Chapter 9
16-bit Timer
IX - 46 16-bit Timer Capture Function
9.8.2 Setup Example
Capture Function Setup Example
Here is an example that, using Timer 7, the value of the binary counter is loaded to the capture register at the
interrupt generation edge of IRQ0 signal to measure the pulse width. The rising edge is selected for the interrupt
generation edge and capture trigger generation edge.
The following is an example of setup procedures.
Figure:9.8.5 Pulse Width Measurement of External Interrupt 0 Input Signal
TM7BC counts up from "0x0000". Synchronizing with the External Interrupt 0 input signal, the value of TM7BC
is loaded to TM7IC.
At that time, the pulse width from a rising edge of the external interrupt input signal to the next rising edge can be
measured by reading the value of TM7IC through the interrupt process and calculating the difference between that
value and the last capture value (the last value of TM7IC).
Step Setting Register Description
1 Disable the timer counter TM7MD.TM7EN = 0 Disable the timer count operation.
2 Disable the interrupt TM7ICR.TM7IE = 0 Disable the timer interrupt.
3 Set the timer mode register TM7MD2.TM7BCR = 1 Select the TM7BC clear source.
4
TM7MD1.TM7CK1-0 = 00
TM7MD1.TM7PS1-0 = 00
Select HCLK as the count clock source.
5 Set the compare register TM7PR1 = 0xFFFF Setup data in TM7PR1 is loaded to TM7OC1.
6 Set the timer mode register TM7MD2.T7ICT1-0 = 00 Select the capture trigger source.
7
TM7MD1.T7ICEDG1 = 1
TM7MD2.T7ICEDG0 = 1
Select the capture trigger edge.
8
Set the external interrupt IRQISEL0.IRQ0SEL = 0
IRQIEN.IRQI0EN = 1
Enable the external interrupt pin.
9 Set the timer mode register TM7MD3.TM7CKSMP = 0 Select the count clock for capture sampling.
10 Set the external interrupt IRQ0ICR.REDG0 = 1 Set the external interrupt valid edge.
11 Set the interrupt level IRQ0ICR.IRQ0LV1-0 Refer to [3.1.3 Maskable Interrupt Control Register Setup].
12 Enable the interrupt IRQ0ICR.IRQ0IE = 1
13 Set the timer mode register TM7MD2.T7ICEN = 1 Enable the capture trigger function
14 Enable the timer counter TM7MD1.TM7EN = 1 Enable the timer count operation.
External Interrupt 0
IRQ0 input
Pulse width to be measured
interrupt
processing
interrupt
processing
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