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Texas Instruments MSC1210 User Manual

Page 128

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Tone Generator

11-4

11.2.1 Tone Generator Waveforms

When TPCNTL[1:0] = 11, the output of the tone generator may be either a stair-
case waveform or a square waveform depending on the configuration of
TPCNTL.2.

When TPCNTL.2 is 1, a staircase waveform is generated that will have three
levels: DGND, tristate, and V

DD

volts.

When the TPCNTL.2 is 0, a square waveform of 50% duty cycle is generated
that will have two levels: DGND and V

DD

volts.

11.2.1.1 Staircase Mode

When TPCNTL.2 is 1 (i.e., TPCNTL[2:0] = 111), a staircase waveform is gener-
ated, as shown in Figure 11−3. In this figure, the value of PWM Period = 18F

H

,

which is equal to 399. Therefore, the total time period is equal to 800 T

BASE

.

11.2.1.2 Square Mode

When TPCNTL.2 is ‘0’ (i.e., TPCNTL[2:0] = ‘011’), a square waveform is gen-
erated. An example with PWM Period = 2 is shown in Figure 11−4. We get a
50 % duty cycle square wave with a period of (2

S

PWM Period).

Figure 11−3. Timing Diagram of Tone Generator in Staircase Mode

Figure 11−4. Timing Diagram of Tone Generator in Square Wave Mode