Section 14 Serial Communication Interface with FIFO (SCIF)
Rev. 2.00 Mar 09, 2006 page 633 of 906
REJ09B0292-0200
0 1 2
3 4
5 6 7 8 9 10 11 12 13 14 15 0 1 2
3 4
5 6 7 8 9 10 11 12 13 14 15 0 1 2
3 4
5
Base clock
16 clocks
8 clocks
–7.5 clocks
+7.5 clocks
Start bit
D0
D1
Receive data
(RxD)
Synchronization
sampling timing
Data sampling
timing
Figure 14.25 Receive Data Sampling Timing in Asynchronous Mode
(Using base clock with frequency of 16 times the transfer rate, sampled in 8th clock cycle)
The receive margin in asynchronous mode can therefore be expressed as shown in equation (1).
M = 0.5 –
1
2N
D – 0.5
N
– (L – 0.5) F – (1 + F)
×
100%
................. ............ (1)
M: Receive margin (%)
N: Ratio of clock frequency to bit rate (N = 16, 8, or 4)
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 given by equation (2).
When D = 0.5, F = 0, and N = 16:
M = (0.5 – 1/(2
×
16))
×
100%
= 46.875%...................................................................................................... (2)
This is a theoretical value. A reasonable margin to allow in system designs is 20% to 30%.
When Using Synchronous External Clock Mode
•
Do not set TE or RE to 1 until at least 4 peripheral operating clock cycles after external clock
SCK has changed from 0 to 1.
•
Only set both TE and RE to 1 when external clock SCK is 1.
Содержание SH7616
Страница 10: ...Rev 2 00 Mar 09 2006 page x of xxvi ...
Страница 132: ...Section 2 CPU Rev 2 00 Mar 09 2006 page 106 of 906 REJ09B0292 0200 ...
Страница 568: ...Section 12 16 Bit Free Running Timer FRT Rev 2 00 Mar 09 2006 page 542 of 906 REJ09B0292 0200 ...
Страница 582: ...Section 13 Watchdog Timer WDT Rev 2 00 Mar 09 2006 page 556 of 906 REJ09B0292 0200 ...
Страница 662: ...Section 14 Serial Communication Interface with FIFO SCIF Rev 2 00 Mar 09 2006 page 636 of 906 REJ09B0292 0200 ...
Страница 706: ...Section 16 Serial I O SIO Rev 2 00 Mar 09 2006 page 680 of 906 REJ09B0292 0200 ...
Страница 820: ...Section 19 Pin Function Controller PFC Rev 2 00 Mar 09 2006 page 794 of 906 REJ09B0292 0200 ...
Страница 932: ...Appendix D Package Dimensions Rev 2 00 Mar 09 2006 page 906 of 906 REJ09B0292 0200 ...
Страница 935: ...SH7616 Hardware Manual ...