Intel SA-1100 manual SDSR1, Ror Cre Eof Rtd Tnf Rne, Rsy, Tby

Peripheral Control Module

The following table shows the location of the flag and status bits within SDLC status register 1. The bits within this register do not produce interrupt requests. Note that the reset value of RTD is unknown (indicated by question marks) and must be cleared if set following a reset of the SA-1100. The remainder of SDSR1 is read-only (writes are ignored).

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	Address: 0h 8002 0084				SDSR1		Read/Write & Read-Only
Bit	7		6	5	4	3	2	1	0
		ROR	CRE	EOF	RTD	TNF	RNE	TBY	RSY
Reset	0		0	0	?	1	0	0	0

Bit	Name		Description
0	RSY	Receiver synchronized flag (read-only).
		0	– Receiver is in hunt mode or is disabled.
		1	– Receiver logic is synchronized with the incoming data (no interrupt generated).
1	TBY	Transmitter busy flag (read-only).
		0	– Transmitter is idle (continuous flags) or disabled.
		1– Transmit logic is currently transmitting a frame (address, control, data, CRC, or
		start/stop flag) or an abort (no interrupt generated).
2	RNE	Receive FIFO not empty (read-only).
		0	– Receive FIFO is empty.
		1	– Receive FIFO is not empty (no interrupt generated).
3	TNF	Transmit FIFO not full (read-only).
		0	– Transmit FIFO is full.
		1	– Transmit FIFO is not full (no interrupt generated).
4	RTD	Receive transition detect.
		0	– No transition detected on RXD1 pin since the last time software cleared this bit.
		1	– Rising and/or falling edge detected on RXD1 pin (no interrupt generated).
5	EOF	End of frame (read-only).
		0	– Current frame has not completed.
		1	– The value at the bottom of the receive FIFO is the last byte of data within the frame.
6	CRE	CRC error (read-only).
		0	– No CRC check errors encountered in the receipt of data.
		1	– CRC calculated on the incoming data does not match CRC value contained within
		the received frame.
7	ROR	Receive FIFO overrun (read-only).
		0	– Receive FIFO has not experienced an overrun.
		1	– Receive logic attempted to place data into receive FIFO while it was full; the next
		data value in the FIFO is the last piece of “good” data before the FIFO was overrun.

SA-1100 Developer’s Manual 11-101