310
CHAPTER 14 16-BIT RELOAD TIMER
14.4.4 Event Count Mode
The counter counts input edges from the TIN pin to count down the 16-bit counter and
generate an interrupt request to the CPU when a counter underflow occurs. The TOT
pin can output either a toggle waveform or a square wave.
■
Operation in event count mode
When count operation is allowed (TMCSR: CNTE=1) to start the counter (TMCSR: TRG=1), the
value of the 16-bit reload registers (TMRLR) is loaded into the counter for a countdown
whenever a valid edge (leading, trailing, or both edges can be selected) of pulses (external
count clock) input to the TIN pin is detected.
When both the count enable bit and software trigger bit are set to "1" at the same time, counting
will start with counter allowance.
❍
Operation in reload mode
If the counter value causes an underflow ("0000
H
"
→
"FFFF
H
"), the value of the 16-bit reload
registers (TMRLR) is loaded into the counter to continue counting. In this case, an interrupt
request is issued when the timer interrupt request flag (UF) and enable bit for interrupt requests
(TMCSR: INTE) are both set to "1".
The TOT pin outputs a toggle waveform, which is reversed at every occurrence of underflow.
Figure 14.4-10 shows the counting operation in reload mode.
Figure 14.4-10 Count operation in reload mode (event count mode)
Note:
Both the "H" width and "L" width of clock input to the TIN pin shall be 4T (T: machine cycle) or
more.
0000
H
0000
H
0000
H
-1
-1
-1
-1
T*
TIN pin
Counter
Reload
data
Data load signal
Reload
data
Reload
data
Reload
data
UF bit
CNTE bit
TRG bit
TOT pin
T: Machine cycle
* : It takes 1T from trigger input to loading reload data.
Summary of Contents for MB90480 Series
Page 2: ......
Page 4: ......
Page 10: ...vi ...
Page 128: ...106 CHAPTER 4 RESET ...
Page 174: ...152 CHAPTER 6 LOW POWER CONSUMPTION MODE ...
Page 198: ...176 CHAPTER 7 MODE SETTING ...
Page 220: ...198 CHAPTER 9 TIMEBASE TIMER ...
Page 238: ...216 CHAPTER 11 WATCH TIMER ...
Page 280: ...258 CHAPTER 12 16 BIT INPUT OUTPUT TIMER ...
Page 406: ...384 CHAPTER 17 8 10 BIT A D CONVERTER ...
Page 478: ...456 CHAPTER 20 CHIP SELECTION FACILITY ...
Page 494: ...472 CHAPTER 21 ADDRESS MATCH DETECTION FUNCTION ...
Page 498: ...476 CHAPTER 22 ROM MIRROR FUNCTION SELECTION MODULE ...
Page 526: ...504 CHAPTER 23 2M 3M BIT FLASH MEMORY ...
Page 536: ...514 CHAPTER 24 EXAMPLES OF MB90F481B MB90F482B MB90F488B MB90F489B SERIAL PROGRAMMING ...
Page 570: ...548 CHAPTER 25 PWC TIMER ONLY MB90485 SERIES ...
Page 688: ......