MOTOROLA
Pulse-Width Modulator (PWM)
22-1
Chapter 22
Pulse-Width Modulator (PWM)
The pulse-width modulator (PWM) of the MC9328MX1 is optimized to use 16-bit resolution and a 4
×
16
data FIFO to generate high quality sound from stored audio files and to generate tones. Figure 22-1
illustrates the block diagram of the pulse-width modulator.
Figure 22-1. Pulse-Width Modulator Block Diagram
22.1 Introduction
The PWM can be programmed to select one of two clock signals as its source frequency. The selected
clock signal is passed through a divider and a prescaler before being input to the counter. The output is
available at the pulse-width modulator output (PWMO) external pin.
22.2 PWM Signals
22.2.1 Clock Signals
As shown in Figure 22-1, the clock source (CLKSRC) bit in the PWM control (PWMC) register selects the
source clock—PERCLK1 (the default) or CLK32—to be used by the PWM. The selected clock signal is
then sent through a divider and a prescaler to produce the PCLK signal.
The clock selection (CLKSEL) field in the PWMC selects the frequency of the output of the divider chain.
The incoming clock source is divided by a binary value between 2 and 16.
For 16 kHz audio applications, CLKSEL = 01, divide by 4. For DC-level applications, CLKSEL = 11,
divide by 16. See Table 22-7 on page 22-8 for a complete list of settings for the PWMC register.
PCLK
Sample Compare
PWMO
Output
Control
Prescaler
Counter
PERCLK1
4-Word FIFO
MPU Interface
Divider
CLK32
Period
CLKSRC
Summary of Contents for DragonBall MC9328MX1
Page 68: ...1 12 MC9328MX1 Reference Manual MOTOROLA Introduction ...
Page 86: ...2 18 MC9328MX1 Reference Manual MOTOROLA Signal Descriptions and Pin Assignments ...
Page 116: ...3 30 MC9328MX1 Reference Manual MOTOROLA Memory Map ...
Page 126: ...4 10 MC9328MX1 Reference Manual MOTOROLA ARM920T Processor ...
Page 160: ...8 8 MC9328MX1 Reference Manual MOTOROLA System Control ...
Page 272: ...13 32 MC9328MX1 Reference Manual MOTOROLA DMA Controller ...
Page 281: ...Programming Model MOTOROLA Watchdog Timer Module 14 9 ...
Page 282: ...14 10 MC9328MX1 Reference Manual MOTOROLA Watchdog Timer Module ...
Page 300: ...15 18 MC9328MX1 Reference Manual MOTOROLA Analog Signal Processor ASP ...
Page 438: ...18 16 MC9328MX1 Reference Manual MOTOROLA Serial Peripheral Interface Modules SPI 1 and SPI 2 ...
Page 478: ...19 40 MC9328MX1 Reference Manual MOTOROLA LCD Controller ...
Page 574: ...21 32 MC9328MX1 Reference Manual MOTOROLA Memory Stick Host Controller MSHC Module ...
Page 598: ...23 16 MC9328MX1 Reference Manual MOTOROLA Real Time Clock RTC ...
Page 670: ...24 72 MC9328MX1 Reference Manual MOTOROLA SDRAM Memory Controller ...
Page 726: ...25 56 MC9328MX1 Reference Manual MOTOROLA SmartCard Interface Module SIM ...
Page 736: ...26 10 MC9328MX1 Reference Manual MOTOROLA General Purpose Timers ...
Page 854: ...29 18 MC9328MX1 Reference Manual MOTOROLA I2C Module ...
Page 900: ...30 46 MC9328MX1 Reference Manual MOTOROLA Synchronous Serial Interface SSI ...
Page 942: ...32 26 MC9328MX1 Reference Manual MOTOROLA GPIO Module and I O Multiplexer IOMUX ...