Who wants to build and sell varios for a french company?

[bertrand35]

Hi,
I have another order of 10 openXvarios for a french company. I sell them 40€ / vario (vario + main batt voltage). But I don't have enough time to continue this work. If someone is interested, please contact me on my email.
Thanks,
Bertrand

[mstrens]

Please that a new version of openXsensor will soon be available.
It will support 2 MS5611 and an airspeed sensor (4525DO).

Soldering all those components becomes difficult.
It would be much easier if someone makes a pcb board.
I think it makes sense to propose a small pcb board that would just fit on top of Arduino pro mini and that would allow direct soldering of 4525DO, several voltage dividers, a push button, cable to PPM channel, cable to SPORT/Hub connector. This board could also have some connectors to 1 (or 2) MS5611, to external temperature and to Hall effect probe (RPM). Optionally it could allow soldering a voltage regualtor.
I can make a schema if someone is interested.

[bertrand35]

Why not!

[jpparisy]

If your schema is in Eagle format, I can generate the Gerber files needed by Itead Studio to produce PCB. The price for 10 PCB is about $14.00, port included.

[jhsa]

Why having the arduino board? Just build your own arduino in the same board.

[bertrand35]

1$40 for each PCB is indeed nothing. Which would be the minimum quantity? 50 would be ok?

[andrewju]

It would be much easier if someone makes a pcb board.
I think it makes sense to propose a small pcb board that would just fit on top of Arduino pro mini and that would allow direct soldering of 4525DO, several voltage dividers, a push button, cable to PPM channel, cable to SPORT/Hub connector. This board could also have some connectors to 1 (or 2) MS5611, to external temperature and to Hall effect probe (RPM). Optionally it could allow soldering a voltage regualtor.
I can make a schema if someone is interested.

This is a great idea!
I'm definitely interested!
I would also be willing to buy some boards if we decide to place a group order somewhere (like iteadstudio or oshpark).

P.S. Mmm... I can also put together some varios for the French company or for forum members (at a cost of components + shipping for forum members, of course)... Shipping may take a couple of weeks more than if the varios were made directly in EU, otherwise it should be fine...

[jpparisy]

1$40 for each PCB is indeed nothing. Which would be the minimum quantity? 50 would be ok?

The minimum quantity is 10 (ten) for $9.95, excluding the port. The more you order, the more the cost's port is less for each PCB.

I prefer Itead: if your Gerber files are correct, the PCB are delivered in Europe 10 days after the order, except when there are chinese holidays.

[mstrens]

Now we have 2 questions:
1) which option for the board :
option 1 : having a board having the same size as the Arduino pro mini and to put on top of an Arduino pro mini
option 2 : put all components (including CPU, voltage regulator, quartz, ...) on a single board.

Personnally, I think that option 1 is better because:
- you avoid all the work of soldering small smd components and connecting the 2 board toegether would be very easy because the pins would just be in front each others so straight staps would do the job.
- you have the already the bootloader loaded in the CPU (so you can upload the firmware with a cheap FTDI.
- cost is perhaps even cheaper because you find full Arduino pro mini for about 3 € on ebay (delivery included)

2) who is able to design the PCB.
I think, once the PCB is designed, it is even possible to find chinese suppliers that will make 10 for about 10 $ delivery to Europe included.

[andrewju]

Option 1 will be cheaper and easier to assemble. The Arduino Pro Mini is actually less than $3 on E-bay, shipping included (the Arduino components alone will likely cost more than that).

Option 2 will be lighter (which is sometimes important) and will probably look nicer. Also, there's more fun putting the entire board together...

Ideally, both options should co-exist...

[jpparisy]

I also prefer the option 1, more in the spirit of the Arduino system.

If nobody else wants to do the job, I can design the PCB if there is a good schema and a complete list of components, including the links to their datasheets.

[mstrens]

I also prefer the option 1, more in the spirit of the Arduino system.

If nobody else wants to do the job, I can design the PCB if there is a good schema and a complete list of components, including the links to their datasheets.

For option 1, I am currently drawing a schema in Eagle but it is not easy for me to make a clear schema.
I never use Eagle before.
It is mainly difficult to find the right components in the library.

But in fact the board has only a few basic components: resistors, capacitors, 1 micro pushbutton and 1 IC (4525DO - 8 pin DIL but the distance between 2 lines is 0.5 inch).
There are quite many pins for the connection with arduino, with the GY63 (MS5611 sensor), Lipo or battery to measure and for several external 3 pins sensors (current sensor, temperature sensor, Hall effect sensor).
If there is still some space a voltage regulator (and capacitors) could be added as an option.
The main advantage of such a board is that there is no need for cabling anymore.

