m37905 Renesas Electronics Corporation., m37905 Datasheet - Page 121

• Manufacturer Part Number: m37905
• Description: Mitsubishi 16-bit Single-chip Microcomputer 7700 Family / 7900 Series
• Manufacturer: Renesas Electronics Corporation.

of the timer Ai register and timer Ai mode register in the event counter mode.
Count source
Count operation
Division ratio
Count start condition
Count stop condition
Interrupt request occurrence timing
TAi
TAi
Read from timer Ai register
Write to timer Ai register
TIMER A
7.4 Event counter mode
7.4 Event counter mode
In this mode, the timer counts an external signal.
Tables 7.4.1 and 7.4.2 list the specifications of the event counter mode. Figure 7.4.1 shows the structures
Table 7.4.1 Specifications of event counter mode (when not using two-phase pulse signal processing
7-18
IN
OUT
pin’s function
pin’s function
function)
Item
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.
Count source input
Programmable I/O port pin, pulse output pin, or countup/countdown
switch signal input pin
Counter value can be read out.
7905 Group User’s Manual Rev.1.0
External signal input to the TAi
The count source’s valid edge can be selected from the falling edge
and the rising edge by software.
Countup or countdown can be switched by external signal or software.
When a counter overflow or underflow occurs, reload register’s con-
tents are reloaded, and counting continues.
While counting is stopped
When a value is written to timer Ai register, it is written to both of
the reload register and counter.
While counting is in progress
When a value is written to timer Ai register, it is written only to the
reload register. (Transferred to the counter at the next reload timing.)
For countdown
For countup
(FFFF
(n + 1)
16
1
1
– n + 1)
Specifications
IN
n: Timer Ai register’s set value
pin