New Lemon transmitter module, DIY & JR formats

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Shaun
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Re: New Lemon transmitter module, DIY & JR formats

Post by Shaun »

Here you go Stormer, first show the wife this:

But Goldman, a microbiologist at Rutgers New Jersey Medical School in Newark, decided to take a closer look at the evidence around fomites. What he found was that there was little to support the idea that SARS-CoV-2 passes from one person to another through contaminated surfaces. He wrote a pointed commentary for The Lancet Infectious Diseases in July, arguing that surfaces presented relatively little risk of transmitting the virus2.

Then open your package straight away..

:D :D
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stuart mackay
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Re: New Lemon transmitter module, DIY & JR formats

Post by stuart mackay »

Well the missus is doing Covid testing and I opened the parcel and we swabbed it, guess what it was negative! :)
My DIY module found its way with one of Mike's Encoders into this fella..
DSCF5485.JPG
Range and boot up time is comparable with the Orange DSM modules, but as Paul has said it is so tiny...not much bigger than a Digispark!
stormer254
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Re: New Lemon transmitter module, DIY & JR formats

Post by stormer254 »

Several bottles of wine later with her indoors snoring on the sofa off I sneak to the shed, module in hand, read the instructions before inserting the module, possibly a first for me, being a bloke it's usually read them as a last resort, and bingo it works! Several DSM2 models bound and I can switch between several models on the TX memory without having to rebind. I will try some more tomorrow but hopefully this solves my problem. The only thing I can see that might be a problem is that changing between DSM2 and DSMX is that I will need to rebind, the instructions seem to say to me that the module remembers the last bind protocol. Not too much of a problem as I only have two DSMX RX and twenty DSM2 RX. I have taken the liberty of attaching the instructions if any one would care to comment on this, but pleas be gentle me with if you do, after all I was a builder\!
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Lemon DSMP - Plug&Go Tx Module Instructions v.1 FNL .pdf
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Wayne_H
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Re: New Lemon transmitter module, DIY & JR formats

Post by Wayne_H »

stormer254 wrote: 23 Mar 2021, 22:52 Several bottles of wine later with her indoors snoring on the sofa off I sneak to the shed, module in hand, ........
smooth operator 8-)
Cheers,

Wayne
Once a Retrobate, always a Retrobate............ ;)
Dave McDDD
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Joined: 28 Apr 2020, 19:37

Re: New Lemon transmitter module, DIY & JR formats

Post by Dave McDDD »

I'm hoping that someone here on Mode Zero can help me with a problem I'm having with 5 DIY modules, and one Plug & Go module.

When these Lemon modules are bound to a DSM2 receiver, the brownout warning light immediately begins flashing as soon as the receiver is powered up, even though the transmitter power was cycled off, then turned back on before powering up the receiver again. I strongly suspect that these Lemon modules are not changing the two DSM2 frequencies when the modules are turned back on, which would explain the blinking brownout light each time the receiver is powered up.

Here is a quote from a Spektrum AR9100 manual that describes how the brownout detection light operates:
"When power is restored, the receivers will immediately attempt to reconnect to the last two frequencies they were connected to. If the two frequencies are present (the transmitter was left on) the system reconnects typically about 4ms. The receivers will then blink indicating a brownout has occurred."

Based on the comments in the RC Groups thread about the Lemon transmitter modules, apparently the pre-production units did choose different frequencies each time they were powered back up, so they didn't cause the DSM2 receiver brownout light to activate at startup.

In my case, all of the Lemon transmitter modules were production units purchased and shipped after March 5, 2021, and all them are causing the DSM2 brownout light to activate each time the receiver is powered up. This behavior does not happen with any of my other DSM2 capable transmitters, only the Lemon modules cause this problem.

Does anybody in this thread have a production unit purchased after March 5, 2021?
If so, can you verify that these modules never change their two DSM2 frequencies?

Here is the procedure I've been using with the production Lemon modules that result in a blinking DSM2 receiver brownout light during startup:

1. Bind DSM2 receiver to DIY module. Wait for steady on receiver light indicating bind is complete. Remove bind plug. Turn off receiver. Turn off transmitter.

2. Turn on transmitter, wait for green light on DIY module. Turn on receiver. DSM2 light comes on and stays steady on. I consider this to be normal behavior. Turn off receiver. Turn off transmitter.

