TIMER A
7.4 Event counter mode
7.4.1 Setting for event counter mode
Figures 7.4.2 and 7.4.3 show an initial setting example for registers related to the event counter mode.
Note that when using interrupts, set up to enable the interrupts. For details, refer to “CHAPTER 6.
INTERRUPTS.”
Selecting event counter mode and each function
b7
b0
Timer Aj mode register (j = 0 to 2, 4, 9)
0
1
ꢀ ꢀ 0
(Addresses 5616 to 5816, 5A16, DA16
)
Selection of event counter mode
Pulse output function select bit
0: No pulse output
1: Pulse output
Count polarity select bit
0: Counts at falling edge of external signal.
1: Counts at rising edge of external signal.
Up-down switching factor select bit
0: Contents of up-down register
1: Input signal to TAjOUT pin
X: It may be either “0” or “1.”
Setting up–down register
b7
b0
Up–down register 0 (Address 4416
)
0
0
Timer A0 up–down bit
Set to the corresponding up–down bit when the
contents of the up-down register are selected as
the up-down switching factor.
Timer A1 up–down bit
Timer A2 up–down bit
Timer A4 up–down bit
0: Countdown
1: Countup
Timer A2 two–phase pulse
signal processing select bit
Set the corresponding bit to “1” when the
two–phase pulse signal processing function
is selected for timers A2 and A4.
0: Two–phase pulse signal processing
function disabled
Timer A4 two–phase pulse
signal processing select bit
b7
b0
1: Two–phase pulse signal processing
function enabled
Up–down register 1 (Address C416
)
0
0
0
0
0
0
Set to the corresponding up–down bit when the contents
of the up-down register are selected as the up-down
switching factor.
Timer A9 up–down bit
0: Countdown
1: Countup
Timer A9 two–phase pulse
signal processing select bit
Set the corresponding bit to “1” when the
two–phase pulse signal processing function
is selected for timer A9.
0: Two–phase pulse signal processing
function disabled
1: Two–phase pulse signal processing
function enabled
Setting divide ratio
(b15)
b7
Timer A0 register (Addresses 4716, 4616
Timer A1 register (Addresses 4916, 4816
)
)
(b8)
b0 b7
b0
Timer A2 register (Addresses 4B16, 4A16
Timer A4 register (Addresses 4F16, 4E16
Timer A9 register (Addresses CF16, CE16
)
)
)
Can be set to
“000016” to “FFFF16” (n).
ꢀꢀThe counter divides the count source frequency by (n + 1)
when counting down, or by (FFFF16 – n + 1) when counting up.
Continued to Figure 7.4.3
on the next page
Fig. 7.4.2 Initial setting example for registers related to event counter mode (1)
7906 Group User’s Manual Rev.2.0
7-21
RENESAS [ RENESAS TECHNOLOGY CORP ]
