Datasheet

F28M36P63C, F28M36P53C, F28M36H53C, F28M36H53B, F28M36H33C, F28M36H33B
SPRS825C –OCTOBER 2012–REVISED FEBRUARY 2014 www.ti.com
7.3.2 Enhanced Capture Module
There are six identical eCAP modules in Concerto devices: eCAP1, 2, 3, 4, 5, and 6. Each eCAP module
represents one complete capture channel. Its main function is to accurately capture the timings of external
events. One can also use eCAP modules for PWM, when they are not being used for input captures. This
secondary function is selected by flipping the CAP/APWM bit of the ECCTL2 Register. For PWM function,
the counter operates in count-up mode, providing a time base for asymmetrical pulse width (PWM)
waveforms. The CAP1 and CAP2 registers become the period and compare registers, respectively; while
the CAP3 and CAP4 registers become the shadow registers of the main period and capture registers,
respectively.
The left side of Figure 7-37 shows internal components associated with the capture block, and the right
side depicts the PWM block. The two blocks share a set of four registers that are used in both Capture
and PWM modes. Other components include the Counter block that uses the SYNCIN and SYNCOUT
ports to synchronize with other modules; and the Interrupt Trigger and Flag Control block that sends
Capture, PWM, and Counter events to the C28x PIE block via the ECAPxINT output. There are six
ECAPxINT interrupts—one for each eCAP module.
The eCAP peripherals are clocked by C28SYSCLK, and its registers are accessible by the C28x CPU.
This peripheral clock can be enabled or disabled by flipping a bit in one of the system control registers.
7.3.2.1 eCAP Electrical Data and Timing
Table 7-35 shows the eCAP timing requirement and Table 7-36 shows the eCAP switching characteristics.
Table 7-35. eCAP Timing Requirement
(1)
MIN MAX UNIT
t
w(CAP)
Capture input pulse width Asynchronous 2t
c(SCO)
cycles
Synchronous 2t
c(SCO)
cycles
With input qualifier 1t
c(SCO)
+ t
w(IQSW)
cycles
(1) For an explanation of the input qualifier parameters, see Table 6-33.
Table 7-36. eCAP Switching Characteristics
over recommended operating conditions (unless otherwise noted)
PARAMETER TEST CONDITIONS MIN MAX UNIT
t
w(APWM)
Pulse duration, APWMx output high/low 20 ns
216 Peripheral Information and Timings Copyright © 2012–2014, Texas Instruments Incorporated
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