Fujitsu F2MC-8L MB89620 Series Hardware Manual page 204

l Count clock selector
Selects the internal count clock (1 t
detector for the counter function. The 16-bit counter (TCR register) uses the selected signal as
the count-up clock.
Edge detector
l
Operates when the counter function is selected, and detects rising, falling, or both edges of
pulses input from the EC pin.
TCR register
l
This 16-bit counter counts-up from the value set in the register. The counter function sets the
interrupt request flag bit (TCEF = "1") in the TMCR register when the counter value overflows.
TMCR register
l
The TMCR register is used to select the function, enable or disable operation, control interrupts,
and check the timer/counter status.
Lower 8-bit latch
l
Stores the lower 8 bits of the 16-bit counter whenever a read occurs for the upper 8 bits of the
TCR register (TCHR). As the lower 8 bits of the counter (TCLR) are read from the lower 8-bit
latch, the correct 16-bit counter value can be read even if the counter is counting up.
Check: Reading the lower 8 bits followed by the upper 8 bits of the TCR register while the counter is
operating may result in an incorrect value being read if a counter carry occurs.
Therefore, always use word transfer instructions to read the TCR register.
MB89620 series
) for the interval timer function or the output of the edge
inst
CHAPTER 9 16-BIT TIMER/COUNTER
183