ht82a836r Holtek Semiconductor Inc., ht82a836r Datasheet - Page 43

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

FIFO Registers
DAC Limit Registers
The DAC_Limit_L and DAC_Limit_H registers are used to define the 16-bit DAC output limits. The values in the
DAC_Limit_L and DAC_Limit_H registers are unsigned values. If the 16-bit data from the Host exceeds that of the
range defined by the two DAC_Limit_L and DAC_Limit_H registers then the output digital code to DAC will be clamped
within these register values.
Example to set the DAC output limit values:
;-----------------------------------------------------------
; Set DAC Limit Value=FF00H
;-----------------------------------------------------------
clr
set
;-----------------------------------------------------------
In order to prevent a popping noise from the speaker output, the power amplifier should output a value of V
means a value of 8000H should be sent to the DAC during the initial power on state. Generating a pulse on the
DAC_WR_TRIG bit will write the values into the DAC. If the DAC_WR_TRIG, bit 3 of the DAC_WR register, is already
high then clearing the DAC_WR_TRIG bit, will write the values into the DAC_Limit_L and DAC_Limit_H registers for
the DAC.
Note:
Rev. 1.00
Registers
FIFO0~
FIFO4
In the DAC write data mode (high nibble of WDTS register is 0101b), the DAC_Limit_L and DAC_Limit_H reg-
isters will be the 16-bit DAC input data register at the falling edge of DAC_WR_TRIG. Otherwise, these two
registers are used to define the 16-bit DAC output limit (repeated below).
[02DH] ; Set DAC Limit low byte=00H
[02EH] ; Set DAC Limit high byte=FFH
R/W
R/W
FIFO0~FIFO4 (28H~2CH) USB Endpoint Accessing Registers Definitions
DAC_Limit_H
DAC_Limit_L
Power-on
xxH
DAC Write and Record Source Register - DAC_WR
EPi accessing register EPSX bits in the UCC register. (i = 0~4). When an end-
point is disabled, the corresponding accessing register should be disabled.
43
DAC output limit low byte
DAC output limit high byte
Function
HT82A836R
March 20, 2008
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