CHAPTER 19 SERIAL INTERFACE UNIT 1 (SIU1)
User’s Manual U14272EJ3V0UM
373
19.3.10 SIULS_1 (0x0C00 0015)
Bit
7
6
5
4
3
2
1
0
Name
LSR7
LSR6
LSR5
LSR4
LSR3
LSR2
LSR1
LSR0
R/W
R
R
R
R
R
R
R
R
RTCRST
0
1
1
0
0
0
0
0
Other resets
0
1
1
0
0
0
0
0
Bit
Name
Function
7
LSR7
Error detection (FIFO mode)
1 : Parity error, framing error, or break is detected.
0 : No error
6
LSR6
Transmit block empty
1 : No data in transmit holding register and transmit shift register
No data in transmit FIFO (during FIFO mode)
0 : Data exists in transmit holding register or transmit shift register
Data exists in transmit FIFO (during FIFO mode)
5
LSR5
Transmit holding register empty
1 : Character is transferred to transmit shift register (during 16450 mode)
Transmit FIFO is empty (during FIFO mode)
0 : Character is stored in transmit holding register (during 16450 mode)
Transmit data exists in transmit FIFO (during FIFO mode)
4
LSR4
Break interrupt
1 : Detected
0 : No break
3
LSR3
Framing error
1 : Detected
0 : No error
2
LSR2
Parity error
1 : Detected
0 : No error
1
LSR1
Overrun error
1 : Detected (receive data is overwritten)
0 : No error
0
LSR0
Receive data ready
1 : Receive data exists in FIFO
0 : No receive data in FIFO
The CPU uses this register to get information related to data transfers.
When LSR7 and LSR(4:1) bits are 1, reading this register clears these bits to 0.
Caution
The LSR0 bit (receive data ready bit) is set before the serial data reception is completed.
Therefore, the LSR0 bit may not be cleared if the serial receive data is read from the SIURB_1
register immediately after this bit is set.
When reading data from the SIURB_1 register, wait for the stop bit width time since the LSR0 bit
is set.