Texas Instruments MSC1210 - Manual (Page 133)

PWM Generator
11-9
Pulse Width Modulator/Tone Generator
11.3.2 Example of PWM Tone Generation Idling
When PWM is idling, system requirements for the PWM output varies (idle at
low or high voltage). The output of P3.3 (Tone/PWM) is internal pull-high upon
power-on reset—idle high. If idle low is needed, many methods can be used
to initialize P3.3 to low.
Note:
If idle low on Tone/PWM is achieved by writing 0 to P3.3 (which will suppress
PWM output), subsequently, writing a 1 to P3.3 will enable PWM output at
any position of the PWM cycle.
The following program, shown in Table 11−4, is very similar to the one provided
in the previous section. PWM Duty is initially set to zero, which idles the PWM.
It is then reset to 4, at which point the function of the program continues as the
program above. Table 11−5 explains selected statements.