Texas Instruments MSP50C6xx manual Coeffarray address FIRK/CORK only Program memory FIRK/CORK

Models: MSP50C6xx

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Special Filter Instructions

Figure 4–6. Setup and Execution of MSP50P614/MSP50C614 Filter Instructions, N+1 Taps

DP

Rxeven+1 {R1,R3,R5,R7}

Rxeven

{R0,R2,R4,R6}

R5

An = ACn

coeff_array address

 

FIRK/CORK only Program memory (FIRK/CORK)

 

 

 

 

 

 

 

 

 

 

 

 

coeff_array address

 

 

 

 

 

 

 

coeff_array

 

 

 

 

 

 

 

 

sample_buf address

 

Coefficients, h[k]

 

 

 

 

 

 

 

 

 

 

 

 

 

 

FIR/COR only

k = 0..N

 

 

 

 

 

 

 

 

 

 

 

Circular buffer operation only

 

 

 

 

 

 

 

 

 

Data memory

 

 

 

Circular buffer length, –2N

 

 

 

 

(FIR/COR)

 

 

 

Accumulators Pointer

coeff_array

 

 

 

Coefficients, h[k]

 

 

 

 

 

 

Point to accumulator, ACr

 

 

k = 0..N

 

 

 

 

 

 

 

sample_buf

Past N samples,

 

 

x[k]

TAG=1 for 2nd to last sample for

Circular buffer operation

 

Accumulators

 

PH

Multiplier

 

 

 

MR

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

ACr

0–15thbits of y￿

 

+

 

 

 

 

For COR/CORK

 

 

 

 

 

ACr+1

16–31stbits of y

 

+

 

 

 

 

 

 

 

y =

ACr+2

ACr+1

ACr

 

 

 

 

 

 

 

 

 

ACr+2

32–47thbits of y￿

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

For FIR/FIRK

 

 

 

 

 

 

 

 

 

y[k] = Σ m =0..N h[m]x[k–m]

 

 

 

y =

ACr+1

ACr

 

The value of y is stored in ACr and ACr+1 for FIR instruction (32-bit accumulation). COR instruction uses 48-bit accumulation and includes accumulator ACr+2.

Assembly Language Instructions

4-67

Page 153
Image 153
Texas Instruments MSP50C6xx manual Coeffarray address FIRK/CORK only Program memory FIRK/CORK, Coeffarray Samplebuf address