GD32W51x User Manual
371
Figure 14-10. 20-bit to 16-bit result truncation
Raw 20-bit data
19
15
11
7
3
0
15
11
7
3
0
Shifting
Truncation
and rounding
Note:
If the intermediate result after the shifting exceeds 16 bits, the upper bits of the result
are simply truncated.
Figure 14-11. A numerical example with 5-bit shifting and rounding
shows a numerical
example of the processing, from a raw 20-bit accumulated data to the final 16-bit result.
Figure 14-11. A numerical example with 5-bit shifting and rounding
2
A
C
D
6
Raw 20-bit data
19
15
11
7
3
0
1
5
6
6
15
11
7
3
0
Final result after 5-bit shift
and rounding to nearest
Table 14-6. Maximum output results for N and M combimations (grayed values
indicates truncation)
below gives the data format for the various N and M combinations, and
the raw conversion data equals 0xFFF.
Table 14-6. Maximum output results for N and M combimations (grayed values
indicates truncation)
Oversa
m pling
ratio
Max
Raw
data
No-shift
OVSS=
0000
1-bit
shift
OVSS=
0001
2-bit
shift
OVSS=
0010
3-bit
shift
OVSS=
0011
4-bit
shift
OVSS=
0100
5-bit
shift
OVSS=
0101
6-bit
shift
OVSS=
0110
7-bit
shift
OVSS=
0111
8-bit
shift
OVSS=
1000
2x
0x1FFE 0x1FFE 0x0FFF 0x07FF 0x03FF 0x01FF 0x00FF 0x007F 0x003F 0x001F
4x
0x3FFC 0x3FFC 0x1FFE 0x0FFF 0x07FF 0x03FF 0x01FF 0x00FF 0x007F 0x003F
8x
0x7FF8 0x7FF8 0x3FFC 0x1FFE 0x0FFF 0x07FF 0x03FF 0x01FF 0x00FF 0x007F
16x
0xFFF0 0xFFF0 0x7FF8 0x3FFC 0x1FFE 0x0FFF 0x07FF 0x03FF 0x01FF 0x00FF