84
Mitsubishi microcomputers
M16C / 62T Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
Timer A
Timer A
Figure 1.17.3 shows the block diagram of timer A. Figures 1.17.4 to 1.17.6 show the timer A-related
registers.
Except in event counter mode, timers A0 through A4 all have the same function. Use the timer Ai mode
register (i = 0 to 4) bits 0 and 1 to choose the desired mode. But M30623(80-pin package), timer A1 and A2
have no I/O pin, so it operate as only internal timer.
Timer A has the four operation modes listed as follows:
Timer mode: The timer counts an internal count source.
Event counter mode: The timer counts pulses from an external source or a timer over flow.
One-shot timer mode: The timer stops counting when the count reaches “000016”.
Pulse width modulation (PWM) mode: The timer outputs pulses of a given width.
Figure 1.17.4. Timer A-related registers (1)
Count start flag
(Address 038016)
Up count/down count
TAi
Addresses
TAj
TAk
Timer A0
038716
038616
Timer A4
Timer A1
038916
038816
Timer A0
Timer A2
038B16
038A16
Timer A1
Timer A3
038D16
038C16
Timer A2
Timer A4
038F16
038E16
Timer A3
Timer A0
Always down count except
in event counter mode
Reload register (16)
Counter (16)
Low-order
8 bits
High-order
8 bits
Clock source
selection
Timer
(gate function)
Timer
One shot
PWM
f1
f8
f32
External
trigger
TAiIN
(i = 0 to 4)
TB2 overflow
Event counter
fC32
Clock selection
TAj overflow
(j = i – 1. Note, however, that j = 4 when i = 0)
Pulse output
Toggle flip-flop
TAiOUT
(i = 0 to 4)
Data bus low-order bits
Data bus high-order bits
Up/down flag
Down count
(Address 038416)
TAk overflow
(k = i + 1. Note, however, that k = 0 when i = 4)
Polarity
selection
Note 1: In M30623(80-pin package), do not select the function using TA1IN, TA1OUT, or TA2IN, and TA2OUT because
these are not connected to the external pin.
Note 2: The TA0IN pin (P71) is shared with the TB5IN pin, RxD2, and SCL pin.
Timer Ai mode register
Symbol
Address
When reset
TAiMR(i=0 to 4)
039616 to 039A16
0016
Bit name
Function
Bit symbol
W
R
b7
b6
b5
b4
b3
b2
b1
b0
0 0 : Timer mode
0 1 : Event counter mode
1 0 : One-shot timer mode
1 1 : Pulse width modulation
(PWM) mode
b1 b0
TCK1
MR3
MR2
MR1
TMOD1
MR0
TMOD0
TCK0
Function varies with each operation mode
Count source select bit
(Function varies with each operation mode)
Operation mode select bit
Figure 1.17.3. Block diagram of timer A