[jhsa]

And which current sensor will the board support?? there are a few different flavors and sizes

I recently bought some MC78M08CDT, which are 8V 500mA regulators in a D-Pak package because I've noticed that my arduino's regulator was a bit too warm for my taste with a 3 cell lipo, even if it is supposed to work well with it. Which it did for about a year now.. But anyway, I've decided that my next one will have an 8V regulator in between.
A friend of mine already designed a couple boards for the arduino, vario, current sensor etc.. He reads this forum and will post his files if he thinks it is appropriate

João

[MikeB]

One of the biggest problems for the firmware of the openXsensor is the software driving of the serial interface, particularly when in SPort mode.
If an addon (or complete new) board is being considered, please consider including suitable inverting circuitry to allow the hardware serial port to be used. I can, of course, draw up the required circuitry.
Having this, would also make operating at a lower clock frequency work better.
Personally, if a complete new board is produced, I would propose having a 3.3V regulator, and operating at 12MHz.

Mike.

[jhsa]

Then we would also need a 5V regulator because many of the current sensors work better with 5V the allegro sensor I tested, despite the datasheet saying that it could work at 3.3V, had its accuracy reduced.. also if the chip is working at 3.3V the sensors would have to output maximum of 3.3V right? That would.mean a voltage divider on the sensor output?
so, in my opinion I would keep it at 5V.

João

[mstrens]

One of the biggest problems for the firmware of the openXsensor is the software driving of the serial interface, particularly when in SPort mode.
If an addon (or complete new) board is being considered, please consider including suitable inverting circuitry to allow the hardware serial port to be used. I can, of course, draw up the required circuitry.

Mike.

@Mike,
If we implement an inverter, I presume that the idea is to be able to use the internal hardware UART (from 328P) instead of having to implement code for a software UART (for the SPORT/HUB).

I still have a question about this:
I think that 328P has only one hardware UART.
If it is being used for SPORT/HUB, will it still be possible to use command like Serial.print to communicate with the PC terminal while debugging?
Whitout those commands I can't develop the software.

On the other side the code that you wrote for SPORT (and HUB) seems to work fine (even on a CPU at 8Mhz). So why changing this code.

If a complete new board is developped, would it not be better to consider another CPU like the one used in the Tensy. I think it has 3 UART.
Further more, we slowly reach the limit of the 32k program memory from the 328p when all current options are activated (and being in debug mode).
But I think that we are then not anymore in the original spirit: having a very cheap multi sensors that can be build without any special skill (just using a small soldering iron).

[Tempo]

I prefer Teensy 2.0 instead of Arduino pro mini for openXsensor:
http://www.pjrc.com/teensy/index.html

[Tempo]

...
If a complete new board is developped, would it not be better to consider another CPU like the one used in the Tensy. I think it has 3 UART.
Further more, we slowly reach the limit of the 32k program memory from the 328p when all current options are activated (and being in debug mode).
But I think that we are then not anymore in the original spirit: having a very cheap multi sensors that can be build without any special skill (just using a small soldering iron).

Teensy 3.1 has 3 UART and overkill of memory and other features for openxsensor

teensy31.png (101.29 KiB) Viewed 12893 times

[mstrens]

Here a draft of the schematic of a board to be put on top of an Arduino Pro Mini.
It is made in Eagle.
Sorry if it is not better but it was my first test with Eagle and I did not find the right components.
I tried to make it as flexible as possible.
It allows:
- to measure up to 6 lipo cells
- to be connected to 1 or 2 GY63 (MS5611) sensor (=> altitude + uncompensated and compensated vario with TEK probe)
- to be connected to a 4525DO-DS5AI001DP differential pressure sensor ( connected to a Prandtl probe)in order to get airspeed (up to 360 km/h) and perhaps compensated vario without TEK probe.
- to be connected to an (external) Hall effect sensor
- to be connected to (external) sensors to measure e.g. a current, a temperature or just a battery voltage)
- to be connected to SPORT or rx (on D serie Rx) (= sending telemetry data)
- to be connected to a channel from the receiver in order to adjust some parameters from TX (vario sensitivity, selection between compensated/uncompensated vario, reset of calibration of airspeed sensor, vario compensation factor)
- to be connected to A2 from old receiver (without telemetry) in order to send an analog voltage based on the vertical speed
- to select the way it is power supplied (External battery, Rx via SPORT, Rx via PPM) , optionally bypassing the internal arduino regulator (when only one lipo cell is used), optionally having an additional voltage regulator (when battery voltage is to high).
- to have an on board or external push (reset) button for some OXS function (e.g. reset of consumption).

If someone accept to work further on in order to draw the board, he can contact me via private message and I can explain furthermore how I see the disposition of the components. There are a few attention points. it is also possible to use other pin from arduino in some case if it makes the layout better.
I already started but only with the used pin from the arduino.
One of the challenge is to keep the size small (ideally equal to the arduino).
Another one is to take care that not all arduino boards available on ebay have the pin A4 A5 A6 A7 on the same location. I would suggest to support at least 2 dispositions on the 3 (at least) that exist.

