HE84760 Datasheet, PDF (24/31 Pages) King blillion Electronics Co.,Ltd. – 8-bit Micro-controller

King Billion Electronics Co., Ltd
駿億電子股份有限公司
The output current of the DAC is programmable by mask option MO_DACISEL:
MO_DACISEL[1:0] DAC Output Current
00
0.375 mA
01
0.75 mA
10
1.5 mA
11
3 mA
HE84760
HE80000 SERIES
16. Pulse-Width Modulation
The pulse-width modulator (PWM) converts 7-bit unsigned speech data written to PWMC data register to
proportional duty cycle of PWM output. PWM module shares the PWMC data register with
Digit-to-Analog Converter. So PWM and DA output can exist at the same time. When PWM circuit is
enabled, it generates signal with duty ratio in proportion to the DA value.
DA = 0x20
DA = 0x80
DA = 0xE0
1 subframe
The PWM bit of VOC register controls register to enable the circuit and output driver. When PWM bit of
VOC is ‘0’, PWME bit and output drivers settings are both cleared. To use PWM for voice output, PWM
bit has to be set to ‘1’ first, then set PWME bit and enable output driver by setting the driver number. If
PWM bit is disabled and enabled again, the setting for driver and PWME bit will be clear.
The Fast Clock is gated through PWME bit of PWMC command register to provide the clock source of
PWM circuit when it is enabled. As PWM needs higher frequency to operate, it cannot generate correct
PWM signal in Slow clock only mode.
When the program enters into Sleep mode or Idle mode, it will automatically turn off all voice outputs by
clearing VOC[2:1] to ”00”. To activate voice output again when returning to Normal Mode, the VOC
register needs to be set again.
The PWM output volume can be adjusted by command register PWMC[6:4]. The bit 6 and 5 control 2
time driver, while bit 4 controls 1 time driver, thus it has 5 levels of driver output. By turning on/off the
internal drivers, the sound level of PWM output can be turned up and down. Please note that this
adjustment apply only to PWM, but not DA output.
August 15, 2003
Page 24 of 31
V1.2
This specification is subject to change without notice. Please contact sales person for the latest version before use.