nothing about the protocol in use...

Alan
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Re: XR8 rx telemetary sensors

Post by Imho »

Great work! I know you've made the Eagle files available to everyone but I wanted to check that it's OK to use them and supply those in Australia who are interested (at cost + shipping, as a community service)? Somewhere like ITEAD will do 10 boards for $10 + shipping.
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Re: XR8 rx telemetary sensors

Post by aadamson »

Imho wrote:Great work! I know you've made the Eagle files available to everyone but I wanted to check that it's OK to use them and supply those in Australia who are interested (at cost + shipping, as a community service)? Somewhere like ITEAD will do 10 boards for $10 + shipping.
With the caveot that its not been built or tested fully, the code is here and the design is open source as far as I'm concerned.... I'm just the hardware side at the moment and mostly modified Mikes original design with feedback from him and others...

But I see no issue... just bring up one board very carefully the first time...

And let us know your results.
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Re: XR8 rx telemetary sensors

Post by Imho »

aadamson wrote:
Imho wrote:Great work! I know you've made the Eagle files available to everyone but I wanted to check that it's OK to use them and supply those in Australia who are interested (at cost + shipping, as a community service)? Somewhere like ITEAD will do 10 boards for $10 + shipping.
With the caveot that its not been built or tested fully, the code is here and the design is open source as far as I'm concerned.... I'm just the hardware side at the moment and mostly modified Mikes original design with feedback from him and others...

But I see no issue... just bring up one board very carefully the first time...

And let us know your results.
Great, thanks. I'll wait a bit first and see how the first run works out.
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Re: XR8 rx telemetary sensors

Post by MikeB »

aadamson wrote:What if we put pads on the top and bottom of the board instead of holes, and mounted a 2x3 header to them. It looks like the protocol supports some form of handshake on the bus.
The SPort signal is a bi-directional bus signal. The Rx polls for sensors and they send data back over the single wire.
Sensors do daisy chain. FrSky devices do have 2, 3-pin headers to allow for this. You could add the pads to allow this to do the same, or just have a single header and plug into the 'last' sensor of the daisy chain.

To connect, we need a 3-pin, socket to socket cable. Alternatively, we wire a 'flying socket' to the board instead of the header. Only needs one, 3-pin socket and saves the cost of the header.

I had thought this could simply be the last item in the chain.

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Re: XR8 rx telemetary sensors

Post by aadamson »

MikeB wrote:
aadamson wrote:What if we put pads on the top and bottom of the board instead of holes, and mounted a 2x3 header to them. It looks like the protocol supports some form of handshake on the bus.
The SPort signal is a bi-directional bus signal. The Rx polls for sensors and they send data back over the single wire.
Sensors do daisy chain. FrSky devices do have 2, 3-pin headers to allow for this. You could add the pads to allow this to do the same, or just have a single header and plug into the 'last' sensor of the daisy chain.

To connect, we need a 3-pin, socket to socket cable. Alternatively, we wire a 'flying socket' to the board instead of the header. Only needs one, 3-pin socket and saves the cost of the header.

I had thought this could simply be the last item in the chain.

Mike.
That works too... good idea and saves some complexity... I'll get some boards/parts ordered and get a couple built up. Can you link to the latest sources for me and do you have it in git or would you like me to set it up in git?

Oh and if you haven't, it might make sense to bring out a scale factor in a define or some such so that you can scale the volt/div network as needed... it may be that you built it for 24v and then try to use it on 12 for example without changing the R's and you'd need some way to scale the smaller adc voltage.

Thanks,
Alan
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Re: XR8 rx telemetary sensors

Post by MikeB »

Source files are in this .zip:
http://openrcforums.com/forum/viewtopic ... =30#p62623.

Currently thery are not in any repository. When I get a moment I'll set up a googlecode project, that's what I'm using for everything else.

Scaling is mainly done in the transmitter already, this just needs to send an 8-bit value from the A2D for 0-3.3V.
Since we do have a 10-bit A2D, we could allow a range of 0-1.65V and use the relevant 8-bits from the A2D result. A single link option could allow for this.

Just thought, on my voltage dividers I include a 0.1uF capacitor across the 'lower' resistor (the A2D input voltage). This helps remove noise from the measured signal. Since you are including the voltage divider, you may want to include this (if it is not too late!).

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Re: XR8 rx telemetary sensors

Post by lexm »

Imho wrote:Great work! I know you've made the Eagle files available to everyone but I wanted to check that it's OK to use them and supply those in Australia who are interested (at cost + shipping, as a community service)? Somewhere like ITEAD will do 10 boards for $10 + shipping.
I'm in for some. At least 5.

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Re: XR8 rx telemetary sensors

Post by SkyNorth »

Have you thought about using a INA219 current / Voltage sensor?
This would add $2.50 to the cost , but allow for direct voltage measurement up to 26V
and with a current shunt you can measure the Amp draw from the battery.

-Brent
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Re: XR8 rx telemetary sensors

Post by aadamson »

MikeB wrote:Source files are in this .zip:
http://openrcforums.com/forum/viewtopic ... =30#p62623.

Currently thery are not in any repository. When I get a moment I'll set up a googlecode project, that's what I'm using for everything else.

Scaling is mainly done in the transmitter already, this just needs to send an 8-bit value from the A2D for 0-3.3V.
Since we do have a 10-bit A2D, we could allow a range of 0-1.65V and use the relevant 8-bits from the A2D result. A single link option could allow for this.

Just thought, on my voltage dividers I include a 0.1uF capacitor across the 'lower' resistor (the A2D input voltage). This helps remove noise from the measured signal. Since you are including the voltage divider, you may want to include this (if it is not too late!).

Mike.
Thats an easy add. I'll do that
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Re: XR8 rx telemetary sensors

Post by aadamson »

SkyNorth wrote:Have you thought about using a INA219 current / Voltage sensor?
This would add $2.50 to the cost , but allow for direct voltage measurement up to 26V
and with a current shunt you can measure the Amp draw from the battery.

-Brent
I'll take a look at this. Mike is it possible to report current and voltage? Does the tiny have i2c? Or just spi? Guess it can bit bang it if needed
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Re: X8R rx telemetary sensors

Post by MikeB »

The 'tiny13 doesn't have I2C (or any serial/SPI) and only has 1K of flash so is unlikely to be able to handle the INA219.
The 'tiny85 (/45/25) has a USI that, with software support, can do I2C. The USI uses the two pins we are already using so both would need to be moved.
We could report current and voltage by using the FASV40/100 identifiers.

My thoughts at this point are that a direct emulation of the A2 analog port of the 'D' series receiver is simple, and quite likely the most useful user reqirement. The openXsensor is much more suited to handling extra sensors.

With what we have, we can implement a direct emulation (R2=0, R3 open), or include a voltage sensor using R2 and R3 as the divider. With a software change/addition, we could measure the voltage using the full 10 bits of the A2D and use the FASV40/100 voltage ID to return a more accurate value.

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