
Decimation Filter
MPC5644A Microcontroller Reference Manual, Rev. 6
1208
Freescale Semiconductor
Figure 26-18. Filter configuration paths (FIR or 1x4 poles IIR)
26.5.6.1
Rounding
The Decimation Filter performs rounding operations in two different locations, as shown in
:
•
to obtain the filter output result with 16 bits
•
to obtain the IIR feedback result to be stored in tap4 registers with 24 bits
The rounding mechanism implements the Convergent Rounding methodology (also known as
round-to-nearest even number), which makes the decision on rounding up or down based on the value of
the lower portion of data to be rounded (LS_WORD). The rounding up/down condition is equal to the
traditional rounding except when the LS_WORD has the format {1000...00}. In this particular case, the
rounding procedure is like the example of
. If the MS_WORD is odd, the value is rounded
up. Otherwise the value is rounded down.
By-pas
FI
Z
-1
Z
-1
Z
-1
Z
-1
+
Coefficient 2
Tap1
Coefficient 4
Coefficient 3
Tap2
Tap3
Tap0
Coefficient 1
x(n)
+
Coefficient 6
Tap5
Coefficient 8
Coefficient 7
Tap6
Tap7
Tap4
Coefficient 5
y(n)
01
10
B
Z
-1
Z
-1
Z
-1
Z
-1
Round/Sat
FTYPE[1:0]
Round/Sat
IIR
00
A
Scale Factor S
Register
Coefficient 0
FIR Section
IIR Section
Содержание MPC5644A
Страница 2: ...MPC5644A Microcontroller Reference Manual Rev 6 2 Freescale Semiconductor...
Страница 24: ...MPC5644A Microcontroller Reference Manual Rev 6 24 Freescale Semiconductor...
Страница 26: ...MPC5644A Microcontroller Reference Manual Rev 6 26 Freescale Semiconductor...
Страница 52: ...Introduction MPC5644A Microcontroller Reference Manual Rev 6 52 Freescale Semiconductor...
Страница 56: ...Memory Map MPC5644A Microcontroller Reference Manual Rev 6 56 Freescale Semiconductor...
Страница 130: ...Device Performance Optimization MPC5644A Microcontroller Reference Manual Rev 6 130 Freescale Semiconductor...
Страница 204: ...Multi Layer AHB Crossbar Switch XBAR MPC5644A Microcontroller Reference Manual Rev 6 204 Freescale Semiconductor...
Страница 212: ...Peripheral Bridge PBRIDGE MPC5644A Microcontroller Reference Manual Rev 6 212 Freescale Semiconductor...
Страница 558: ...System Integration Unit SIU MPC5644A Microcontroller Reference Manual Rev 6 558 Freescale Semiconductor...
Страница 582: ...Frequency modulated phase locked loop FMPLL MPC5644A Microcontroller Reference Manual Rev 6 582 Freescale Semiconductor...
Страница 766: ...Enhanced Time Processing Unit eTPU2 MPC5644A Microcontroller Reference Manual Rev 6 766 Freescale Semiconductor...
Страница 1228: ...Decimation Filter MPC5644A Microcontroller Reference Manual Rev 6 1228 Freescale Semiconductor...
Страница 1236: ...System Information Module and Trim SIM MPC5644A Microcontroller Reference Manual Rev 6 1236 Freescale Semiconductor...
Страница 1250: ...Cyclic Redundancy Checker CRC Unit MPC5644A Microcontroller Reference Manual Rev 6 1250 Freescale Semiconductor...
Страница 1336: ...Deserial Serial Peripheral Interface DSPI MPC5644A Microcontroller Reference Manual Rev 6 1336 Freescale Semiconductor...
Страница 1388: ...Enhanced Serial Communication Interface ESCI MPC5644A Microcontroller Reference Manual Rev 6 1388 Freescale Semiconductor...
Страница 1440: ...FlexCAN Module MPC5644A Microcontroller Reference Manual Rev 6 1440 Freescale Semiconductor...
Страница 1624: ...FlexRay Communication Controller FlexRay MPC5644A Microcontroller Reference Manual Rev 6 1624 Freescale Semiconductor...
Страница 1670: ...JTAG Controller JTAGC MPC5644A Microcontroller Reference Manual Rev 6 1670 Freescale Semiconductor...
Страница 1692: ...Nexus Port Controller NPC MPC5644A Microcontroller Reference Manual Rev 6 1692 Freescale Semiconductor...
Страница 1701: ...Development Trigger Semaphore DTS MPC5644A Microcontroller Reference Manual Rev 6 Freescale Semiconductor 1701...
Страница 1702: ...Development Trigger Semaphore DTS MPC5644A Microcontroller Reference Manual Rev 6 1702 Freescale Semiconductor...