19/21

16-BIT TIMING OPERATIONS USING ST7262 OR ST7263B MCUs

Figure 17. Without Optimization

Using the optimization method we will generate only 04 waves (period = FFh) then two

additional waves with a period of 82h (Figure 18) which provide the necessary delay for the

interrupt routine.

Figure 18. With Optimization

2.2 USING ST7263B

2.2.1 Principles

The Pulse Width Modulation (PWM) mode in the ST7263B, enables the generation of a PWM

signal with a frequency and pulse length controlled by the value of the OC1R and OC2R reg-

isters. To use Pulse Width Modulation mode we have to follow the steps described below:

Step 1. Load the OC2R register with the value corresponding to the period of the signal using

the following formula

With:

t = Signal or pulse period (in seconds)

Prescaler = Timer prescaler factor

Step 2. Load the OC1R register with the value corresponding to the period of the pulse using

the same formula as above.

Step 3. Configure CR1 register:

– Using the OLVL1 bit, select the level to be applied to the OCMP1 pin after a successful com-

parison with OC1R register.

1

23

45

The last PWM wave period is too small (04 Ttimer )

to be generated

5 PWM waves with a period of FFh

1

23

4

Two PWM waves with period (82h *Ttimer )

4 PWM waves with a period of FFh

1

2

OCiR

t Fcpu

×

() Prescaler

()

⁄

5

–

=