PEB20571 INFINEON [Infineon Technologies AG], PEB20571 Datasheet - Page 116

• Manufacturer Part Number: PEB20571
• Description: ICs for Communications
• Manufacturer: INFINEON [Infineon Technologies AG]

Preliminary Data Sheet
shared flag mode the HDLCU starts transmitting the message in the frame adjacent to
the reception of the Start transmission command.
Note: Messages with zero byte data content are not supported.
4.6.2.3
When placing the last octet of the message into the Transmit Input Buffer, the DSP
should place an End transmission command in place of the Start transmission command
without changing the CRC bit.
If CRC encoding is required, the CRC vector will be transmitted bit by bit after the octet
of the message, and then a flag will be transmitted. If CRC encoding is not required, a
flag will be transmitted directly after the last octet of the message. Note that in unshared
flag mode, if no adjacent frame exists, ’ones’ will be transmitted after the flag.
4.6.2.4
In order to abort transmission of a message over a dedicated channel, the DSP places
an abort command in the appropriate address in the command RAM. The message
being transmitted over the channel is aborted and ’ones’ are transmitted over the
channel instead (even in the shared flag mode).
4.6.2.5
Reading a channel from the Receive Output Buffer and writing to a channel in the
Transmit Input Buffer is done according to the channel status vector and according to the
Empty and Full procedures as shown below:
Empty procedure
• If the EMPTY flag of a channel is set by the HDLCU to ‘1’, then move a new time slot
• If the pipe is empty change the pipe page and ask for the next 16 bytes of data from
Note: The B-channel buffer may be emptied within a single frame, while it takes at least
Full procedure
• If the FULL flag of a channel is set by the HDLCU to ‘1’ then the DSP moves the time
• If the pipe is full change the pipe page and transfer the next 16 bytes of data to the
Note: The B-channel buffer may be filled within a single frame, while a D-channel buffer
to be transmitted from the pipe to the Transmit Input Buffer.
the external controller by means of DMA or interrupt.
slot from the Receive Output Buffer into the double buffer.
External Controller by means of DMA or interrupt.
4 frames to empty a D-channel buffer.
will take at least 4 frames to fill.
Ending a Transmission
Aborting a Transmission
DSP Access to the HDLCU Buffers
4-32
Functional Description
DELIC
2003-08