H8S2245 datasheet(508/818 Pages) RENESAS

Part #	H8S2245

Description	Renesas 16-Bit Single-Chip Microcomputer H8S Family / H8S/2200 Series

PDF	818 Pages

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Manufacturer	RENESAS [Renesas Technology Corp]

Direct Link	http://www.renesas.com

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508 / 818 page

Section 12 Serial Communication Interface (SCI)

Rev.3.00 Mar. 26, 2007 Page 466 of 772

REJ09B0355-0300

Internal basic

clock

16 clocks

8 clocks

Receive data

(RxD)

Synchronization

sampling timing

Start bit

Data sampling

timing

15 0

Figure 12.21 Receive Data Sampling Timing in Asynchronous Mode

Thus the reception margin in asynchronous mode is given by formula (1) below.

M = | (0.5 –

) – (L – 0.5) F –

| D – 0.5 |

(1 + F) |

× 100%

... Formula (1)

Where M: Reception 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)

Absolute value of clock rate deviation

Assuming values of F = 0 and D = 0.5 in formula (1), a reception margin of 46.875% is given by

formula (2) below.

When D = 0.5 and F = 0,

M = (0.5 –

× 16

) × 100%

= 46.875%

... Formula (2)

However, this is only the computed value, and a margin of 20% to 30% should be allowed in

system design.

H8S2245 Datasheet(PDF) 508 Page - Renesas Technology Corp