3. Verify that both the receiver and the transmitter are turned off. Turn on transmitter, wait for green light on DIY module. Turn on receiver. DSM2 receiver now has a blinking "power interruption" warning light in the receiver. The servos respond to the transmitter normally, but the DSM2 receiver has falsely detected a "power interruption", while also falsely detecting that the transmitter power had not been cycled.

4. Until starting over at step 1, repeating step 3 always results in the falsely detected blinking "power interruption" warning light. While it doesn't rank up there with tornados, hurricanes, and earthquakes, it still isn't normal behavior for a DSM2 system.
Built a Heathkit GD-19 in 1969. Been flying RC ever since!
bluejets
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Re: New Lemon transmitter module, DIY & JR formats

Post by bluejets »

Low rx battery level or fault perhaps..??
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Mike_K
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Re: New Lemon transmitter module, DIY & JR formats

Post by Mike_K »

I had a quick try with a LemonRX DIY module with an AR9100 power safe DSM2 Rx and yes if I turn the transmitter back on fairly quickly I get the same results. But I think this maybe a case of Lemon Rx being smarter than Spektrum themselves! If you think about it, the receiver is remembering the last channels it used, so why shouldn't the transmitter module also remember?

So why not re-use the same two channels as long as they are still clear and not being used by another transmitter? So to try this out I set an old 2.4GHz analogue video transmitter to swamp where one of the Lemon Rx channels was and when it was powered up it did correctly choose another channel (but the other channel previously used was still clear and was reused). Doing what Lemon Rx is doing in DSM2 mode has the benefit that if a transmitter with a Lemon Rx module is inadvertently turned off and quickly back on (and it's surprising how many people I know have done this at the flying field) a DSM2 Rx should re bind quicker than with a genuine Spektrum Tx.

If you want to check what is going on then Martin (Ceptimus on this forum) designed an open source 2.4GHz monitor that displays what channels that are in use. It's based on a cheap nRF24L01+ module, OLED and Arduino. Since then our Chinese friends have copied it without acknowledging his work, but I think even Martin has bought one as they are more neatly packaged than a DIY made one.

https://www.banggood.com/Lantian-Mini-H ... rehouse=CN

The other thing I've noticed is that a genuine Spektrum DSM2 transmitter often has the two 2.4GHz channels nearly next to each other, which isn't ideal as one source of 2.4GHz noise on that part of the spectrum would effect both channels, my Lemon Rx module always seemed to space them apart. But I haven't turned it on and off enough times to know if this is by design or by chance.

I think it is refreshing to know that Lemon Rx has designed their own product (albeit using Spektrum protocol), not just copied Spektrum's code.

Cheers Mike
Dave McDDD
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Re: New Lemon transmitter module, DIY & JR formats

Post by Dave McDDD »

bluejets wrote: 29 Apr 2021, 08:05 Low rx battery level or fault perhaps..??
The receiver battery is a 1100 mah Life in good condition, so the voltage to the receiver is 6.6 volts. The blinking light always occurs even without any servos plugged into the receiver. There is no way a DSM2 receiver can load down a 1100 mah Life battery all by itself far enough to cause a brownout detection to trigger correctly. I've also used ESCs and other batteries, and the result is always the same when using any of the Lemon transmitter modules. The brownout light immediately starts blinking as soon as the receiver is powered up.

I have around 30 DSM2 receivers. Five of them are Lemon 6 channel Featherweights. The others are Orange 6 channel and one 7 channel. They are the perfect choice for cheap/expendable/durable planes. While I haven't tested all 30 of these DSM2 receivers with the Lemon transmitter modules, all of the DSM2 receivers that I have tested always startup with a blinking brownout light, but ONLY when using the Lemon transmitter modules. (5 DIY modules, 1 plug and go module)
Built a Heathkit GD-19 in 1969. Been flying RC ever since!
bluejets
Posts: 316
Joined: 19 Jun 2019, 04:09

Re: New Lemon transmitter module, DIY & JR formats

Post by bluejets »

So it's the same battery used on all when the fault occurs...?

As I said either low battery or a faulty battery in that the connections are dodgy or a break in the plug.

If the unit is that sensitive it could be that it's more along the lines of "contact bounce" as in switches in uC circuits.

Brownouts occur when the supply drops below a defined level and then reinstates.
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