getting PPM signal from old old 27Mhz radio controller

 I have an old sanwa car controller, it old but in good Sharpe.



I want to convert it to modern 2.4G or LRS, since old AM/FM could be triky these days, when all your analog parts are 20years old.


There is only one main chip on PCB, it's OKI  L9362...
you can still find the scanned version of datasheet...
it takes 4 VR cahnnels into PPM out put...
supply voltage range is 6-13V...

It has a internal regulator, so the out put is 3.8V...


Referencing to data sheet, I power the board with 10V, and take the out put signal with scope. I do get 2 channels.
first slot is steeling

Here is the back side of th IC, the red V is Vcc, the blue V is Vref(3.8V, where VR is connected to). 
The you have channel 1 and channel2, the channel 3 and 4 are bounded, but not grounded.



Today, with arduino, it's quite easy to read out the PPM with this library:

https://github.com/dimag0g/PPM-reader

it use interrupt so, no delay on your system, and can pretty mature.

now, the question is: what RF  to use?

There is not much space, a single MCU with RF is the way to go.

NRF 24L01 is RF only, I guess it would be possible to go with ESP8266, there is a ESP now protocol, which could be OK for RC.


8266 for TX and RC with servo out put

https://github.com/PepeTheFroggie/espnow_RC_RX 

https://github.com/PepeTheFroggie/espnow_RC_TX

support telemetry and IIC sensors

https://github.com/BogdanTheGeek/ESP_RC



I first test ppm reader on ESP8266 D1mini, the pin naming on d1 mini is quite confusing. And the interrupt on D1 is some how tricky.

https://forum.mysensors.org/topic/11822/my-wemos-d1-mini-adventures-interrupts-on-pins-d3-and-d4

I tried to do the fix in the PPM reader lib, it did not work out...

I change to :  https://github.com/PepeTheFroggie  he use D1 mini as board, I guess it should work...

The PPMin Pin, I changed to GPIO15(D8) on D1 mini. Modify the code to 2 CH...

The ppm voltage out put of OKI, is related to the battery in put, so I use a level shifter to lower and fix the voltage at 2.2V...(not sure why it's 2.2v, but it works...)



The Rx code works just fine, the 2 servos is at GPIO12(D6)/GPIO14(D5)


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