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CHAPTER 13 16-Bit I/O TIMER
13.6 Explanation of Operation of Input Capture
The input capture stores the counter value of the 16-bit free-run timer to the input
capture register at the timing that is detected the input signal of the valid edge from the
external input pin or that the trigger edge for the LIN slave baud rate measurement is
inputted, the interrupt request is generated.
■ Setting of Input Capture
Operation of the input capture requires the setting shown in Figure 13.6-1
Figure 13.6-1 Setting of Input Capture
[Input capture operation]
The following operation is executed when the set valid edge (ICS:EG) is detected in the input capture pin,
or when the trigger edge for the LIN slave baud rate measurement from the LIN-UART is inputted.
• The counter value of the 16-bit free-run timer to time detected is stored in the input capture register.
• The detected edge direction is stored to the detection edge indication bit. (rising:IEI=1, falling:IEI=0)
• The valid edge detection flag of the input capture control status register is set to "1". (ICS:ICP=1)
• When the input capture interrupt request is enabled (ICS:ICE=1), the interrupt request is generated.
• To measure the baud rate at the LIN slave operation, it is necessary to set the input signal to the LIN-
UART (ICE:ICUS), enable the input capture interrupt request (ICS:ICE=1), and set the valid edge to
both edges (ICE:EG1, EG0=11
B
). See "20.7.3 Operation with LIN Function (Operation Mode 3)" for
the calculation of the baud rate.
Figure 13.6-2 shows the timing of fetching a data for the input capture. Figure 13.6-3 shows the operation
when valid edge is set to the rising edge/falling edge. Figure 13.6-4 shows the operation when valid edge is
set to both edges.
ICEn
EGm1 EGn1 EGn0EGm0
ICPnICPm
ICEm
IPCP
ICE/ICS
bit15 14 13 12 11 10 9 bit8 bit7 654321bit0
IEIm IEIn
❍
: Using bit (Set the bit corresponding to used channel)
▲
: Using bit (Exist only ICE01’s bit, Set the bit at measurement LIN slave baud rate
Hold counter value of input capture
Setting the corresponding bit using pin as
capture input pin to "0".
DDR port
direction
register
n = 0, 2 m = n + 1
✕
✕
✕▲
▲
▲❍
❍
❍
❍❍ ❍❍
❍❍❍