
APPENDIX
Appendix 3. Control registers
7721 Group User’s Manual
17–22
Pulse width modulation (PWM) mode
b7
b0
b7
b0
Timer A2 register (Addresses 4B16, 4A16)
Timer A3 register (Addresses 4D16, 4C16)
Timer A4 register (Addresses 4F16, 4E16)
Functions
Bit
At reset
RW
15 to 0 These bits can be set to “000016” to “FFFE16.”
Assuming that the set value = n, the “H” level
width of the PWM pulse output from the
TAjOUT pin is expressed as follows:
(PWM pulse period =
)
Undefined
<When operating as a 16-bit pulse width modulator>
(b15)
(b8)
WO
n
fi
fi: Frequency of count source (f2, f16, f64, or f512)
<When operating as an 8-bit pulse width modulator>
(b15)
b7
b0
b7
b0
(b8)
Timer A2 register (Addresses 4B16, 4A16)
Timer A3 register (Addresses 4D16, 4C16)
Timer A4 register (Addresses 4F16, 4E16)
Functions
Bit
At reset
RW
7 to 0
15 to 8
Undefined
These bits can be set to “0016” to “FF16.”
Assuming that the set value = m, PWM
pulse’s period output from the TAjOUT pin is
expressed as follows:
(m + 1)(28 – 1)
fi
WO
These bits can be set to “0016” to “FE16.”
Assuming that the set value = n, the “H” level
width of the PWM pulse output from the
TAjOUT pin is expressed as follows:
n(m + 1)
fi
WO
fi: Frequency of count source (f2, f16, f64, or f512)
b7
b6
b5
b4
b3
b2
b1
b0
Timer Aj mode register (j = 2 to 4) (Addresses 5816 to 5A16)
7
0 0 : f2
0 1 : f16
1 0 : f64
1 1 : f512
b7 b6
Count source select bits
11
1
At reset
0
RW
Trigger select bits
Fix this bit to “1” in PWM mode.
1
Operating mode select bits
Functions
1 1 : PWM mode
b1 b0
b4 b3
16/8-bit PWM mode select bit
0 0 :
Writing “1” to count start register
0 1 : (TAj IN pin functions as a pro-
grammable I/O port.)
1 0 : Falling edge of TAjIN pin’s input signal
1 1 : Rising edge of TAjIN pin’s input signal
0 : 16-bit pulse width modulator
1 : 8-bit pulse width modulator
4
0
2
3
5
6
0
RW
Note: Use the LDM or STA instruction for writing to this register.
Read from or write to this register in a unit of 16 bits.
Note: Use the LDM or STA instruction for writing to this register.
Read from or write to this register in a unit of 16 bits.
n16 – 1
fi
Bit
Bit name