Updated Variant PPM (markdown)

Variant-PPM.md

@@ -1,12 +1,16 @@
 This variant can be used with PPM-SUM RC Receivers.<br>
 As opposed to PWM, it will send all channels on a single wire one after the other.<br>
-Default number of channels for PPM in config.h is 6 (Successfully tested Flysky fs-i6ab receiver with 8 channels).
+
+## Configuration/Parameters
+CONTROL_PPM_RIGHT is for the right sensor cable and is set by default to limit the noise as this cable is shorter.<br>
+You can use CONTROL_PPM_LEFT instead if you need to use the left sensor cable.<br>
+DEBUG_SERIAL will be automatically enabled on the opposite cable.<br>
+PPM_NUM_CHANNELS is the number of channels for PPM and is 6 by default. As an example Flysky fs-i6ab receiver is sending 8 channels even when used with a 6 channel transmitter<br>
 
 ## Wiring:
 * Connect PPM port of your receiver to green wire on right sensor cable(shorter)
 * PPM is highly prone to noise : keep cables short, use 100nf capacitors, use shielded cable, use ferrites, stabilize voltage
 
-
 ⚠ Red wire from sensor cable delivers 15v !!!
 Use 3.3v from programming port, 5v from hall sensor cable, or a voltage regulator.
 
@@ -23,6 +27,6 @@ If the board is [beeping](https://github.com/EmanuelFeru/hoverboard-firmware-hac
 * Check the number of channels, even if you transmitter only handles 6 channels, you receiver might transmit more channels 
 * Make sure you enabled PPM on your transmitter
 * Make sure you use the PPM port on your receiver
-* Make sure you are using the sensor cable(left or right) selected in config.h
+* Make sure you are using the sensor cable(left=CONTROL_PPM_LEFT or right=CONTROL_PPM_RIGHT) selected in config.h
 * On some boards the wire colors might differ, try the blue wire
 * You might have a defective input, because of a fried resistor or MCU pin (e.g. [issue](https://github.com/EFeru/hoverboard-firmware-hack-FOC/issues/244)), you can configure the firmware to work on the other cable