Low Level Controller
6.3
LLC Code Elements
Structures
6.3.1
The Structure ’PEITAB’
As the various routines in the LLC require facilities to store information about the device they
control, information structures have been introduced. One of these structures is named
PEITAB. A variable of type PEITAB contains all relevant information about the HDLC controller
and L1 part. The LLC uses the external function GetPEITAB_BASIC to get a pointer to the
corresponding PEITAB variable. The following section deals with the important elements of
PEITAB.
Status Information
pt_op_mode
operating mode of the ISAC-S HDLC controller (auto-mode, non-
auto-mode…)
pt_state
Flags of 'pt_state' indicate the various device states.
pt_ModulMode hardware configuration (TE or NT-S)
I/O buffer related elements
These elements are used when the HDLC data is transmitted or received. In both the transmit
and receive directions additional RAM is required to store data on an intermediate basis. This
buffer will be referred to as the data frame. Related information is stored in the following
elements:
Transmit buffer pointers
pt_tx_start
pt_tx_curr
pointer to the starting point of the data frame for transmission
pointer to the present byte to be sent
Receive buffer pointers
pt_rx_start
pt_rx_curr
pointer to the starting point of the receive data frame.
pointer to the next free position in the receive buffer.
Data byte counters
pt_tx_cnt
pt_rx_cnt
number of bytes yet to be transmitted
number of bytes currently received
The following elements are used to store the type of frame:
pt_rx_frame
pt_tx_frame
type of received frame.
type of transmitted frame.
Register addresses are contained in those structure elements which have the prefix pt_r
followed by the register mnemonic. For example pt_r_fifo contains the address of the ISAC-S
XFIFO/RFIFO, pt_r_mode the address of the ISAC-S MODE register, etc.
Semiconductor Group
277
INFINEON [ Infineon ]
