17 16-BIT PWM TIMERS (T16B)
S1C31D50/D51 TECHNICAL MANUAL
Seiko Epson Corporation
17-3
(Rev. 2.00)
17.3 Clock Settings
17.3.1 T16B Operating Clock
When using T16B Ch.
n
, the T16B Ch.
n
operating clock CLK_T16B
n
must be supplied to T16B Ch.
n
from the
clock generator. The CLK_T16B
n
supply should be controlled as in the procedure shown below.
1. Enable the clock source in the clock generator if it is stopped (refer to “Clock Generator” in the “Power Supply,
Reset, and Clocks” chapter).
When an external clock is used, select the EXCL
nm
pin function (refer to the “I/O Ports” chapter).
2. Set the following T16B_
n
CLK register bits:
- T16B_
n
CLK.CLKSRC[2:0] bits (Clock source selection)
- T16B_
n
CLK.CLKDIV[3:0] bits (Clock division ratio selection = Clock frequency setting)
17.3.2 Clock Supply in SLEEP Mode
When using T16B during SLEEP mode, the T16B operating clock CLK_T16B
n
must be configured so that it will
keep supplying by writing 0 to the CLGOSC.
xxxx
SLPC bit for the CLK_T16B
n
clock source.
If the CLGOSC.
xxxx
SLPC bit for the CLK_T16B
n
clock source is 1, the CLK_T16B
n
clock source is deactivated
during SLEEP mode and T16B stops with the register settings and counter value maintained at those before enter-
ing SLEEP mode. After the CPU returns to normal mode, CLK_T16B
n
is supplied and the T16B operation re-
sumes.
17.3.3 Clock Supply During Debugging
The CLK_T16B
n
supply during debugging should be controlled using the T16B_
n
CLK.DBRUN bit.
The CLK_T16B
n
supply to T16B Ch.
n
is suspended when the CPU enters debug state if the T16B_
n
CLK.DBRUN
bit = 0. After the CPU returns to normal operation, the CLK_T16B
n
supply resumes. Although T16B Ch.
n
stops
operating when the CLK_T16B
n
supply is suspended, the counter and registers retain the status before debug state
was entered. If the T16B_
n
CLK.DBRUN bit = 1, the CLK_T16B
n
supply is not suspended and T16B Ch.
n
will
keep operating in debug state.
17.3.4 Event Counter Clock
When EXCL
nm
is selected as the clock source using the T16B_
n
CLK.CLKSRC[2:0] bits, the channel functions as
a timer or event counter that counts the EXCL
nm
pin input clocks.
The counter counts rising edges of the input signal. This can be changed so that the counter will count falling edges
of the original signal by selecting EXCL
nm
inverted input as the clock source.
EXCLnm input
Counter
x
x + 1
x + 2
x + 3
EXCLnm inverted input
Counter
x
x + 1
x + 2
x + 3
Figure 17.3.4.1 Count Timing (During Count Up Operation)
Note: When running the counter using the event counter clock, two dummy clocks must be input be-
fore the first counting up/down can be performed.