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R01UH0336EJ0102 Rev.1.02
Page 1263 of 1538
Jul 17, 2014
V850E2/PG4-L
Section 22 Synchronous/Asynchronous Serial Interface H (UARTH)
22.6.12
UARTHn reception
Reception
start
Set the reception enabled status by the following procedure:
• Specify the baud rate by the UARTHn control register 2 (URTHnCTL2).
• Specify the receive parity, data character length, receive data order, and
output logic level of receive data by the UARTHn control register 1
(URTHnCTL1).
• Enable UARTHn operation and reception by setting
URTHnCTL0.URTHnPW = URTHnCTL0.URTHnRXE = 1.
When the sampling of the input level of the URTHnTRXD pin is performed and
the falling edge is detected, the data sampling of the URTHnRXD input is
started.
The start bit is recognized if the URTHnRXD pin is low level after the time of a
half bit is passed after the detection of the falling edge (shown in the figure
below).
After a start bit has been recognized, the receive operation starts, and serial
data are stored in the reception shift register according to the set baud rate.
When the reception interrupt URTHnTIR is asserted upon reception of the stop
bit, the data stored in the reception shift register are written to the receive data
register (URTHnRX).
Reception
stop
When URTHnCTL0.URTHnPW or URTHnCTL0.URTHnRXE is set to 0,
reception operations are stopped immediately, even during reception
processing.
Reception
errors
If an overrun error occurs (URTHnSTR1.URTHnOVE = 1), the receive data at
this time is not transferred to the URTHnRX register and is discarded.
Even if a parity error (URTHnSTR1.URTHnPE = 1) occurs during reception,
reception continues until the stop bit, and the reception data are transferred to
the RX register. And, a framing error (URTHnSTR1.URTHnFE = 1) is judged at
the stop bit position, and even if an error is detected, the received date is
transferred to the URTHnRX register.
An error in reception in this case leads to generation of the status interrupt
(URTHnTIS) instead of the reception interrupt (URTHnTIR).
Clear the power bit to 0 (URTHnCTL0.URTHnPW = 0) before changing the
order of data reception, parity, character length, or logic level of receive data.
Figure 22-15
UARTHn Reception
D0
D1
D2
D3
D4
D5
D6
D7
URTHnTIR
URTHnRX
Start
bit
Parity
bit
Stop bit
Содержание V850 Series
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