mcs7717 MosChip, mcs7717 Datasheet - Page 23

• Manufacturer Part Number: mcs7717
• Description: Three Port Usb Hub With 1 Serial, 1 Printer
• Manufacturer: MosChip

Rev. 1.7
Line Status Register:
This register provides the status of the data transfer to the CPU.
Register:
Description:
Offset:
Permissions:
Access Condition:
Note : A break condition occurs when the SIN line goes low and stays low through out the start, data, parity
& first stop bits. One zero character associated with break flag set will be transferred to the RHR and the
receiver will then wait until the SIN line returns high. The LSR[4] flag break flag is set when this data item
gets to the top of the RHR and it is cleared following the read to the LSR.
Bit
0
1
2
3
4
5
6
7
Bit[7]
Error
Data
Transmitter & THR
Received Break
Received Data
Received Data
Data Available
Receiver Data
Framing Error
Parity Error
Overrun
Empty
Empty
LSR
Line Status Register
101
Read
LCR[7] =0, ACR[6] = 0
Name
Error
Error
RHR
RHR
Empty
THR
Bit[6]
Tx
Logic 0 = RHR is empty
Logic 1 = RHR is not empty, data is available to be read
Logic 0 = No overrun error
Logic 1 = Data was received when the RHR was full, An overrun
Logic 0 = No parity error in received data, or 9th bit is “0” in 9-bit
Logic 1 = Data has been received that did not have correct parity
Logic 0 = No framing error
Logic 1 = data has been received with an invalid stop bit.
Logic 0 = No receiver break error
Logic 1 = the receiver received a break error
Logic 0 = Transmitter FIFO is not empty
Logic 1 = Transmitter FIFO is empty
Logic 0 = The transmitter is not idle
Logic 1 = THR is empty & the transmitter has completed the character
Logic 0 = Either there are no receiver data errors in the FIFO, or it
Logic 1 = At least one parity error, framing error or break indication in
Empty
Bit[5]
THR
has occurred. The error is flagged when the data would
normally have been transferred to the RHR.
mode.
in the shift register and is in the idle mode
was cleared by earlier read of LSR
the FIFO.
Break
Bit[4]
Rx
Three Port USB Hub with 1 Serial, 1 Printer
Framing
Bit[3]
Error
Description
Bit[2]
Parity
Error
MCS7717
Overrun
Bit[1]
Page 23
RxRdy
Bit[0]