Fujitsu FR81S User Manual
CHAPTER 24: 16-BIT FREE-RUN TIMER
4. Registers
FUJITSU SEMICONDUCTOR LIMITED
CHAPTER : 16-BIT FREE-RUN TIMER
FUJITSU SEMICONDUCTOR CONFIDENTIAL
17
[bit31] ECKE: Clock selection bit
ECKE
Function
0
Peripheral clock
1
External clock
⋅
This bit is used for selecting the peripheral clock or external clock as a count clock for the 16-bit free-run
timer.
⋅
When this bit is set to "0":
The peripheral clock is selected. To select the count clock frequency, you will also need to select the clock
frequency selection bits (CLK3 to CLK0) of the TCCS register.
⋅
When this bit is set to "1":
The external clock (FRCK) is selected.
Note:
The count clock will be changed immediately as soon as this bit is set. Therefore, you need to change this
bit while the output compare and input capture are inactive.
[bit30] IRQZF: 0 detection interrupt flag bit
IRQZF
Function
Read
Write
0
No 0 detected
This bit is cleared
1
0 detected
This bit remains unaffected
⋅
When the count value of the 16-bit free-run timer is set to "0000
H
", this bit will be set to "1".
⋅
When this bit is set to "0": This bit is cleared.
⋅
When this bit is set to "1": This bit remains unaffected.
⋅
This bit is cleared when the 0 detection interrupt clear signal is "H".
Notes:
If a read-modify-write (RMW) instruction is executed, "1" is always read.
This bit will not be set by software clear (write "1" to the SCLR: bit20 of the timer state control register
(TCCS)) while the 16-bit free-run timer is active (STOP:bit22 of timer state control register (TCCS) is 0).
In the up/down count mode (MODE: bit21 of the timer state control register (TCCS) is 1), this bit will be set
to "1" when an interrupt configured by the interrupt mask selection bits (MSI2 to MSI0: bit28 to bit26 of the
timer state control register (TCCS) is other than "000
B
") occurs. If no interrupt occurs, this bit will not be set
to "1".
In the up count mode (MODE:bit21=0), this bit will be set every time 0 detection occurs regardless of the
value of MSI2 to MSI0: bit28 to bit26.
If a software clear (write of "0") or a clear due to an interrupt clear signal ("H") and a hardware set occur at the
same time, the hardware set takes precedence.
MB91520 Series
MN705-00010-1v0-E
924