
V PeRiPheRaL MoDuLes 3 (inteRFaCe): GeneRaL-PuRPose seRiaL inteRFaCe (eFsio)
s1C33L17 teChniCaL ManuaL
ePson
V-1-23
V
EFSIO
Example: Data length: 8 bits, Stop bit: 1 bit, Parity bit: Included
S1
S2
Start bit
Stop bit
P
A
Parity bit
First data is read.
Receive-buffer full interrupt request
(FIFOINTx[1:0] = 2)
Overrun error
interrupt request
Sampling clock
SINx
Receive data buffer
RXDxNUM[1:0]
RDBFx
data 1
S1 D0 P S2 S1 D0 P S2 S1 D0 P S2 S1 D0 P S2 S1 D0 P S2 S1 D0 P S2
data 2
data 3
data 4
data 5
data 6
A
data 1
1, 2
2, 3, 4, 5
2, 3, 4
1, 2, 3
2, 3
1
3
2
1
0
Figure V.1.4.3.2 Receive Timing Chart in Asynchronous Mode
1. The serial interface starts sampling when the start bit is input (SINx = low).
2. When the start bit is sampled at the first rising edge of the sampling clock, each bit of receive data is taken
into the shift register, beginning with the LSB at each rising edge of the subsequent clock. This operation is
repeated until the MSB of data is received.
3. When the MSB is taken in, the parity bit that follows is also taken in (if EPRx = 1).
4. When the stop bit is sampled, the data in the shift register is transferred to the receive data register, enabling
the data to be read out.
The parity is checked when data is transferred to the receive data register (if EPRx = 1).
note: The receive operation is terminated when the first stop bit is sampled even if the stop bit is config-
ured with two bits.
(3) Receive errors
Three types of receive errors can be detected when receiving data in the asynchronous mode.
Since an interrupt can be generated by setting the interrupt controller, the error can be processed using an inter-
rupt processing routine. For details on receive error interrupts, refer to Section V.1.7, “Serial Interface Interrupts
and DMA.”
Parity error
If EPRx (D5/0x300Bx3) is set to 1 (parity added), the parity is checked when data is received.
This parity check is performed when the data received in the shift register is transferred to the receive data buf-
fer in order to check conformity with PMDx (D4/0x300Bx3) settings (odd or even parity).
PMDx: Serial I/F Ch.x Parity Mode Select Bit in the Serial I/F Ch.x Control Register (D4/0x300Bx3)
If any nonconformity is found in this check, a parity error is assumed and the parity error flag PERx (D3/
0x300Bx2) is set to 1.
PeRx: Serial I/F Ch.x Parity Error Flag in the Serial I/F Ch.x Status Register (D3/0x300Bx2)
Even when this error occurs, the received data in error is transferred to the receive data buffer and the receive
operation is continued. However, the content of the received data for which a parity error is flagged cannot be
guaranteed.
PERx (D3/0x300Bx2) is reset to 0 by writing 0.