[mstrens]

...
If a complete new board is developped, would it not be better to consider another CPU like the one used in the Tensy. I think it has 3 UART.
Further more, we slowly reach the limit of the 32k program memory from the 328p when all current options are activated (and being in debug mode).
But I think that we are then not anymore in the original spirit: having a very cheap multi sensors that can be build without any special skill (just using a small soldering iron).

Teensy 3.1 has 3 UART and overkill of memory and other features for openxsensor

teensy31.png

This would be a good solution but the price is not the same as the one of an arduino pro mini (3 €).
Currently the arduino pro mini still do the job. So why changing now?

[jhsa]

Agree..
No need to change board. I think..

[mstrens]

I prefer Teensy 2.0 instead of Arduino pro mini for openXsensor:
http://www.pjrc.com/teensy/index.html

Teensy.gif

@Tempo,
Except the USB connector, why do you prefer the Teensy 2.0.?
I do not think that the chip (32U4) is so different from the (328P) from the arduino pro mini and it cost about 5 X more.

[jhsa]

if you want USB, get an arduino Nano Still compatible with the code

João

[davx]

Hi,

Currently the arduino pro mini still do the job. So why changing now?

I also agree, but at least, if OXS supports another board, I'd like it keeps the arduino pro mini compatibility.

[Tempo]

I prefer Teensy 2.0 instead of Arduino pro mini for openXsensor:
http://www.pjrc.com/teensy/index.html

Teensy.gif

@Tempo,
Except the USB connector, why do you prefer the Teensy 2.0.?
I do not think that the chip (32U4) is so different from the (328P) from the arduino pro mini and it cost about 5 X more.

"Teensy is very easy to use, because uploading takes place on the USB port, which is not shared with serial. "
More informations: http://www.pjrc.com/teensy/teensyduino.html

[jhsa]

it's going to be more expensive.. better to buy the frsky sensors then
But as long as the support for the pro mini doesn't end, other people use whatever is best for them

João

[MikeB]

My copy of Eagle is too old to read the files, so I can't help there.
Suggestions:
Use the hardware serial for normal use and, if needed, a software serial for debug.
Keep to the Pro Mini, but add the hardware on the addon board to allow the hardware serial to drive the SPort 'properly'.
Consider adding a 4.096V voltage reference to allow for accurate and repeatable analog measurements.

Mike.

[mstrens]

My copy of Eagle is too old to read the files, so I can't help there.
Suggestions:
Use the hardware serial for normal use and, if needed, a software serial for debug.
Keep to the Pro Mini, but add the hardware on the addon board to allow the hardware serial to drive the SPort 'properly'.
Consider adding a 4.096V voltage reference to allow for accurate and repeatable analog measurements.

Mike.

@Mike,
Here some print screen of the proposed schema and board. Those file are just png file so you could look at them.
About the board, I did not yet implemented the resistors, capacitors and regulator.
I only tried to implement all connectors, the 4525DO and reserve the space on top for the MS5611.

It was not possible to keep the size of arduino pro mini. I am 0.4 inch longer.
It will be a nice challenge drawing all the connections and adding the missing components.

I am not convinced that using the internal UART is the best solution:
I imagine that many users would like to build OXS without the additional board (you need to get it, it's add weight and size). So for a user that want to use OXS with one sensor (e.g. a current sensor) it does not make sense to use the additional board. It is better to consider this board as an option.
If the code of OXS uses only the internal UART, a user who just want e.g. a current sensor would be obliged to add all the components for inverting the signal.
The software serial you made works fine as far I know.

If an inverter would be added, I think it makes more sense to use it in order to read the SBUS.
This would allow to have more controls on OXS behaviour from the TX than just with one PPM channel.
I have already implemented 4 kinds of command on a single PPM (adjust sensitivy, adjust compensation, select compensated/uncompensated vario, reset airspeed). It will be difficult to do more with one PPM.

[mstrens]

Here already an version 2 of the draft of a board to put on top of Arduino pro mini.
I added a decoupling capa (for 4525DO) and I tried to implements all connectors and the 4525DO + MS5611.
This part was quite critical in order to be OK from a mechanical point of view.

Can some one continue implementing the other components.
Here already some suggestions:
If required all resistors R1...R6 could be implemented on the other side. Once installed there is no real reason to change them.
It makes more sense I think to let R11...R16 on the main side because they should be changed if the voltage range to measure change.
The capa C1...C6 are "nice to have". So if there is no enough space, they can be ommitted.
The pushbutton is also a component that could best be external (just 2 pin connector to foreseen)
The voltage regulator could be a classical 3 pins and not a D pack (it takes less space on the board)

[jhsa]

So for a user that want to use OXS with one sensor (e.g. a current sensor) it does not make sense to use the additional board.

Of course it does make sense.. Specially with a current sensor.. That is the reason why I made an extra board for mine.
If you only have a vario and 2 resistors for the voltage sensor, then it doesn't make sense to have an additional board as you can solder all to the arduino board and just shrink tube it.. That is how I did my vario.. more or less like Rainer did his.

João