MITSUBISHI MICROCOMPUTERS
M37754M8C-XXXGP, M37754M8C-XXXHP
M37754S4CGP, M37754S4CHP
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
TIMER
(1) Timer mode [00]
There are eight 16-bit timers. They are divided by type into timer A(5)
Figure 18 shows the bit configuration of the timer Ai mode register
during timer mode. Bits 0 and 1 of the timer Ai mode register must be
“0” in timer mode. Bits 3, 4, and 5 are used to select the gate func-
tion. Bits 4 and 5 must be “0” when not selecting the gate function.
Bit 3 is ignored if bit 4 is “0”.
and timer B(3).
The timer I/O pins are multiplexed with I/O pins for port P5 and P6.
To use these pins as timer input pins, the data direction register bit
corresponding to the pin must be cleared to “0” to specify input mode.
Bits 6 and 7 are used to select the timer counter source.
The counting of the selected clock starts when the count start bit is
“1” and stops when it is “0”.
TIMER A
Figure 17 shows a block diagram of timer A.
Figure 19 shows the bit configuration of the count start bit. The
counter is decremented, an interrupt is caused and the interrupt re-
quest bit in the timer Ai interrupt control register is set when the con-
tents becomes 000016. At the same time, the contents of the reload
register is transferred to the counter and count is continued.
When data is written to timer Ai register with timer Ai halted, the same
data is also written to the reload register and the counter. When data
is written to timer Ai which is busy, the data is written to the reload
register, but not to the counter. The new data is reloaded from the re-
load register to the counter at the next reload time and counting con-
tinues. The contents of the counter can be read at any time.
When the value set in the timer Ai register is n, the timer frequency
dividing ratio is 1/(n+1).
Timer A has four modes: timer mode, event counter mode, one-shot
pulse mode, and pulse width modulation mode. The mode is se-
lected with bits 0 and 1 of the timerAi mode register (i = 0 to 4). Each
of these modes is described below.
Data bus (odd)
Data bus (even)
(Lower 8 bits)
(Higher 8 bits)
Clock source selection
• Timer
Pf
2
• One-shot
Reload register(16)
• Pulse width modulation
Pf16
Pf64
Timer(gate function)
Event counter
Pf512
Counter(16)
A
ddresses
Up/Down
Polarity
selection
Count start bit
(4016
Down count
Always decremented
except in event count mode
Timer A0 4716 4616
Timer A1 4916 4816
Timer A2 4B16 4A16
Timer A3 4D16 4C16
Timer A4 4F16 4E16
TAiIN
(i = 0–4)
)
External trigger
Up-down bit
(4416
)
Pulse output
Toggle flip-flop
TAiOUT
(i = 0–4)
Note: Perform write and read to/from timer Ai register in the condition of 16-bit data length : data length flag (m) = “0”.
Fig. 17 Block diagram of timer A
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RENESAS [ RENESAS TECHNOLOGY CORP ]
