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dc812

LMA Enhancements

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Has anyone considered adding an RX voltage check on startup to the RC-CAM LMA? I fly slope gliders, and I have built a couple and they work great when hunting for you plane, but would like to add an audible voltage check on startup and a audible voltage monitor to let me know that my RX battery is in good shape before I launch, and to monitor voltage and warn me if the RX battery get low.

What do think, anyone added this to the LMA project. Anyone interested in helping me figure out how to add this to the programming?

Let me know, could make a great project even better.

DC

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Here is an example of a Low Voltage Detect hack for LoMA.

CAM;

Thanks for the quick response.

I am new at this PIC stuff, but I can already forsee the great potential of using PICs. In regards to the LMA, I have a couple of questions:

1. Does the hack below use the RC-CAM LMA as a basis?

2. Are there any notes associated with the scymatic on operation and/or building?

3. Is the original RC-CAM LMA's programing open source...ie is that something that is available to be updated to include startup voltage status and operation voltage monitoring?

Ultimately, I would like to design/build a LMA that is able to do the following:

- Voltage check/verification with audio confirmation at startup.

- Low battery warning during operation (slopers fly a long time)

- Glitch count with audio confirmation

- LMA w/power save

- Would like all functions to be automatic, I want to avoid having to accomidate setting a jumper to check glitch count etc. This is because many slope designs bury the RX so it isn't readily accessable.

Thanks in advance for any advice/guidence.

R,

DC

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1. U1 is the LoMA PIC. If you compare the LoMA schematic to the hack schematic you will clearly see the additions.

2. LoMA's construction is shown on the project's web page. The low voltage hack is not discussed.

3. It's not open source. I don't publish source code to the rc-cam projects.

Ultimately, I would like to design/build a LMA that is able to do the following...

It would no doubt make a good entry level project to a beginning embedded designer. There are several online resources that explain R/C pulse decoding. I recall some links are in the "Useful Links" forum section.

FWIW, the LoMA design is very low parts count, which is what makes it so popular. To add low voltage detection would deviate from that since a few more parts would be needed (different microcontroller, voltage reference, pot, and some passives). That is why voltage detection was not included.

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Mr. CAM;

A couple of questions:

1. In the low voltage hack, should BAT+ be connected to the positive leg of the 4.8VDC of the male servo?

2. I noticed that there is 4.7K resistor on the signal leg of the LMA on the low voltage hack.....is that resistor only needed for the low voltage hack or has it been added for both the low voltage hack and the back LMA?

Answer to these may be obvious to some, but I'm mostly a mechanical wank, and the tron stuff is makes me scratch my head a lot!

Thanks for your help!

DC

Here is an example of a Low Voltage Detect hack for LoMA.

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1. BAT+ goes to the battery. If your Rx is NOT powered by a BEC, then you can connect BAT+ to the Rx's or servo's power.

2. The 4.7K ohm is needed for the Low Voltage Detect hack.

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Thx for the clairification.

I'll give it a shot!

DC

1. BAT+ goes to the battery. If your Rx is NOT powered by a BEC, then you can connect BAT+ to the Rx's or servo's power.

2. The 4.7K ohm is needed for the Low Voltage Detect hack.

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RC CAM,

Well, I have struck out on the low voltage hack, and I'm not quite sure where to start the troubleshooting. I am bread boarding the project to try to get it off the ground, and I have even tried to just get the 8211 to function independently of the LMA.

Here are a couple more questions that might get me going forward:

1. Looking at the MAX8211 spec sheet, it looks like output pin 4 should go high when > 1.5V is supplies to pin 3 and should provide .7mA sink when pin 3 voltage is < 1.5V. Is my interpretation correct?

2. I think part of my problem is that I don't fully understand the function of pin 2 (hysteresis). Do have a laymans explaination that a mechnical weenie like myself might understand?

Thanks in advance!

DC

1. BAT+ goes to the battery. If your Rx is NOT powered by a BEC, then you can connect BAT+ to the Rx's or servo's power.

2. The 4.7K ohm is needed for the Low Voltage Detect hack.

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The output pin of the MAX8211 is an "Open Collector" type. So, it cannot source current. You must install a pullup resistor to V+. For your bread board experiments, a 10K ohm would be fine. This resistor would need to be removed when the LoMA was installed.

Purpose of Hysterisis: http://en.wikipedia.org/wiki/Hysterisis

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The output pin of the MAX8211 is an "Open Collector" type. So, it cannot source current. You must install a pullup resistor to V+. For your bread board experiments, a 10K ohm would be fine. This resistor would need to be removed when the LoMA was installed.

Purpose of Hysterisis: http://en.wikipedia.org/wiki/Hysterisis

As far as hysterises goes, just read the Electronics Section in the article. Any of the other parts will make your brain shut down...

Ron

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Would the pull up resistor go from output (pin 4) to V+?

DC

The output pin of the MAX8211 is an "Open Collector" type. So, it cannot source current. You must install a pullup resistor to V+. For your bread board experiments, a 10K ohm would be fine. This resistor would need to be removed when the LoMA was installed.

Purpose of Hysterisis: http://en.wikipedia.org/wiki/Hysterisis

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