ht82a836r Holtek Semiconductor Inc., ht82a836r Datasheet - Page 24

• Manufacturer Part Number: ht82a836r
• Description: Usb Audio Mcu
• Manufacturer: Holtek Semiconductor Inc.

Programmable Frequency Divider - PFD
The Programmable Frequency Divider function, PFD,
allows the generation of a user defined frequency. The
clock source for the PFD is the system clock divided by
4, which after being divided by 16 is then passed
through a programmable prescaler and the PFDD regis-
ter allows a range of user defined frequencies to be gen-
erated.
Overall operation of the PFD is controlled using two reg-
isters, the PFDC register and the PFDD register. As the
PFD output pin is pin-shared with I/O pin PC0, the
PFD_IO bit in the PFDC register is used to select
whether the pin is to be used an a normal I/O function or
The generated frequency of the PFD function is given by the following formula:
Power Amplifier
The SELW bit in the PFDC register is used to control the power amplifier input source. The software should set SELW =
Rev. 1.00
1 when the power amplifier signal come from MUSIC_IN, otherwise the speaker output USB Audio data.
PFD Block Diagram
PFDC Register
24
to be used as a PFD output. The PFDEN bit is used to
control the overall on/off function of the PFD, while bits
PRES0 and PRES1 are used to select the frequency di-
vision ratio of the prescaler. The PFDD register provided
further division of the clock source, however this register
can only be written to when the PFD function is enabled.
If the PFD function is disabled, then all write operations
to the PFDD register will be inhibited. When the PFD is
disabled note that the PFDD register will be automati-
cally cleared. The PFDD contents, the PFD must be en-
abled. When the generator is disabled, the PFDD is
cleared by hardware.
HT82A836R
March 20, 2008