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S Y S T E M C O N T R O L M O D U L E
Enhanced PWM function
www.digiembedded.com
145
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E n h a n c e d P W M f u n c t i o n
Timer counters 6–9 have additional features to add enhanced PWM functionality:
High register — Compared to the timer/counter to toggle PWM output high
Low register — Compared to the timer/counter to toggle PWM output back low
Three 15-bit Step registers associated with four enhanced timer/counters. The
values of Step registers are added when the high, low, and reload values are
reached, which allows a steadily variable motor control PWM wave to be
generated. The enhanced PWM function is output through GPIO through the
functions labeled Ext Timer Event Out Ch N for channels 6 to 9.
Sample enhanced
PWM waveform
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Q u a d r a t u r e d e c o d e r f u n c t i o n
The processor provides a quadrature decoder function to allow the CPU to
determine the external device rate of rotation and the direction of rotation.
Example applications are robotic axles for feedback control, mechanical knobs to
determine user input, and in computer mice, to determine direction of movement.
One timer/counter will include a quadrature decoder function, which takes some
computational load off the CPU. When a CPU reads the output signals of a
quadrature encoder, every state must be decoded and a counter needs to be
updated based on the interpretation of the states. For example, for an encoder of
256 pulses per revolution turning at a modest 6000 rpm, the CPU needs to find and
decoded 102,400 state changes per second and update the counter accordingly.
With an x8 sampling rate, the CPU needs to sample the input about 8 x 102,400
timer per second. This consumes a significant portion of the CPU bandwidth.
Timer Counter clock frequency
PWM period
Low time 1
High time
Low time 2
75MHz
873.000 usec
382.293 usec
218.453 usec
272.254 usec
Reload Value
FFFF_0000
High Value
FFFF_7000
High Value
FFFF_B000
Terminal Count
FFFF_FFFF
Содержание NS9215
Страница 1: ...NS9215 Hardware Reference 90000847_C Release date 10 April 2008...
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Страница 26: ...26 Hardware Reference NS9215...
Страница 44: ...P I N O U T 26 5 System clock 44 Hardware Reference NS9215 System clock drawing...
Страница 52: ...P I N O U T 26 5 Power and ground 52 Hardware Reference NS9215...
Страница 80: ...I O C O N T ROL M O D U L E Memory Bus Configuration register 80 Hardware Reference NS9215...
Страница 136: ...WOR KI N G W I TH T H E C P U Noncachable instruction fetches 136 Hardware Reference NS9215...
Страница 202: ...S Y S T E M C O N T RO L M OD U L E RTC Module Control register 202 Hardware Reference NS9215...
Страница 260: ...M E MO R Y C O N T ROL L E R StaticMemory Turn Round Delay 0 3 registers 260 Hardware Reference NS9215...
Страница 354: ...E X T E R N A L D M A DMA Peripheral Chip Select register 354 Hardware Reference NS9215...
Страница 362: ...A E S D AT A E N C R Y P T I O N D E C R Y P T I O N M O D U L E CCM mode 362 Hardware Reference NS9215...
Страница 384: ...I O HU B M OD UL E Module Direct Mode TX Data Last FIFO 384 Hardware Reference NS9215 31 March 2008...
Страница 414: ...S E R I A L C ON T RO L M O D U L E U ART UART Modem Status register 414 Hardware Reference NS9215...
Страница 446: ...S E R I A L C ON T RO L M O D U L E S PI SPI timing characteristics 446 Hardware Reference NS9215...
Страница 472: ...R E A L TI M E C L O C K M O D U L E General Status register 472 Hardware Reference NS9215...
Страница 512: ...TI M I NG Clock timing 512 Hardware Reference NS9215...
Страница 514: ...PA CKA GING Processor Dimensions 514 Hardware Reference NS9215 P r o c e s s o r D i m e n s i o n s...
Страница 515: ...PA CKA GING Processor Dimensions www digiembedded com 515...
Страница 516: ...PA CKA GING Processor Dimensions 516 Hardware Reference NS9215...