
PSB 7280
Semiconductor Group
122
Data Sheet 1998-07-01
This byte is the same as the byte appended in the RFIFO to the last byte (or CRC) of the
frame. The value is updated after the end flag has been received and before RSTA is
written to the RFIFO and RME interrupt status is generated.
The status register is completely reset with every start flag. Thus, the DSP/host should
always use the RSTA value from the RFIFO to evaluate the status at the end of the
corresponding frame, since the register contents does not necessarily refer to the current
frame being read from the RFIFO.
Has no meaning in transparent mode.
Receive Status Register
RSTA
Read
Address 21
H
Bit 7
Bit 0
RSTA
VFR
RDO
CRC
RAB
VFR
Valid Frame
Indicates whether the frame length is valid (1) or not (0).
Set: If the frame length (transparent data without zero insertion) is a multiple
of 8 bits and the frame contains at least 16 bits.
Reset: All other frame lengths, with every new start flag
Receive Data Overflow
At least one byte of the frame has been lost because it could not be stored
in the FIFO.
Set:
When one byte of frame data is available from the HDLC bitengine
but cannot be stored in the RFIFO because it’s full.
Reset: With every new start flag
CRC check
Correct (1) or incorrect (0). The value is updated after the end flag has been
received and before RSTA is written to the RFIFO and RME interrupt status
is generated.
Set:
CRC correct
Reset: CRC incorrect, with every new start flag
Receive Message Aborted
Frame aborted by the remote station (7 consecutive ‘1’s received), yes (1)
or no (0).
Set:
After 7 consecutiv ‘1’s have been received
Reset: With every new start flag
RDO
CRC
RAB