Support for HotRC / Rlaarlo receivers

[c0ldtech]

It would be nice to have support for the HotRC receivers (which are also being used by Rlaarlo it seems). I'd be more than willing to order a receiver and have it sent to someone if it helps.

[pascallanger]

Can you open one radio and receiver to see what kind of RF chip they are using?
If it looks doable (no guarantee) I would need a TX and RX set to reverse the protocol.

[c0ldtech]

I'll be receiving a set in a few days. I'll let you know and post here.

[c0ldtech]

I guess the chips you'd be interested in are the ones without markings?

[pascallanger]

The RF component looks like a LT8900 or LT8910. You could spy the SPI bus with a logic analyzer. It might be doable but it depends on the component and configuration...

[neutron-modulator]

The RF component looks like a LT8900 or LT8910. You could spy the SPI bus with a logic analyzer. It might be doable but it depends on the component and configuration...

Hi Guys. I'm willing to join this endeavour as I have a number of HotRC TX and RX.
If it helps the RF modules appear common to all transmitters and chips output is pin 4. Before Pascal posted his ic ideas, my money was on the A7105.(I'm checking a few other pins today).
I've ordered a JTAG cable and seeing if I can code a MCU to log SPI (Or just us some USB trickery). Any pointer would be appreciated. I have plenty of time but few resources.

Cheers Rod

[c0ldtech]

Unfortunately I don't have the hardware or skill to do that myself. Would you be willing to look into it? I could try sending you a receiver/transmitter combo.

[pascallanger]

Not sure how much it will cost to send a TX+RX to France versus donating to purchase a set...
Also there is no guarantee at all that this protocol can be added. If the RF chip is really a LT89xx, it has not been emulated yet apart for the Shenqi protocol which was not using special features.

[c0ldtech]

This is the one I have and should cover all available functions:

https://www.aliexpress.com/item/1005007793346834.html?spm=a2g0o.productlist.main.9.348e48aaW7WtU4&algo_pvid=b27eeace-0f88-422b-99e3-adc6ffc3069a&algo_exp_id=b27eeace-0f88-422b-99e3-adc6ffc3069a-8&pdp_ext_f=%7B%22order%22%3A%2257%22%2C%22eval%22%3A%221%22%7D&pdp_npi=4%40dis%21EUR%2138.98%2123.39%21%21%2140.03%2124.02%21%40%2112000042222094364%21sea%21DE%212333224124%21X&curPageLogUid=NbdEe5R2nVm4&utparam-url=scene%3Asearch%7Cquery_from%3A

I'd gladly donate the amount it costs, I'd see it as my thanks to the community. Would that be OK?

And I know it might not work out, but it would be nice if it did.

[pascallanger]

I can take a look but once again there is no warranty that it will work and that will take some time (weeks).
I'm in France so look at the shipping cost both ways vs donating to purchase a set.

[c0ldtech]

Yes, seems like it. Right now I have another receiver in the car in order to be able to use the MT12. As expected, just plugging the lights into the new receiver doesn't do anything. I needed a dedicated light controller to make them work.

So the lights seem to be just a regular LED strip without any included logic. That in turn should mean channel 5 is just a simple on/off. On the original remote it's dedicated to a regular on/off button, no additional states or anything.

[pascallanger]

I've placed the order, let's see when I get it.

[wmlex]

@pascallanger Is there any news on adding support for these receivers?

[Johanl1964]

I've placed the order, let's see when I get it.

I'm hoping for this too, have some RX I'd like to try on 4in1!

[maxim-gwc30]

I can take a look but once again there is no warranty that it will work and that will take some time (weeks). I'm in France so look at the shipping cost both ways vs donating to purchase a set.

Hi Pascal. I’m working on the same HOTRC protocol. I have opened a transmitter and can capture the RF SPI bus with a logic analyzer. Did you make any progress after receiving the HOTRC TX/RX set? If useful, I can provide board photos and SPI captures.

[WZ9V]

It looks like the MEUS stuff on Amazon uses this protocol also. Having this would be great since they have some $18 RX with 6 channels, gyro and battery telemetry.