TIMER A
7.4 Event counter mode
Table 7.4.2 Specifications of event counter mode (when using two-phase pulse signal processing
function in timers A2, A4, and A9)
Item
Specifications
External signal (two-phase pulse) input to the following pins:
• TA2IN, TA2OUT
Count source
• TA4IN, TA4OUT
• TA9IN, TA9OUT
Count operation
Division ratio
ꢀ Countup or countdown can be switched by external signal (two-
phase pulse).
ꢀ When a counter overflow or underflow occurs, reload register’s con-
tents are reloaded, and counting continues.
ꢀ For countdown
1
(n + 1)
ꢀ For countup
n: Timer A2/A4/A9 register’s set value
1
(FFFF16 – n + 1)
Count start condition
Count stop condition
Interrupt request occurrence timing
Function of the following pins:
• TA2IN, TA2OUT
When the count start bit is set to “1.”
When the count start bit is cleared to “0.”
When a counter overflow or underflow occurs.
Two-phase pulse input
• TA4IN, TA4OUT
• TA9IN, TA9OUT
Read from timer A2/A4/A9 register Counter value can be read out by reading timer A2/A4/A9 register.
Write to timer A2/A4/A9 register
ꢀꢀWhile counting is stopped
When a value is written to timer A2/A4/A9 register, it is written to
both of the reload register and counter.
ꢀ While counting is in progress
When a value is written to timer A2/A4/A9 register, it is written only to the
reload register. (Transferred to the counter at the next reload timing.)
7906 Group User’s Manual Rev.2.0
7-19
RENESAS [ RENESAS TECHNOLOGY CORP ]
