eCAP
7 - 38
C2000 Microcontroller Workshop - Control Peripherals
Some Uses for the Capture Module
Problem:
At low speeds, calculation of speed
based on a measured position change at
fixed time intervals produces large estimate
errors
Alternative:
Estimate the speed using a measured time interval
at fixed position intervals
Signal from one
quadrature
encoder channel
Low speed velocity estimation from incr. encoder:
Measure the time width of a pulse
v
k
≈
∆
x
t
k
- t
k-1
v
k
≈
∆
t
x
k
- x
k-1
∆
x
Auxiliary PWM generation
eCAP Module Block Diagram
– Capture Mode
32-Bit
Time-Stamp
Counter
Capture 1
Register
Event
Prescale
Polarity
Select 1
Polarity
Select 2
Polarity
Select 3
Polarity
Select 4
Capture 2
Register
Capture 3
Register
Capture 4
Register
E
v
e
n
t L
o
g
ic
ECAPx
pin
SYSCLKOUT
CAP1POL
CAP2POL
CAP3POL
CAP4POL
PRESCALE
The capture module features a 32-bit time-stamp counter to minimize rollover. Each module has
four capture registers. Polarity can be set to trigger on rising or falling edge, and trigger events
Содержание C2000 Piccolo LaunchPad
Страница 74: ...Interrupts 4 18 C2000 Microcontroller Workshop Reset and Interrupts ...
Страница 100: ...Lab 5 System Initialization 5 26 C2000 Microcontroller Workshop System Initialization ...
Страница 126: ...Lab 6 Analog to Digital Converter 6 26 C2000 Microcontroller Workshop Analog to Digital Converter ...
Страница 218: ...Lab 8 IQmath FIR Filter 8 42 C2000 Microcontroller Workshop Numerical Concepts ...
Страница 236: ...Lab 9 Servicing the ADC with DMA 9 18 C2000 Microcontroller Workshop Direct Memory Access Controller ...
Страница 260: ...Lab 10 CLA Floating Point FIR Filter 10 24 C2000 Microcontroller Workshop Control Law Accelerator ...
Страница 331: ...C2000 Microcontroller Workshop Appendix A Experimenter s Kit A 1 Appendix A Experimenter s Kit ...
Страница 334: ...F28069 controlCARD A 4 C2000 Microcontroller Workshop Appendix A Experimenter s Kit SW2 ...
Страница 336: ...F28035 controlCARD A 6 C2000 Microcontroller Workshop Appendix A Experimenter s Kit SW2 SW3 ...
Страница 338: ...F28335 controlCARD A 8 C2000 Microcontroller Workshop Appendix A Experimenter s Kit LD1 LD2 LD3 SW1 ...