NXP Semiconductors PXN2020, Reference Manual, Page: 845 / 1376

Enhanced Modular Input/Output Subsystem (eMIOS200)
PXN20 Microcontroller Reference Manual, Rev. 1
Freescale Semiconductor 28-23
In GPIO input mode (MODE = 000_0000),the FLAG generation is determined according to EDPOL and
EDSEL bits and the input pin status can be determined by reading the UCIN bit.
In GPIO output mode (MODE = 000_0001), the unified channel is used as a single output port pin and the
value of the EDPOL bit is permanently transferred to the output flip-flop.
28.4.1.1.2 Single Action Input Capture (SAIC) Mode
In SAIC mode (MODE = 000_0010), when a triggering event occurs on the input pin, the value on the
selected time base is captured into register A2. At the same time, the FLAG bit is set to indicate that an
input capture has occurred. Register EMIOS_CADR[
n ] returns the value of register A2. The channel is
ready to capture events as soon as SAIC mode is entered coming out from GPIO mode. The events are
captured as soon as they occur, thus reading register A always returns the value of the latest captured event.
Subsequent captures are enabled with no need of further reads from EMIOS_CADR[
n ] register. The
FLAG is set at any time a new event is captured.
The input capture is triggered by a rising, falling or either edges in the input pin, as configured by EDPOL
and EDSEL bits in EMIOS_CCR[
n ] register.
Figure 28-15 and Figure 28-16 show how the unified channel can be used for input capture.
Figure 28-15. Single Action Input Capture with Rising Edge Triggering Example
Selected
Counter Bus
FLAG
Set Event
Edge detect Edge detect Edge detect
A2 (Captured)
Value
2
0xxxxxxx 0x001000 0x001250 0x0016A0
Notes:
1
2
Input Signal
1
0x000500 0x001000 0x001100 0x001250 0x001525 0x0016A0
After input filter
EMIOS_CADR[n]

A2