
535
0
7 8
15 0
7 8
15 0
5
Internal
base clock
Receive
data (RxD)
Synchronization
sampling timing
Data
sampling timing
8 clocks
16 clocks
Start bit
–7.5 clocks
+7.5 clocks
D0
D1
Figure 14.24 Receive Data Sampling Timing in Asynchronous Mode
The receive margin in the asynchronous mode can therefore be expressed as:
M = 0.5 –
1
2N
– L – 0.5 F –
D – 0.5
N
1 + F
100%
(
)
(
)
×
M : Receive margin (%)
N : Ratio of clock frequency to bit rate (N = 16)
D : Clock duty cycle (D = 0–1.0)
L : Frame length (L = 9–12)
F : Absolute deviation of clock frequency
From the equation above, if F = 0 and D = 0.5 the receive margin is 46.875%:
D
= 0.5, F = 0
M = (0.5 – 1/(2
×
16))
×
100%
= 46.875%
This is a theoretical value. A reasonable margin to allow in system designs is 20–30%.
Содержание SH7041 Series
Страница 2: ......
Страница 6: ......
Страница 38: ...xvi ...
Страница 44: ...6 ...
Страница 46: ...8 ...
Страница 48: ...10 ...
Страница 82: ...44 ...
Страница 114: ...76 ...
Страница 118: ...80 ...
Страница 124: ...86 ...
Страница 170: ...132 ...
Страница 250: ...212 ...
Страница 492: ...454 ...
Страница 506: ...468 ...
Страница 604: ...566 ...
Страница 684: ...646 ...
Страница 706: ...668 ...
Страница 778: ...740 ...
Страница 780: ...742 ...
Страница 818: ...780 ...
Страница 850: ...812 ...
Страница 923: ...SH7040 SH7041 SH7042 SH7043 SH7044 SH7045 Group Hardware Manual REJ09B0044 0600O ...