DF2148BTE20 Renesas Electronics America, DF2148BTE20 Datasheet - Page 434

• Manufacturer Part Number: DF2148BTE20
• Description: IC H8S MCU FLASH 128K 100-QFP
• Manufacturer: Renesas Electronics America
• Series: H8® H8S/2100r

Specifications of DF2148BTE20

• Core Processor: H8S/2000
• Core Size: 16-Bit
• Speed: 20MHz
• Connectivity: I²C, IrDA, SCI, X-Bus
• Peripherals: PWM, WDT
• Number Of I /o: 74
• Program Memory Size: 128KB (128K x 8)
• Program Memory Type: FLASH
• Ram Size: 4K x 8
• Voltage - Supply (vcc/vdd): 4.5 V ~ 5.5 V
• Data Converters: A/D 8x10b; D/A 2x8b
• Oscillator Type: Internal
• Operating Temperature: -20°C ~ 75°C
• Package / Case: 100-TQFP, 100-VQFP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Eeprom Size: -
• Other names: HD64F2148BTE20; HD64F2148BTE20

Section 15 Serial Communication Interface (SCI and IrDA)
15.4.2
In asynchronous mode, the SCI operates on a basic clock with a frequency of 16 times the bit rate.
In reception, the SCI samples the falling edge of the start bit using the basic clock, and performs
internal synchronization. Since receive data is latched internally at the rising edge of the 8th pulse
of the basic clock, data is latched at the middle of each bit, as shown in figure 15.3. Thus the
reception margin in asynchronous mode is determined by formula (1) below.
Assuming values of F = 0 and D = 0.5 in formula (1), the reception margin is determined by the
formula below.
However, this is only the computed value, and a margin of 20% to 30% should be allowed in
system design.
Rev. 3.00 Mar 21, 2006 page 378 of 788
REJ09B0300-0300
Internal
basic clock
Receive data
(RxD)
Synchronization
sampling timing
Data sampling
timing
M = (0.5 –
M = {0.5 – 1/(2 × 16)} × 100
Receive Data Sampling Timing and Reception Margin in Asynchronous Mode
}
M: Reception margin (%)
N : Ratio of bit rate to clock (N = 16)
D : Clock duty (D = 0.5 to 1.0)
L : Frame length (L = 9 to 12)
F : Absolute value of clock rate deviation
Figure 15.3 Receive Data Sampling Timing in Asynchronous Mode
2N
1
0
) –
8 clocks
Start bit
D – 0.5
N
16 clocks
(1 + F) – (L – 0.5) F } × 100
7
[%] = 46.875 %
15 0
D0
[%]
... Formula (1)
7
15 0
D1