4-46 Intel® PXA26x Processor Family Developer’s Manual
System Integration Unit
The FDCYCLE bit determines whether or not PWM_OUTn is a function of the DCYCLE bits in
the PWM_DUTYn register or is set high. When the FDCYCLE bit is cleared low (normal
operation), the output waveform of PWM_OUTn is cyclic, with PWM_OUTn being high for the
number of PSCLK_PWMn periods equal to DCYCLE.
If FDCYCLE = 0x0 and DCYCLE = 0x0, PWM_OUTn is set low and does not togg le.
Note: If FDCYCLE is 0b1, PWM_OUTn is high for the entire period and is not influenced by the value
programmed in the DCYCLE bits.
Table 4 -51 shows the bitmap of the PWM Duty registers.
4.5.2.3 PWM Period Control Register (PWM_PERVALn)
The PWM Period Control register (PWM_PERVALn) contains a 10 bit field called PV. This field
determines the period of the PWM_OUTn waveform in terms of the PSCLK_PWMn clock. If this
field is cleared to zero PWMn is effectively turned off and PWM_OUTn remains in a high state.
For any non-zero valu e written to the PV fi eld, the output freque ncy of PWMn is the freq uency of
the PSCLK_OUTn divided by the value of (PV + 1). The range of the clock gate extends from a
pass-through of the PSCLK_PWMn to a clock delay of 26 or 64 input clocks per output pulse.
When the value of the 10 bit up-counter equals the value of (PV +1), the up-cou nter and the flip-
flop are reset and the values of PWM_CTRLn, PWM_PERVALn and PWM_DUTYn are loaded
into the internal versions of these registers. Resetting this flip-f lop causes PWM_OUTn to go low
and the PWM cycle to start again.
Writing all zeroes to this register results in the output maintaining a high state unless
FDCYCLE= 0x0 and DCYCLE = 0x0. If FDCYCLE = 0x0 and DCYCLE= 0x0, the output
maintains a low state regardless of the value in the PV bit field.
Table 4-51. PWM_DUTYn Bit Definitions
Physical Address
0x40B0_0004
0x40C0_0004
PWM Duty Cycle Registers
(PWM_DUTY0, PWM_DUTY1) 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
FDCYCLE
DCYCLE
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
<31:11> — Reserved
<10> FDCYCLE
PWMn FULL DUTY CYCLE:
0 – PWM clock (PWM_OUTn) duty cycle is determined by DCYCLE field.
1 – PWM_OUTn is set high and does not toggle.
<9:0> DCYCLE PWMn DUTY CYCLE:
Duty cycle of PWMn clock, i.e. the number of PSCLK_PWM cycles PWMn is asserted
within one cycle of PWMn.