hsp43168 Intersil Corporation, hsp43168 Datasheet - Page 14

• Manufacturer Part Number: hsp43168
• Description: Dual Fir Filter
• Manufacturer: Intersil Corporation

For this application, each filter cell is configured as an odd
length filter by writing 110H to the Control Register at
Address 000H. Even though an even tap filter is being
implemented, the filter cells must be configured as odd
length to ensure proper data flow. In addition, the filters
must be set to even symmetry. Also, the 4th bit at Control
Address 001H must be set to disable data reversal, and
TXFR must be tied low. Since an 8-tap asymmetric filter is
being implemented, two sets of coefficients must be stored.
These eight coefficients could be loaded into the first two
coefficient sets for FIR A by writing C0, C1, C2, C3, C7, C6,
C5, and C4 to address 100H, 101H, 102H, 103H, 108H,
109H, 10aH, and 10bH respectively.
The sum of products required for this 8-tap filter require
dynamic control over FWRD, RVRS, ACCEN, and
CSEL0-4. The relative timing of these signals is shown in
Figure 14.
FIGURE 13A. DATA SHIFTING DISABLED, BACKWARD
FIGURE 13C. DATA SHIFTING DISABLED, BACKWARD
C0
C0
SHIFTING DECIMATION REGISTERS FEEDING
MULTIPLIERS
SHIFTING DECIMATION REGISTERS FEEDING
MULTIPLIERS
C1
0
1
7
C1
6
(X1)C0+(X2)C1+(X3)C2+(X4)C3
(X0)C0+(X1)C1+(X2)C2+(X3)C3
ACCUMULATOR
ACCUMULATOR
14
C2
C2
1
2
6
5
FIGURE 13. DATA FLOW DIAGRAMS FOR 8-TAP ASYMMETRIC FILTER
2
C3
3
5
C3
4
3
4
HSP43168
FIGURE 13B. SHIFTING OF DATA SAMPLE 7 INTO FIR CELL
FIGURE 13D. SHIFTING OF DATA SAMPLE 8 INTO FIR CELL
C7
C7
7
8
ENABLED, FORWARD SHIFTING REGISTERS
FEEDING MULTIPLIERS
ENABLED, FORWARD SHIFTING REGISTERS
FEEDING MULTIPLIERS
C6
+(X7)C7+(X6)C6+(X5)C5+(X4)C4
+(X8)C7+(X7)C6+(X6)C5+(X5)C4
C6
(X0)C0+(X1)C1+(X2)C2+(X3)C3
7
0
6
1
(X1)C0+(X2)C1+(X3)C2+(X4)C3
ACCUMULATOR
ACCUMULATOR
C5
C5
6
1
5
2
C4
C4
2
4
3
5
3
4