Specifications

DATA SHEET QF4A512
Rev D4, Dec 07 56 www.quickfiltertech.com
(C1TH1_0 - C1TH1_7): Represents the LSB in half of TAP1 Coefficient Data for Channel 1.
Description: This is the LSB of the 16 bit Coefficient Data for the first unique TAP value. The H filter has a fixed set of 89 taps.
Because the Taps are mirrored, only 45 unique 16 bit coefficients are stored. Since this is an odd number of taps, you have to
add 1 to 89= 90/2 = 45. The starting address for the H filter is after the G filter coefficients end. This would then be (8 Unique
taps x 2 bytes each) = 16 bytes. So, the H filter for Channel 1 would start at 100h + 16 = 110h.
The next unique Tap value would start at 112h, Tap3 would start at 114h and so on until all 45 values were entered.
Channel 2: FIR_1_0_COEF_RAM Address 190h
Channel 3: FIR_2_0_COEF_RAM Address 210h
Channel 4: FIR_3_0_COEF_RAM Address 290h
111h FIR_0_0_COEF_RAM (Coefficients for H Filter per Channel, MSB)
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Channel1 11Dh C1TH1_15 C1TH1_14 C1TH1_13 C1TH1_12 C1TH1_11 C1TH1_10 C1TH1_9 C1TH1_8
Channel2 19Dh C2TH1_15 C2TH1_14 C2TH1_13 C2TH1_12 C2TH1_11 C2TH1_10 C2TH1_9 C2TH1_8
Channel3 21Dh C3TH1_15 C3TH1_14 C3TH1_13 C3TH1_12 C3TH1_11 C3TH1_10 C3TH1_9 C3TH1_8
Channel4 29Dh C4TH1_15 C4TH1_14 C4TH1_13 C4TH1_12 C4TH1_11 C4TH1_10 C4TH1_9 C4TH1_8
*Note, Failure to write both addresses 110h and 111h will result in nothing being written to either of the addresses.
(C1TH1_8 - C1TH1_15): Represents the MSB in half of TAP1 Coefficient Data for Channel 1.
Description: This is the MSB of the 16 bit Coefficient Data for the first unique TAP value. The H filter has a fixed set of 89 taps.
Because the Taps are mirrored, only 45 unique 16 bit coefficients are stored. Since this is an odd number of taps, you have to
add 1 to 89= 90/2 = 45 coefficients. The starting address for the H filter would then be (8 Unique taps x 2 bytes each) = 16 bytes.
So, the H filter for Channel 1 would start at 101h + 16 = 111h.
The next unique Tap value would start at 113h, Tap3 would start at 115h and so on until all 45 values were entered.
Channel 2: FIR_1_0_COEF_RAM Address 191h
Channel 3: FIR_2_0_COEF_RAM Address 211h
Channel 4: FIR_3_0_COEF_RAM Address 291h
300h FIR_0_1_COEF_RAM (Coefficients for FIR Filter per Channel, LSB, Byte 1)
Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
Channel1 300h C1T1_7 C1T1_6 C1T1_5 C1T1_4 C1T1_3 C1T1_2 C1T1_1 C1T1_0
Channel2 600h C2T1_7 C2T1_6 C2T1_5 C2T1_4 C2T1_3 C2T1_2 C2T1_1 C2T1_0
Channel3 900h C3T1_7 C3T1_6 C3T1_5 C3T1_4 C3T1_3 C3T1_2 C3T1_1 C3T1_0
Channel4 C00h C4T1_7 C4T1_6 C4T1_5 C4T1_4 C4T1_3 C4T1_2 C4T1_1 C4T1_0
*Note, Failure to write addresses 300h, 301, and 302h will result in nothing being written to any of the addresses.
(C1T1_0 - C1T1_7): Represents the LSB in three bytes storing 20 bits of data for a unique tap coefficient.
Description: This is the LSB of the 20 bit Coefficient Data for the first unique TAP value for the FIR filter. The FIR filter can have
up to 512 taps depending on the filter design. Because the Taps are mirrored, only half of the actual taps are stored in coefficient
RAM. Since most likely it will be an odd number of taps design, the extra "non-mirrored" tap is added to the number of unique
tap coefficients. Example, if a low pass filter design required 137 taps, the number of unique taps would be 137+1 = 138 /2 = 69
unique tap coefficients. Each coefficient is 20 bits, requiring 3 bytes of space for each coefficient. The data is shifted to the
least significant bit.
The next unique Tap value would start at 303h, Unique Tap3 value would start at 306h and so on until all 69 values were entered.
Channel 2: FIR_1_1_COEF_RAM Address 600h
Channel 3: FIR_2_1_COEF_RAM Address 900h
Channel 4: FIR_3_1_COEF_RAM Address C00h