Section 12 Serial Communication Interface (SCI)
Rev. 3.00 Sep. 27, 2007 Page 473 of 758
REJ09B0243-0300
0 1 2 3 4 5 6 7 8 9 10 1112 1314 15 0 1 2 3 4 5 6 7 8 9 10 1112 1314 15 0 1 2 3 4 5
D0
D1
16 clocks
8 clocks
Base clock
Receive data
(RXD)
Start bit
–7.5 clocks
+7.5 clocks
Synchronization
sampling timing
Data sampling
timing
Figure 12.21 Receive Data Sampling Timing in Asynchronous Mode
The receive margin in asynchronous mode can therefore be expressed as shown in equation 1.
Equation 1:
M = (0.5 - ) - (L - 0.5) F -
(1+F)
×
100 %
1
2N
D - 0.5
N
Where: M: Receive margin (%)
N: Ratio of bit rate to clock (N = 16)
D: Clock duty (D = 0 to 1.0)
L: Frame length (L = 9 to 12)
F: Absolute deviation of clock frequency
From equation 1, if F = 0 and D = 0.5, the receive margin is 46.875%, as given by equation 2.
Equation 2:
When D = 0.5 and 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% to 30%.
Summary of Contents for SH7124 R5F7124
Page 2: ...Rev 3 00 Sep 27 2007 Page ii of xx ...
Page 8: ...Rev 3 00 Sep 27 2007 Page viii of xx ...
Page 36: ...Section 1 Overview Rev 3 00 Sep 27 2007 Page 16 of 758 REJ09B0243 0300 ...
Page 68: ...Section 2 CPU Rev 3 00 Sep 27 2007 Page 48 of 758 REJ09B0243 0300 ...
Page 108: ...Section 5 Exception Handling Rev 3 00 Sep 27 2007 Page 88 of 758 REJ09B0243 0300 ...
Page 166: ...Section 7 User Break Controller UBC Rev 3 00 Sep 27 2007 Page 146 of 758 REJ09B0243 0300 ...
Page 724: ...Section 20 List of Registers Rev 3 00 Sep 27 2007 Page 704 of 758 REJ09B0243 0300 ...
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Page 778: ...Rev 3 00 Sep 27 2007 Page 758 of 758 REJ09B0243 0300 ...
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