
PSB 7238
Register Description
Semiconductor Group
116
Data Sheet 1998-07-01
Transmit Command Register XCMD
XF
(Write)
Address 20
H
Bit 7
XF
Bit 0
STX
XCMD
XME
XRES
XNEW
Transmit Frame
Initiates transmission of a pool of data (up to 32 bytes). The XFIFO is write
protected. When the non-accessible part is empty, the contents of the
accessible part is copied to the non-accessible part, an XPR interrupt status
is generated and the accessible part is again writable from the DSP or host
(determined by HAHx bit).
Transmit Message End
Indicates that after the transmission of data from the FIFO pool, the frame is
to be closed with a CRC checksum (programmable) and a closing flag. Can
be set together with XF or as a reaction to the XPR interrupt generated after
the XF for the last FIFO. See
Section 4.3
for details.
Has no meaning in transparent mode.
Transmitter Reset
When XAC = 1, this command 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.
When XRES is issued while XAC = 0, this command initializes in addition
the time-slot count logic for this channel.
Transmitter Restart
When set to ‘1’ during the transmission of the first FIFO (including the start
flag) the transmitter state machine is reset to the starting state without any
loss of data (i.e. FIFO data). XAC is reset to ‘0’ automatically. When XAC is
reprogrammed to ‘1’, the transmission of the current frame is restarted with
the first bit of the start flag.
Start command for TFS generation
Only valid when TFIN = 0 (TFS pulses internally generated) and used if
TCONT bit in TFS mode register is ‘0’.
When TCONT = 0
, when STX is set, exactly TREP(9-0) pulses of one bit
duration and spaced 16 bit periods from each other are generated. When
STX command is given, generation of pulses starts at the next possible
16-bit boundary.
This function may be used in connection with the HDLC controller when a
predefined number of data units (e.g. words) are transmitted, clocked by
TFS pulses.
XME
XRES
XNEW
STX