306
CHAPTER 14 16-BIT RELOAD TIMER
14.4.2 Operations of Internal Clock Mode (Reload Mode)
The counter operates in sync with the internal count clock to count down the 16-bit
counter and generate an interrupt request to the CPU in case of counter underflow.
The counter also outputs a toggle waveform from the timer output pin.
■
Operations of internal clock mode (reload mode)
If, with count operation enabled (TMCSR: CNTE = 1), the software trigger bit (TMCSR: TRG) or
external trigger is set to start the timer, the value in the reload register (TMRLR) is loaded into
the counter, and counter operation starts.
If both the counter enabled bit and the software trigger bit is set to "1" at the same time,
counting will start as soon as counter operation is enabled. If the counter value causes an
underflow("0000
H
"
→
"FFFF
H
"), the value in the 16-bit reload register (TMRLR) is loaded into the
counter to continue with the counting operation. At this time, the underflow interrupt request flag
bit (UF) is set to "1", and if the interrupt request enable bit (INTE) is set to "1", an interrupt
request is generated. It outputs a toggle waveform that is inverted at every underflow via the
TOT pin.
❍
Software trigger operation
With the TRG bit of the timer control status register (TMCSR) set to "1", the counter is started.
Figure 14.4-4 shows the software trigger operation for a reload.
Figure 14.4-4 Count operation in reload mode (software trigger operation)
Count clock
Counter
Data load signal
UF bit
CNTE bit
TRG bit
TOT pin
T
*
T : Machine cycle * : The time from trigger input to loading the reload data is 1T.
Reload
data
Reload
data
Reload
data
Reload
data
-1
-1
0000
H
0000
H
0000
H
-1
-1
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: ......