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CHAPTER 15 SERIAL INTERFACE UART2
301
User
’
s Manual U14260EJ3V1UD
(c) Reception
The interface enters the reception wait status if the multi-processor transfer mode is specified by using
transfer mode specification register 2 (TRMC2) and bit 7 (POWER2) of asynchronous serial interface mode
register 2 (ASIM2) is set to 1 and then bit 5 (RXE2) is set to 1. In this status, the R
X
D2 pin is monitored
to detect the start bit. When the start bit is detected, reception is started, and serial data is sequentially
stored in receive shift register 2 (RX2) at the specified baud rate.
If data with the multi-processor appended bit set to
“
1
”
is received (ID reception), a receive completion
interrupt (INTSR2) occurs after the stop bit has been detected and, at the same time, the data in RX2 is written
to receive buffer register 2 (RXB2). At this time, bit 3 (MPR2) of asynchronous serial interface register 2
(ASIS2) is set to 1. After it has been confirmed that MPR2 is 1, the ID of the receive data and the ID of
the microprocessor are compared (for which software processing is necessary). If the two IDs match, the
interface prepares for the next reception and waits for the next receive completion interrupt (INTSR2). If
the IDs do not match, clear bit 1 (MPIEN2) of transfer mode specification register 2 (TRMC2) to 0. This makes
receive data other than ID invalid and prevents occurrence of an unwanted receive completion interrupt
(INTSR2).
Figure 15-22. Timing of Receive Completion Interrupt Request in Multi-Processor Transfer Mode (1/2)
(1) If receive data matches ID
D0
Start
Start
Stop
Start
Stop
D7
…
…
MPR2
MPR2
D0
D7
D0
FF
Data 1 (ID)
Data 2 (data)
RxD2 (input)
INTSR2
RXB2
MPIEN2
CPU
MPR2
MPR2
→
1
RXB2
→
data 1 (ID)
RXB2
→
data 2 (data)
1
IDs match. Prepares for reception and
waits for INTSR2.
ID receive frame
Data receive frame