
273
12.3 Multifunctional Timer Registers
Table 12.3-1 Functions of Bits for Timer Control Status Register (Upper) (TCCS)
Bit name
Function
bit15
ECKE:
Count clock source
setting bit
This bit is used to specify whether the machine clock or an external clock is
used as the count clock of the 16-bit free-running timer.
The count clock source is changed immediately after the bit is set.
Therefore, change the clock source while the output compare and input
capture units are stopped.
Note:
To set the machine clock, set the count clock setting bits (CLK2 to
CLK0).
To set an external clock, set the FRCK pin as an input port (DDR1:
bit15="0").
bit14
bit13
-:
Undefined bit
If these bits are read, the values are undefined. Values set to these bits do
not affect operation.
bit12
bit11
bit10
MSI2, MSI1, MSI0:
Interrupt mask count
setting bit
These bits set the number of times a compare clear interrupt is to be
masked. The set value becomes the mask count directly.
Example:
If "010B" is set, interrupt processing is performed at the 3rd request after
masking twice.
If "000B" is set, no interrupt cause is masked.
bit9
ICLR:
Compare clear
interrupt request flag
bit
This bit is a flag that requests an interrupt.
If the counter value and the compare clear register (CPCLR) value of the
16-bit free-running timer match and the counter value is then cleared (bit4:
MODE="1") to "0000H", this bit is set to "1".
When this bit is set to "1" while the compare clear interrupt enable bit (bit8:
ICRE) is "1", an interrupt request is output.
If this bit is "0", an interrupt request is cleared.
If this bit is "1", operation is not affected.
A read-modify-write instruction always reads "1" from this bit.
bit8
ICRE:
Compare clear
interrupt request
enable bit
This bit enables an interrupt request.
When the compare clear interrupt request flag bit (bit9: ICLR) is set to "1"
while this bit is "1", an interrupt request is output.