Intel PXA26X User Manual download pdf (Page 153)

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Intel® PXA26x Processor Family Developer’s Manual 4-45

System Integration Unit

4.5.2.1 PWM Control Registers (PWM_CTRLn)

The PWMn Control Register, PWM_CTRLn, contains two fields:

• PRESCALE – The PRESCALE field contains the 6-bit prescale counter load value. This field

allows the 3.6864-MHz-input clock PSCLK_PWMn, to be divided by values between 1

(PWM_CTL[PRESCALE] = 0) and 64 (PWM_CTL[PRESCALE] = 63).

Note: The value of the divisor is one greater than the value programmed into the PRESCALE field.

• PWM_SD – PWMn can shut down in one of two ways, gracefully or abruptly, depending on

the setting of PWM_CTRLn[PWM_SD]. If gracefully is chosen, then the duty cycle counter

completes its count before PWMn is shut down. If abruptly is chosen, then the prescale

counter and the duty cycle counter are reset to the reload values in their associated registers

and PWMn is immediately shut down.

Note: During abrupt shut down the PWM_OUTn signal may be delayed by up to one PSCLK_PWMn

clock period.

Table 4-50 shows the bitmap of the PWM Control registers.

4.5.2.2 PWM Duty Cycle Registers (PWM_DUTYn)

The PWM Duty Cycle register, PWM_DUTYn, contains two fields:

• FDCYCLE

• DCYCLE

Table 4-50. PWM_CTRLn Bit Definitions

Physical Address

0x40B0_0000

0x40C0_0000

PWM Control Registers

(PWM_CTRL0, PWM_CTRL1)

System Integration Unit

Bit

31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0

Reserved

PWM_SD

PRESCALE

Reset

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Bits Name Description

<31:7> — Reserved

<6> PWM_SD

PWMn SHUTDOWN METHOD:

0 – Graceful shutdown of PWMn when the clock enable bit in the CKEN register is

cleared.

1 – Abrupt shutdown of PWMn when the clock enable bit in the CKEN register is cleared.

<5:0> PRESCALE

PWMn PRESCALE DIVISOR:

Determines the frequency of the PWM module clock (in terms of the 3.86-MHz clock)

PSCLK_PWMn = 3.6864 MHz / (PWM_CTRL[PRESCALE] + 1)

1 2 ... 148 149 150 151 152 153 154 155 156 157 158 ... 623 624

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Intel PXA26X User Manual Page 153

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