Section 14 Serial Communication Interface (SCI)
Rev. 5.00 May 29, 2006 page 420 of 698
REJ09B0146-0500
The receive margin in the asynchronous mode can therefore be expressed as in equation 1.
Equation 1:
M = 0.5 –
1
2N
D – 0.5
N
– (L – 0.5)F – (1 + F)
×
100%
Where: M
=
Receive margin (
%
)
N
=
Ratio of clock frequency to bit rate (N
=
16)
D
=
Clock duty cycle (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 in equation 2.
Equation 2:
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%.
Cautions for Clock Synchronous External Clock Mode:
•
Set TE = RE = 1 only when the external clock SCK0 is 1.
•
Do not set TE = RE = 1 until at least four clocks after the external clock SCK0 has changed
from 0 to 1.
•
When receiving, RDRF is 1 when RE is set to zero 2.5–3.5 clocks after the rising edge of the
SCK0 input of the D7 bit in RxD0, but it cannot be copied to SCRDR.
Caution for Clock Synchronous Internal Clock Mode: In the receiving, RDRF become 1 when
RE is set to 0, 1.5 clocks after the rising edge of the SCK0 output of the D7 bit in RxD0, but it
cannot be copied to SCRDR.
Summary of Contents for SH7706 Series
Page 8: ...Rev 5 00 May 29 2006 page viii of xlviii ...
Page 160: ...Section 5 Cache Rev 5 00 May 29 2006 page 112 of 698 REJ09B0146 0500 ...
Page 370: ...Section 11 Watchdog Timer WDT Rev 5 00 May 29 2006 page 322 of 698 REJ09B0146 0500 ...
Page 554: ...Section 17 Pin Function Controller PFC Rev 5 00 May 29 2006 page 506 of 698 REJ09B0146 0500 ...
Page 576: ...Section 18 I O Ports Rev 5 00 May 29 2006 page 528 of 698 REJ09B0146 0500 ...
Page 746: ...Index Rev 5 00 May 29 2006 page 698 of 698 REJ09B0146 0500 ...
Page 749: ...SH7706 Group Hardware Manual ...