UPDATE:
Some other projects required my immidiate attention, but it is all sorted now and I now have a chance to continue here.
My なぜ32 boards arrived a few weeks ago, and almost managed to brick one of them with some custom firmware - remember to backup your ROMs people!
Edit: I dont know how to resize photos in posts anymore - did someone at mybb change the settings
?
Here's a picture of soldering the pins:
And the finished product:
(Yes, that is a Raspberry Pi 3... yes it will be doing the FPV and drone management....)
As a quick intro to PWM:
Pulse Width Modulation is a method of DC switching as either a control signal, or as a method of DC-DC voltage step-down. It is simply switching a DC voltage supply on and off very quickly. The length of time between the start of one on cycle and the start of the next is known as the period of the cycle (its inverse the frequncy). The percentage of time that the switch is on during a single cycle is known as the Duty Cycle, often known as the DC of a PWM (yes I know, it is easy to confuse with Direct current, but PWM is normally assumed to be a Direct Current power source/signal anyway).
Using PWM as a DC-DC voltage step down method is quite straightforward. If the DC is 50% (DC in this case being duty-cycle... see what I mean yet about these silly acronyms?) and the switching is of a high enough frequency, the output voltage of the PWM switch is effectively half of the input. There are lots of youtube videos where you can see people using Pi*s (Pies?) with PWM on the GPIO pins to effectively dim an LED. Same story for DC motors - if you feed the motor with a high current PWM supply, you can effectively control the power output of the motor by controlling the DC of the PWM.
This is exactly what an ESC does (except it usually outputs a three-phase current supply - don't worry if you dont understand, it isnt too important for our purposes). An ESC, or Electronic Speed Controller, is a special circuit that controlls a single BLDC motor, or Brushless Direct Current motor. (I won't go into detail why BLDCs are waaaaay more useful than the classical brushed DC motors that you learn about it High-school Science - what is really important is that they are super efficient and have very high power-densities; perfect for remote controlled aircraft. You're welcome to wiki and youtube BLDCs and ESCs if you are interested in the
why 
).
PWM can also be used as an analogue signal method. For example, you could have the DC of a PWM represent an anologue message of percentage. If you send a DC of say .4, the message could be "40" that you are attempting to send. In the real world, we leave padding on both sides (control theory - again not too important for our purposes here) such that a DC of 0.25 represents a "0" and a DC of .75 represents "100" and anything inbetween is just the linear fraction thereof.
Unfortunately there is no global standardization authority dealing specifically with PWM, especially as a signal method. Every manufacturor and Engineer normally just uses something that is sensible for the specific task at hand. As you have probably guessed, this can lead to definate incompatabilities between different systems. Luckily since remote controlled aircraft have been around for a while, there are more or less rules of thumb that different manufacturors have tended to stick to over the past couple years. IMPORTANT: These are
rules of thumb and
not rules. Servo motors are one type of device that have used PWM for remote controlled aircraft since more or less the beginning of the hobby. The servos can be attached directly to rods that actuate ailerons and flaps etc. for planes and flying wings. Servos usually follow the rules of thumb for Position Pulse Modulation (PPM) over PWM (again, this isn't too important for us): The "normal" PWM signalling frequency is 50Hz and a pulse of 1ms (DC = 0.05) corrisponds to a "0" or "minimum" and a pulse of 2ms (DC = 0.1) corrisponds to a "100" or maximum. Most servos go from 0 to 180 degrees, and will attempt to actuate their angle of rotation to match that of the signal you feed it.
Here's a picture from wiki:
ESCs
usually operate in exactly the same manner as servos such that you can signal it to control the output power a BLDC using the DC of a PWM signal. Of course different ESCs will have different methods of communications and protocols (fancy new ESCs dont even bother with an analogue signal from a controller and instead operate over a serial communications interface - which may even be a two-way communication! Imagine all the metadata you can collect with that...), but the 1ms pulse for "0" and 2ms pulse for "100" is more or less standard.
Having fun yet
?
Next time: Methods of comms with the drone's controller. Did you say you like PWMs? Well there is plenty more of that!
What's the diffs between the Tx and the Rx cloverleaf antennas other than the printed outside - do they really differ in functional terms?
Also, what about autonomous flight - is the controller capable?
Yes, the Rx and Tx antennas have different number of lobes. The Rx usually has 3, the Tx has 4. I won't go into details but that way it is better optimised to give you better range. You can however use a Tx as an Rx and the other way round - wont make much of a difference but will probably hurt your range a bit.
