Code 42

Note: It's been about 2 months since I've posted the part 3 of this article. Sorry for being late with this part. I hope you have read my earlier articles on Li-Po batteries (Li-Po Batteries Explained Part 1 , Part 2 and Part 3 ). Now let's look at the most important part - charging and maintenance. First of all, why is this so important? Well, just watch the following video on what happens when you mistreat a Li-Po battery. So....., now that you've seen the dangers of Li-Po batteries, it should be clear that they should be handled with care. Li-Po's are very different from conventional rechargeable batteries, so you should only use a charger specifically designed for Li-Po's. Doing so will increase the life span of the Li-Po battery pack and yours as well.

If you have studied about brushless motors, you'll probably know that they need a electronic controller (ESC) to run. Since the ESC can't actually see how the motor is running,  it needs to somehow detect the orientation of the rotor (moving part) relative to the stator (stationary part) of the motor. The two most popular ways of doing this is to use a Hall Effect Sensor or to measure the Back EMF of the undriven coils. The Back EMF method does not require any additional sensors, but it's implementation is complicated and has to overcome several issues. The Hall Effect method is much simpler than that, but requires a Hall Effect Sensor near the rotor of the motor to operate. So, how does a Hall Effect sensor work? Simply put, it is a device that varies its output voltage based on changes on a magnetic field. The operation of the sensor is based on the Hall Effect which was discovered by Edwin Hall in 1879. The theory is explained as follows,  The Hall Effect

If you go shopping for Brushless motors you will be confronted with a lot of numbers to choose. For an example, you would see motors marked with 3632 22turn 1500Kv, 2213 20turn 920Kv etc. So what does all those numbers mean, and how would you choose? Here's a simple guide... Let's take this motor for an example, Turnigy 2213 20turn 1050Kv Outrunner It's marked as "2213 20turn 1050Kv Outrunner". Let's see what it means. First of all, it's clearly written that this is an Outrunner motor. The "2213" indicates the size of the stator, First two numbers = diameter of the stator = 22mm Second two numbers = length of the stator stack = 13mm

Using a popular PIC microcontroller such as the 16F877A and a high level compiler such as mikroC, you can do a lot of things. In the last post I discussed about how to get a PWM signal based on an analog signal. Now let's try to do extend that and try to get 2 PWM signals from the same PIC chip. Why would you need 2 PWM signals? Let's say you are building a robot, and you have 2 motors that need to work independently. Or 2 servos you need to control separately etc. As you know, the CCP (Capture/Compare/PWM) module in a microcontroller is responsible for generating PWM signals. So, to get 2 separate PWM signals, you need a microcontroller with 2 CCP modules. If we look at the datasheet ( link ) of the 16F877A, we can see that it has 2 CCP modules (PIC16F87XA Datasheet - Section 8). So, now let's get our PWM signals... However, there's one thing you have to know when you use the 2 CCP modules together. If you look at Table 8-2 from the datasheet, when you configure...