CHAPTER 10 SERIAL INTERFACE FUNCTION
User’s Manual U15195EJ5V0UD
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(4) 2-frame continuous reception buffer register 1 (RXB1)/receive buffer register L1 (RXBL1)
The RXB1 register is a 16-bit buffer register that holds receive data (during 2-frame continuous reception
(UMSR bit of ASIM11 register = 1), during 9-bit extended data reception (EBS bit of ASIM11 register = 1)).
During 7 or 8 bit character reception, 0 is stored in the MSB.
For 16-bit access to this register, specify RXB1, and for access to the lower 8 bits, specify RXBL1.
In the receive enabled status, receive data is transferred from the receive shift register to the reception buffer
in synchronization with the end of shift-in processing for 1 frame of data.
The reception completion interrupt request (INTSR1) is generated upon transfer of data to the reception
buffer (when 2-frame reception is specified, reception buffer transmission of the second frame).
In the reception disabled status, transfer processing to the reception buffer is not performed even if shift-in
processing for 1 frame of data has been completed, and the contents of the reception buffer are held.
Neither is a reception completion interrupt request generated.
The RXB1 register can be read in 16-bit units, and the RXBL1 register can be read in 8-bit units.
14
RXB14
13
RXB13
12
RXB12
2
RXB2
3
RXB3
4
RXB4
5
RXB5
6
RXB6
7
RXB7
8
RXB8
9
RXB9
10
RXB10
11
RXB11
15
RXB15
1
RXB1
0
RXB0
RXB1
[2-frame continuous reception buffer register 1]
Address
FFFFFA20H
After reset
Undefined
2
RXB2
3
RXB3
4
RXB4
5
RXB5
6
RXB6
7
RXB7
1
RXB1
0
RXB0
RXBL1
[Receive buffer register L1]
Address
FFFFFA22H
After reset
Undefined
Bit position
Bit name
Function
15 to 0
RXB15 to
RXB0
Stores receive data.
0 can be read for the RXB1 register when 7 or 8 bit character data is received.
When an extension bit is set during 9 bit character data reception, the extension bit
(RXB8) is stored in RB8 of the ASIS1 register simultaneously with saving to the
reception buffer.
0 can be read for the RXB7 bit of the RXBL1 register during 7 bit character data
reception.