Still trying to wrap my head around PWM & PPM

New to UAS spent 2 years building S500mm Quad-copter “X” Frame.

“X” Frame : S500mm or 21" across “X” Arms.
Flight Controller: Pixhawk 1 FMU 2 (From China) says Pixhawk 2.4.8 (Amazon) Flashed w/Firmware 1.10.1 Latest FMU 3 (via DEV Master & SYS_FMU_UPDATE-Enabled QGC.
RC Transmitter: FlySky FS-i6X
RC Receiver : Flysky- ia6B (PPM-output)
4-Motors : Sunnysky X3108S-15 900Kv
4-ESC’s : Hobbypower SimonK (Pre-flashed) 30amp, BEC-5Vdc, 2amp
Power Module : Unit that came w/Pixhawk FC.
QGROUNDCONTROL -Daily Build per Don/here.
I know the difference between PWM and PPM. I read up on both. Read Pixhawk wiring layout, PWM vs. PPM. Can’t determine Pixhawk requirement, PWM or PPM. RC-Receiver output is PPM, 1 wire for all 4 Channels/Motors ECS’s. Using White signal wire & Black Ground wire. Red wire on 1 ESC used, rest are removed and taped off. Reading Pixhawk wiring diagram says to use PPM convertor-between RC-Receiver & Pixhawk FC w/1-3 wire cable. Unable to find PPM Convertor…! PWM is so old, why doesn’t Pixhawk Firmware go to PPM…? Also does Pixhawk support SBUS and/or IBUS… for PWM or PPM…? ESC’s do calibrate in QGC Pixhawk never ARM’s Full Green LED on Pixhawk, GPS LOCKed 16 Satellites, Push Safety Switch, beeps, no ARM…! No Throttle or other controls on sticks, no launch, no nothing…! My conclusion Pixhawk made in China, piece of junk…! Or, ESC’s need to be flashed w/updated Firmware…can’t find devices to flash Firmware… Tired of buying China junk… I got $100.00 in batteries and $100.00 in Motors, nothing works…! Something is not right…my mistake…? Who knows…? Others have built this same S500mm Quad w/no problems, I got wrong parts…? So possibly two problems or more, ESC’s and/or PWM/PPM connections incorrect…? Thanks in Advance…! Frustrated Me…! =)

Sorry, I forgot something… QGC is Running on Dell Inspiron 15 3000 Series w/ MX-19 Linux OS 64 bit… Batteries: 2- 4S Li-Po 5000mAh 50C 14.8 VDC.

If the receiver is PPM you can connect it straight into a Pixhawk and it should work. The output to the ESCs is then usually PWM.

Things to check if nothing is spinning that come to mind:

  1. Have you done the RC calibration?
  2. Have you done the ESC calibration?

Have you seen these guides here?

Thanks for the quick reply…! According to the “Flysky” Documents for the RC-Receiver it uses iBUS as output, not sBUS. RC Transmitter, set RX-Receiver Output PPM-iBUS. One twisted cable 3-wire(Red, Black, White) from RC-Receiver to Pixhawk-RC-IN.
Yes, I have gone through all Calibrations in QGC, including RC Calibration and ESC Calibration. I have seen/read tons of doc’s on Pixhawk…could never determine if the Pixhawk would accept PPM input from RC-Receiver, all they said was, if RC-Receiver output was PWM or PPM-SUM you need a PPM Convertor to convert PWM to PPM. But it never said if RC-Receiver output is PPM… Some how, I got locked into that expression and then I got confused on the use of sBUS and iBUS…! So, on the Pixhawk 1, old style case, (all the pins out) I have manufacturer label on case: AUX-OUT: Pins 1 thru 6, MAIN-OUT: Pins 1 thru 8, next is: SBUS, then RC-In. Since SBUS and IBUS are similar, do I use SBUS as IBUS, or do I change RC-Transmitter setting to PPM, SBUS…? Because I don’t have a rail Marked: Ibus…? The “Flysky” Receiver that came w/the “Flysky” Transmitter does have different Rail Markings as follows:
IBUS - 2 sections: SENSOR & SERVOS each separate section has 3 Pin’s in Horizontal array. At the end of the SERVO section there is label “PPM/CH1”. A larger section below all that is 7 Rows of 3-pins in Vertical array, I think these represent the Channels 1 thru 6 (since its a 6 channel Receiver) plus 1-set of 3-Pins for B/VCC.
See this link for Photo and description:

FS IA6b I connected the receiver with ppm to pixhawk 2.4.8. But it’s not working. What is the problem?