PSB7238 SIEMENS [Siemens Semiconductor Group], PSB7238 Datasheet - Page 67

• Manufacturer Part Number: PSB7238
• Description: Joint Audio Decoder-Encoder - Multimode
• Manufacturer: SIEMENS [Siemens Semiconductor Group]

The following status bits are provided:
XDOV
The HDLC transmitter is controlled by the following bits:
XF
XME
XRES
XNEW
After up to 32 bytes have been written to the FIFO, transmission is started by issuing the
XF command. The opening flag (in the case of HDLC) is generated automatically. The
HDLC controller requests another data block by an XPR interrupt status if there are no
more than 32 bytes in the FIFO and the frame close command bit XME has not been set.
To this the software responds by writing another pool of data and issuing a transmit
command XF for that data. If transmission of earlier data (or of a previous frame) is still
underway when a new transmission command XF is issued, software access to the FIFO
is blocked until the first transmission is completed (see Figure 28).
Semiconductor Group
Transmit Data Overflow
Indicates that more than 32 bytes have been written into the transmit FIFO.
Transmit Frame
Initiates transmission of an entire frame, or part of one (up to 32 bytes).
Transmit Message End
Indicates that after the transmission of data from the FIFO pool, the frame is
to be closed with a closing flag (and possibly a CRC checksum).
Transmitter Reset
Resets the HDLC transmitter, clears the transmit FIFO, aborts any HDLC
frame being transmitted and generates an XPR status after the command
has been completed.
Transmitter Restart
Resets the transmitter state machine without any loss of data (i.e. FIFO
data). The transmission of the current frame can be restarted with the first
bit of the start flag.
67
Data Sheet 1998-07-01
Functional Blocks
PSB 7238