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0855B–HIREL–04/08
TS68302
e2v semiconductors SAS 2008
9.8 Communications Processor
The CP in the TS68302 includes the main controller, six serial DMA channels, three SCCs, an SCP, and
two SMCs.
Host software configures each communications channel, as required by the application, to include
parameters, baud rates, physical channel interfaces desired, and interrupting conditions. Buffer struc-
tures are set up for receive and transmit channels. Up to eight frames may be received or transmitted
without host software involvement. Selection of the interrupt interface is also set by register bits in regis-
ter space of the device.
Data is transmitted and received using the appropriate buffer descriptors and buffer data space for a
channel. The CP operates is a modified polling mode on each channel and buffer descriptor to identify
buffers awaiting transmission and channels requiring servicing. The user sets a bit in the buffer descrip-
tor of a transmit frame; when the CP polls and detects this bit, it will begin transmission. Generally, no
other action is required to accomplish transmission.
9.8.1 Main Controller
The main controller is a microcode RISC processor that services all the serial channels. The main con-
troller transfers data between the serial channels and internal/external RAM, executes host commands,
and generates interrupts to the interrupt controller.
Data is transferred from the serial channel to the dual-port RAM or to the external memory through the
peripheral bus. If data is transferred between the SCC channels and external memory, the main control-
ler uses up to six serial DMA channels for the transfer. The main controller also controls all character and
address comparison and cyclic redundancy check (CRD) generation and checking.
The execution unit includes the arithmetic logic unit (ALU), which performs arithmetic and logic opera-
tions on the registers.
9.8.2 Serial Communication Controllers
The TS68302 has three independent SCCs. Each SCC can be configured to implement different proto-
cols - for example, to perform a gateway function or to interface to an ISDN basic rate channel. To
simplify programming, each protocol implementation uses identical data structures.
Five protocols are supported: high-level data link control (HDLC), binary synchronous communication
(BISYNC), synchronous/asynchronous digital data communications message protocol (DDCMP), V.110,
universal asynchronous receiver transmitter (UART), and a fully transparent mode. To aid system diag-
nostics, each SCC may be configured to operate in either an echo or loopback mode. In echo mode, the
IMP retransmits any signals received; in loopback mode, the IMP locally receives signals originating
from itself.
The clock pins (RCLK, TCLK) for each SCC can be programmed for either an external or internal source,
with user-programmable baud rates available for each SCC channel.
Each SCC also supports the standard modem control signals: request to send (RTS), clear to send
(CTS), and carrier detect (CD). Other modem signals may be provided through the parallel I/O pins.
The SCC features are as follows:
• programmable baud rate generator driven by the internal or external clock,
• data may be clocked by the programmable baud rate generator or directly by an external clock,
• provides modem signals RTS, CTS, and CD,
• Full-duplex operation,