
Timer A
Mitsubishi microcomputers
M30220 Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
67
Timer A
Figure 1.13.3 shows the block diagram of timer A. Figures 1.13.4 to 1.13.8 show the timer A-related
registers.
Use the timer Ai mode register (i = 0 to 7) bits 0 and 1 to choose the desired mode.
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 1.13.4. Timer A-related registers (1)
Figure 1.13.3. Block diagram of timer A
Count start flag
(Address 034016, 038016)
Up count/down count
TAi
Addresses
TAj
TAk
TBm
Timer A0
038716 038616
Timer A4
Timer A1
Timer B2
Timer A1
038916 038816
Timer A0
Timer A2
Timer B2
Timer A2
038B16 038A16
Timer A1
Timer A3
Timer B2
Timer A3
038D16 038C16
Timer A2
Timer A4
Timer B2
Timer A4
038F16 038E16
Timer A3
Timer A0
Timer B2
Timer A5
034716 034616
Timer A7
Timer A6
Timer B5
Timer A6
034916 034816
Timer A5
Timer A7
Timer B5
Timer A7
034B16 034A16
Timer A6
Timer A5
Timer B5
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 7)
TBm overflow
(m = 2 when i
4, m = 5 when i
5)
Event counter
fC132
Clock selection
TAj overflow
(j = i –1. Note, however, that j = 4 when i = 0,
j = 6 when i = 5, j = 5 when i = 7)
Pulse output
Toggle flip-flop
TAiOUT
(i = 0 to 7)
Data bus low-order bits
Data bus high-order bits
Up/down flag
Down count
(Address 034416, 038416)
TAk overflow
(k = i + 1. Note, however, that k = 0 when i = 4,
k = 7 when i = 5, k = 6 when i = 7)
Polarity
selection
Timer Ai mode register
Symbol
Address
When reset
TAiMR(i=0 to 4)
039616 to 039A16
0016
(i=5 to 7)
035616 to 035816
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