11.12 Operation Of Input Capture Function - Fujitsu 8FX Hardware Manual

CHAPTER 11 8/16-BIT COMPOSITE TIMER

11.12 Operation of Input Capture Function

11.12 Operation of Input Capture Function
This section describes the operation of the input capture function of the 8/16-
bit composite timer.
■ Operation of Input Capture Function
To use the input capture function, do the settings shown in Figure 11.12-1.
Tn0CR0/Tn1CR0
Tn0CR1/Tn1CR1
TMCRn
Tn0DR/Tn1DR
When the input capture function is selected, the counter value is stored to the 8/16-bit
composite timer data register (Tn0DR/Tn1DR) immediately after an edge of the external signal
input is detected. The target edge to be detected is selected by the timer operating mode select
bits (Tn0CR0/Tn1CR0:F[3:0]).
This function is available in free-run mode and clear mode, which can be selected by the timer
operating mode select bits.
In clear mode, the counter starts counting from "0x00". When an edge is detected, the counter
value is transferred to the 8/16-bit composite timer data register (Tn0DR/Tn1DR), the interrupt
flag (Tn0CR1/Tn1CR1:IR) is set to "1", and the counter returns to "0x00" and restarts
counting.
In free-run mode, when an edge is detected, the counter value is transferred to the 8/16-bit
composite timer data register (Tn0DR/Tn1DR) and the interrupt flag (Tn0CR1/Tn1CR1:IR) is
set to "1". In this case, the counter continues to count without being cleared.
This function has no effect on the buffer full flag (Tn0CR1/Tn1CR1:BF).
The time exceeding the range of the counter can be measured by counting the number of
counter overflows using the software. When the counter overflows, the interrupt flag (Tn0CR1/
Tn1CR1:IF) is set to "1". The interrupt service routine can therefore be used to count the
number of overflows. In addition, the timer output is inverted due to the overflow. The timer
output initial value can be set by the timer output initial value bit (Tn0CR1/Tn1CR1:SO).
156
Figure 11.12-1 Settings for Input Capture Function
bit7 bit6 bit5
IFE C2 C1
❍ ❍ ❍
STA HO IE
❍ ❍
1
TO1 TO0 TIS
❍
× ×
Holds pulse width measurement value
❍: Bit to be used
×: Unused bit
1: Set to "1"
FUJITSU SEMICONDUCTOR LIMITED
MB95630H Series
bit4 bit3 bit2
C0 F3 F2
❍ ❍ ❍
IR BF IF
❍ ❍
×
MOD FE11 FE10
❍ ❍ ❍
bit1 bit0
F1 F0
❍ ❍
SO OE
× ×
FE01 FE00
❍ ❍
MN702-00009-2v0-E