7721 datasheet(485/577 Pages) RENESAS

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APPENDIX

Appendix 3. Control registers

7721 Group User’s Manual

17–22

Pulse width modulation (PWM) mode

Timer A2 register (Addresses 4B16, 4A16)

Timer A3 register (Addresses 4D16, 4C16)

Timer A4 register (Addresses 4F16, 4E16)

Functions

Bit

At reset

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

(b15)

(b8)

fi: Frequency of count source (f2, f16, f64, or f512)

(b15)

(b8)

Timer A2 register (Addresses 4B16, 4A16)

Timer A3 register (Addresses 4D16, 4C16)

Timer A4 register (Addresses 4F16, 4E16)

Functions

Bit

At reset

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)

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: Frequency of count source (f2, f16, f64, or f512)

Timer Aj mode register (j = 2 to 4) (Addresses 5816 to 5A16)

0 0 : f2

0 1 : f16

1 0 : f64

1 1 : f512

b7 b6

Count source select bits

At reset

Trigger select bits

Fix this bit to “1” in PWM mode.

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

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

Bit

Bit name

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