Reply to Jim M. (customer) re. G9X v4 board questions.

[Bryan]

Jim

I'm 'connecting' this message to the gruvin9x discussion group. Trust you won't mind. I've taken steps to obscure your email address, lest it be broadcast without permission. Please reply to this message, rather than using the shop online message form, so that others may have the benefit and group system gets to archive our conversation. Thanks.

On 22 September 2012 20:22, Jim McKeown <jimm***@shaw.ca> wrote:

Customer message: I found our Q&A on the 9x google forum. It answers my questions.
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Glad to know.
 

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Now I believe that I can mount my smartieparts over the v4.2 board and retain my connection to download firmware.
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Nope -- well, not installed over the board, like it is for the stock factory Turnigy board anyway. These test pads are not present to make the connection from the pogo pins.

You could conceivably run wires from the pogo pin positions to the ISP programming header in the lower right of the G9X board. However, I do not know if the USBasp implementation in the SmartieParts programmer has the patch to allow it to operate correctly with the larger ATmega2560 chip. (Likely not, I'm afraid.)

We made the gProg programmer for this purpose. It also has the USB socket in battery compartment thing. But you can use any compatible USB AVR programmer, since the G9X board has the industry standard 6-pin ISP programming header -- located at the lower right corner.

MUCH BETTER (in theory) -- there's also a USB bootloader firmware coming soon. It's currently in testing and final development. The bootloader allows a USB socket to be connected directly to the G9X board (lower edge, just left of center) without a separate AVR programmer -- and to be used for firmware and EEPROM data transfer. The bootloader firmware make the G(X board appear as a USBasp AVR programmer n the USB bus. (Thanks to the V-USB project for doing the leg work on this one!)

The catch of course is that the bootloader firmware has to be loaded onto the board, in the first place. My plan is to have the next batch of boards shipped with the bootloader (and current open9x firmware) pre-installed. Then, unless something goes badly wrong, users should no longer need a separate AVR programmer. I do have some concerns still about this, but we can discuss it all in more detail some other time, if interested.

For the record, the only SmartieParts board that is compatible with the G9X v4.2 board is the little 1" square EL back-light driver, which as you no doubt know, is now not recommended, in favour of using the newly available LED back-light modules. I am not certain if open9x supports this board as of right now. It would be a simple fix to do so though, in the unlikely event someone insists on using the nowadays inferior back-light technology.

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I believe that I can reconnect my LED to the v4.2 board and by pass the smartieparts board.
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Yes. The v4.2 G9X board has an LED back-light connector for this purpose. Please note the potential to blow up your back-light if wired incorrectly, as clearly explained in the G9X FAQ you found.
 

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I believe I can wire the DIY osd to the v4.2 board by sharing the terminals on the back board with the DIY FySky.
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I don't know anything about any OSD system, sorry.
 

As you know they used to connect the 2 way osd system.

No, I don't know anything about that, sorry. [More on this below, in response to your original message, before finding the FAQ.]
 

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The location of the memory card seems to conflict with the location of the speaker, and the DIY FrSky.
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There is no conflict, if installed as I have done. (See below, plus attached images.)

The speaker is hot-glue mounted, right at the air-vents (front grill.) The SD-card board is above that and the original Turnigy power-switch board above that, in its original position of course -- but with the piezo beeper moved to the opposite side. There are photos of all this on store site, here.  I have attached three of the store images to this email, also. (There ought to be similar photos on the project site -- in the FAQ even ... but I don't see them. Will remedy that shortly.)

I don't know anything about any DIY Fr-Sky installation in that area. Personally, I would mount the Fr-Sky DIY module either in the rear casing TX module compartment or on the rear casing's mostly blank PCB area, centered such that it ends up floating above the power switch board (well beneath, during practical operation I guess).

It might pay to remove the two big chrome, spring-steel earth terminals (if even present on your model 9X) since they are not really needed for 2.4GHz operation.
 

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Can't tell from the pictures. The 24 ohm speaker system can be used for amplified head phones if they actually exist in my price range. Please correct anything that is wrong with my thinking.
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There should be no need to amplify anything for headphones. Just hook'em up directly. Some cheapie, thrift store ("Two dollar shop", here) 'phones should be fine. I'd be very surprised if there wasn't plenty of volume in this case -- even with the worst headphones. You might even need to knock it back some, with a resistor.

- - -

Referring now to your previous, email on topics not covered above or in the FAQ you have now found ...

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I have a DIY frsky osd system that is not connected to the turnigy board. Tried it several times without success. I use the small optional screen to observe the osd sensors.
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I'm a little bit confused here. In my mind, "OSD" stands for, "On Screen Display" and is used in the context of embedding telemetry data into an existing video feed -- like those used for FPV flying (where you fly a plane from inside the cockpit, via camera and real-time video.) So not quite sure what you are referring to in this instance, since you've not mentioned anything about video.

If you are referring to the display of Fr-Sky telemetry data, then I should note that the open9x firmware has significant support for this on the transmitter's main display. that said, you could probably get away with connecting the telemetry Trx data to both the G9X board's pseudo-RS232 RX pin and your 'OSD' board, if I'm guessing right.

