Rohm LAPIS SEMICONDUCTOR ML620Q503, User Manual

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ML620Q503/Q504 User's Manual
Chapter 9 Function Timer(FTM)
FEUL620Q504 9–40
9.3.6 CAPTURE Mode Operation
The CAPTURE mode stores the count value at the time when an event trigger source is generated, to the
FTnEA/FTnEB register. The event trigger source to be captured is common to that used at counter start/stop.
Stored data in FTnEA Counter value at the time when an event trigger rising edge is generated
Stored data in FTnEB Counter value at the time when an event trigger falling edge is generated
9.3.6.1 Measurement Example in the CAPTURE Mode
The following example shows the measurement of the period and duty of PWM input from EXI0 using
CAPTURE mode and counter start/stop by trigger events.
Figure 9-5 Measurement example in the CAPTURE mode
Set the FTnMOD register to the capture mode (FTnMD=01b).
Use the FTnINTE register (FTnIETS=1) to enable the trigger counter stop interrupt.
Use the FTnTRG0 register to set the trigger event source to EXI0 (FTnSTSS=0, FTnSTS=00H), enable counter
start (FTnST0=1), and enable counter stop (FTnST1=1).
Use the FTnTRG1 register to set counter start and stop to rising edge (FTnTRM=00b).
Use the FTnCON0 register to enable the trigger operation (FTnTGEN=1).
The counter starts at rising of EXI0. (

)
Then the counter value is stored to the FTnEB register at falling of EXI0. (

)
When the rising of EXI0 is detected again, the counter stops, and an interrupt occurs. (

)
And the counter value is stored to the FTnEA register at rising of EXI0.
At this time, the values of FTnEA and FTnEB correspond to the period and the duty of EXI0 respectively.
EXI0
Counter
FTnEA

Starts counting

Capture

Stop counting
Capture data.
0
Undefined
Value at stop is kept
Capture data. Undefined FTnEB