PWM stands for Pulse Width Modulation. Most modern power control is done using mosfets, which are high speed switches. PWM is a method for varying the output power by switching the output to full power for a very short period and then off. This is performed over and over at high frequency, usually from about 1 kHz (1000 times per second) up to around 100 kHz (100,000 time per second). The power is varied by changing the ratio of on time to off time.

PWM stands for Pulse Width Modulation. The speed controller uses PWM to control the power going to the motor. The controller breaks the current going to the motor into separate pulses that occur about 13,000 times per second. The percentage of the pulse that is on power compared to the part of the pulse that is off power determines how much power the motor sees. An oversimplified example is that if 50% of the pulse is on and 50% is off, the motor sees 50% power.

PWM stands for Pulse Width Modulation. It is a method for applying a variable amount of power by changing the on and off time of a periodic signal. For example, an output that is fully on 50% of the time, and fully off the other 50% this will average in an actual average power to the motor of 50%. For PWM to work well, however, the on-off cycle must repeat at a relatively high frequency.

Roboteq's controller PWM frequency is 16 kHz This means that the variable on-off cycle will repeat every 64 microseconds. 16 kHz is a high frequency value for PWM control that will result in smoother and more energy efficient motor operation than at lower frequencies. The use of high PWM frequency will also result in silent motor operation.

In the AX2550, the PWM cycle is divided into 128 steps. Other than always on and always off, the AX2550 can generate any ratio ranging from 1/128th to 127/128th. Another way to put it is that the controller output can range fro 0% power to 100% power in 128 steps of 0.8%. This is a very fine level of control by any practical measure.

The PWM has a period of 100?s that makes a frequency of 10kHz. The conroller runs with 8MHz. 100?s makes it all very easy: the rc-puls from 1100?s to 1900?s is evaluated and the range (800) than shifted right 3 times means divided by 8 - makes 100 and is directly used for PWM. Timer0 is set to 1?s and has only to generate the PWM and to evaluate the PWM state.

For PWM (6+2) mode, the PWM cycle is divided into 4 modulation cycles. Each modulation cycle has 64 PWM input clock periods, and the PWM frequency will be fSYS/26. For PWM (7+1) mode, the PWM cycle is divided into 2 modulation cycles. Each modulation cycle has 128 PWM input clock periods, and the PWM frequency will be fSYS/27. In comparison with the 8-bit mode, the (6+2) Mode PWM frequency is 4 times higher and (7+1) mode is 2 times higher than that of the 8-bit mode.

For HT46 series MCUs, the PWM frequency is derived by calculating fsys/256, in other words, once the system clock is selected, the PWM frequency is therefore fixed. Users can only adjust the PWM duty through the PWM register.