ISD94100 Series Technical Reference Manual
Sep 9, 2019
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b1_1 = 2 *b0
b2_1 = b0
a1_1 = 2*(TK^2-1)*norm
a2_1 = (1-TK/Q T+K^2) * norm
b0_2=T K^2 *norm
b1_2 = 2 *b0
b2_2 = b0
a1_2 = 2*(TK^2-1)*norm
a2_2 = (1-TK/Q +TK^2) * norm
b0_3 = norm
b1_3 = -2 *b0
b2_3 = b0
a1_3 = 2*(TK^2-1)*norm
a2_3 = (1-TK/Q +TK^2) * norm
b0_4 = norm
b1_4 = -2 *b0
b2_4 = b0
a1_4 = 2*(TK^2-1)*norm
a2_4 = (1-TK/Q +K^2) * norm
6.21.5.4 Splitter Configuring
The splitter is cross-over with LR4 to generate left, right and sub-woofer channel shared biquad
filter 4 bands. Note that when configure coefficients, the biquad filter (BIQON (DPWM_CTL[21]) =
0) and splitter (SPLTON (DPWM_CTL[22]) = 0) must be turned off. Splitter uses 4 bands of
coefficient.
To configure the splitter:
Reset audio DPWM modulator by setting register
DPWMRST (SYS_IPRST2[6]).
Enable coefficient RAM programming mode by setting register PRGCOEFF
(DPWM_COEFFCTL[0]) to “1”.
Set 4 bands of splitter coefficient in register COEFFDAT (DPWM_COEFFn, n = 0~19). The
coefficient uses band1 to band4.
Disable coefficient RAM programming mode by setting register PRGCOEFF
(DPWM_COEFFCTL[0]) to “0”.
Set biquad filter band number to “4” in register BIQBANDNUM (DPWM_CTL[27:24]).
Enable splitter by setting register SPLTON (DPWM_CTL[22]) to “1”.
The following is splitter frequency response and channel distribution. The splitter does frequency