As an aside; In fact, with the G9X board's custom designed pseudo-RS232 interface, you should also be able to connect Rxd (if needed by your 'OSD' thingy -- for alarm setting) without any electrical conflict. Things won't work so well if both your 'OSD' board and the G9X board try to send data to the Fr-Sky TX module at the same time. But the port is otherwise shareable for both TX and RX. This is rather non-standard for RS-232 comms and is not supported by the likes of the MAX3232 chip being used by many for voltage level conversion, against my advice.

Ultimately, I think you'll be better off retiring the 'OSD' board and using the main screen instead, now that you can --  assuming I'm guessing right here, at all.

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The voice over system that is being discussed in the forum is compatible with the sound system? stupid
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You might have meant, "does not use the same sound system. stupid". If so, then correct (about it not using the same system.) They are using the SOMO14 sound module, which has its only little MMC card for audio files and its own (quite loud) speaker driver. However, mixing that into the same sound output as the main board -- for use in your headphones -- should be a simple matter of a couple resistors and/or capacitors, forming a common, passive audio mixer. Or not -- the main board audio might end up too quiet. I haven't tried it since, sadly, I don't possess a SOMO14 module and have thus not played with any of the voice-over stuff, to date.
 

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I have a 6 position rotary switch in position 2. Is there any problem here?
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I think the open9x firmware has an option for that 6-pos switch. Not certain. I'm sure they would add it though, if not. I do recall seeing how it was done, in a forum post somewhere. But I don't visit forums very often. Too much data and I 'overload' too easily. :-P
 

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Has anything been done about the voltage regulator. I have replaced a few.
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I am not aware of any problems with the voltage regulator on the G9X board. I have heard of a just one incident where a faulty 5V regulator occurred on a Turnigy board -- and I have seen the big, fat retro-fit regulator on the ARM board, guessing their board draw much more current, with the more powerful MCU chip and all. But none of that is relevant here, I don't think.

On the G9X board, the 5V controller system draws about 30mA max., from the main regulator. The reg. itself is rated to 100mA. It doesn't even get warm, far as I can recall. The LED back-light has its own dedicated 5V reg., tapped off the main BATT+ feed -- and fused. (A no-fuss, auto-resetting SMD fuse, on the PCB.)
 

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What is the recommended battery voltage. 12 volts seemed a bit high.
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Hmmm. Maybe people are experiencing regulator heating when running "12V"? I doubt it though. We're not drawing any more current than the original Turnigy board was -- and so quite by design. Actually, 8 new AA alkalines can be as high as 14.2V!! I definitely do not recommend that.

I use TrustFire (protected) 2500mAH Li-Ion cells from DealExtreme.com. They're just US$6.94 a pair if you order 3 sets ($7.99 if not) -- and free shipping in either case.

Note that these are the lower current, "protected" Li-Po version, with the additional protector boards installed. They look almost identical in almost every way to the higher current handling l version without protector board, which have quite different operating characteristics and are NOT so safe to charge without balancing, as is just fine with the other. Do not confuse them when ordering. I have done, twice. Frustrating! But I'm on to their game now. :P

I have tested these cells for run time (Fr-Sky transmitter module) at over 6 hours, from a starting voltage of 8.5V down to about 7.8V. Although they're will run the system reliably down to 7.4V or less, I figured six hours was more than long enough and so I use a 7.7V alarm setting, to be super safe.

Oh -- I have had one dud cells in a pair from DealExtreme. My attitude though is that these things are ultra cheap for what you're getting -- so just order 3 sets and accept that you *might* get one dud. IMO, this is just "the Chinese way". Putting all moaning aside and just adapting to it can save a lot of money, if we are only willing to do our own quality control! Why pay mega-nucks to have other people do Q.C, when most items have no fault? *wink*

My charger for these cells is a modified (couple resistors) 9V switch-mode 'wall wart' plug-pack, which now outputs 10.1VDC and is plugged directly into the existing charger port on the side of the radio. There's no current limiting resistor, that being the reason I modified its voltage to precisely 10.1V :-). This effectively limits charge current to about 500mA starting/maximum, which I've also tested over 24+ hours, to ensure no over-heating or what have you.

(I don't think I've published the above battery information anywhere else, now that I think of it.)

Others are using 3S 'LiFe' (Lithium Iron (not ion) Phosphate -- one of the Lithium Ion family) packs from HobbyKing.com. These are much safer from a charging point of view, than Lithium-Polymer and also more tolerant of being fully discharged, if you leave your radio on over night by accident. These have a nominal 9.9V full charge voltage, which should be just fine -- though I've not personally tried it.

One of the reasons I prefer the TrustFire cells is because they have a higher internal resistance, which manifests as a much wider voltage span, during discharge. In other words, I can confidently know how much time I have left during the discharge cycle, whereas with the more higher spec'd Li-Fe cells, there tends to be a much flatter discharge curve, resulting in a quite sudden drop-off at the end. That's not so good if one needs time to land an air plane, after the low-batt alarm has started!

In other words, I get the same safety and convenience as I might out of expensive and physically heavier, Ni-MH cells -- without the risks of normal Li-Po / Le-Fe -- and all for pennies on the dollar, by comparison.

Oh and yes -- the cells do fit in the transmitter battery compartment -- just. They sit at a 45º angle and cannot have any tape of heat-shrink wrapped around them, if such a fit is desired. So instead, I simply hot-glue mine together, using a strip of glue down each side of the 'V', between the cells. These cells are also shorter than the Li-Fe option, affording some spare space in the compartment, which I use for storing my Spektrum binding plug.

Hope that helps!

--
Bryan.