SD16 Operation
27-9
SD16
Digital Filter Output
The number of bits output by each digital filter is dependent on the
oversampling ratio and ranges from 16 to 24 bits. Figure 27−5 shows the
digital filter output bits and their relation to SD16MEMx for each OSR. For
example, for OSR = 256 and LSBACC = 0, the SD16MEMx register contains
bits 23 − 8 of the digital filter output. When OSR = 32, the SD16MEMx LSB is
always zero.
The SD16LSBACC and SD16LSBTOG bits give access to the least significant
bits of the digital filter output. When SD16LSBACC = 1 the 16 least significant
bits of the digital filter’s output are read from SD16MEMx using word
instructions. The SD16MEMx register can also be accessed with byte
instructions returning only the 8 least significant bits of the digital filter output.
When SD16LSBTOG = 1 the SD16LSBACC bit is automatically toggled each
time the corresponding channel’s SD16MEMx register is read. This allows the
complete digital filter output result to be read with two read accesses of
SD16MEMx. Setting or clearing SD16LSBTOG does not change
SD16LSBACC until the next SD16MEMx access.
Figure 27−5. Used Bits of Digital Filter Output.
0
4
8
12
16
20
1
5
3
2
6
9
7
23 22 21
19 18 17
15 14 13
11 10
OSR=32, LSBACC=x
0
4
8
12
16
20
1
5
3
2
6
9
7
23 22 21
19 18 17
15 14 13
11 10
OSR=64, LSBACC=1
0
4
8
12
16
20
1
5
3
2
6
9
7
23 22 21
19 18 17
15 14 13
11 10
OSR=64, LSBACC=0
0
4
8
12
16
20
1
5
3
2
6
9
7
23 22 21
19 18 17
15 14 13
11 10
OSR=128, LSBACC=1
0
4
8
12
16
20
1
5
3
2
6
9
7
23 22 21
19 18 17
15 14 13
11 10
OSR=128, LSBACC=0
0
4
8
12
16
20
1
5
3
2
6
9
7
23 22 21
19 18 17
15 14 13
11 10
OSR=256, LSBACC=1
0
4
8
12
16
20
1
5
3
2
6
9
7
23 22 21
19 18 17
15 14 13
11 10
OSR=256, LSBACC=0
Summary of Contents for MSP430x4xx Family
Page 1: ...MSP430x4xx Family 2007 Mixed Signal Products User s Guide SLAU056G ...
Page 2: ......
Page 6: ...vi ...
Page 114: ...3 76 RISC 16 Bit CPU ...
Page 304: ...5 20 FLL Clock Module ...
Page 340: ...7 8 Supply Voltage Supervisor ...
Page 348: ...8 8 16 Bit Hardware Multiplier ...
Page 372: ...9 24 32 Bit Hardware Multiplier ...
Page 400: ...10 28 DMA Controller ...
Page 428: ...13 10 Basic Timer1 ...
Page 466: ...15 24 Timer_A ...
Page 522: ...17 30 USART Peripheral Interface UART Mode ...
Page 544: ...18 22 USART Peripheral Interface SPI Mode ...
Page 672: ...23 12 Comparator_A ...
Page 692: ...24 20 LCD Controller ...
Page 746: ...26 28 ADC12 ...