HD6475328-CP10 HITACHI [Hitachi Semiconductor], HD6475328-CP10 Datasheet - Page 285

• Manufacturer Part Number: HD6475328-CP10
• Description: original Hitachi CMOS microcomputer unit (MCU)
• Manufacturer: HITACHI [Hitachi Semiconductor]

Table 14-10 SSR Bit States and Data Transfer When Multiple Receive Errors Occur
Receive Error
Overrun error
Framing error
Parity error
Overrun + framing errors
Overrun + parity errors
Framing + parity errors
Overrun + framing + parity errors
*1 Set to 1 before the overrun error occurs.
*2 Yes: The RSR contents are transferred to the RDR.
3. Line Break Detection: When the RXD pin receives a continuous stream of 0’s in the
4. Sampling Timing and Receive Margin in Asynchronous Mode: The serial clock used by
asynchronous mode (line-break state), a framing error occurs because the SCI detects a 0 stop
bit. The value H'00 is transferred from the RSR to the RDR. Software can detect the line-
break state as a framing error accompanied by H'00 data in the RDR.
The SCI continues to receive data, so if the FER bit is cleared to 0 another framing error will
occur.
the SCI in asynchronous mode runs at 16 times the bit rate. The falling edge of the start bit is
detected by sampling the RXD input on the falling edge of this clock. After the start bit is
detected, each bit of receive data in the frame (including the start bit, parity bit, and stop bit or
bits) is sampled on the rising edge of the serial clock pulse at the center of the bit.
See figure 14-5.
It follows that the receive margin can be calculated as in equation (1).
When the absolute frequency deviation of the clock signal is 0 and the clock duty factor is 0.5,
data can theoretically be received with distortion up to the margin given by equation (2). This
is a theoretical limit, however. In practice, system designers should allow a margin of 20% to
30%.
No: The RSR contents are not transferred to the RDR.
RDRF
1
0
0
1
1
0
1
*1
*1
*1
*1
270
ORER
1
0
0
1
1
0
1
SSR Bits
FER
0
1
0
1
0
1
1
PER
0
0
1
0
1
1
1
RSR to RDR
No
Yes
Yes
No
No
Yes
No
*2