Specifications

VSBC-6862 Rev 1.43

2.11. SCC multi-protocols serial ports

The VSBC-6862 offers four independent serial ports.

In synchronous mode, all four ports have independents RX clock signals, but only SCC1 and SCC2

have TX Clocks signals.

These ports are directly controlled by the Serial Communication Controllers (SCC) included in the

PowerQUICC II. These SCC includes functions like support of many protocols like UART and HDLC, it

contains also FIFO buffers: 32 byte deep, and many more powerful options.

All the four ports are available on four Sub-D-HD-15 connectors on front panel.

The interface level of these ports can be RS-232/RS-422/RS-485 or V.35.

Switching between these options can be done through the 'serial mode' jumpers.

The serial ports 1 and 2 have an added function: they can be internally used to synchronize the

internal Baud Rate Generators (BRG) with external clock signals.

Note that due to pin multiplexing in the PowerQUICC II, the Transmit Clock for the serial port 4 can't

be used in same time with the IP slot B DMA channel. The user must use either DMA on IP B, either

Transmit Clock on serial port 4.

RS-232 mode

These VSBC-6862 ports are in a standard RS-232 mode.

The following signals are controlled by the PowerQUICC II:

TxD, RxD, TxC, RxC, CTS, RTS, and DCD

All ports support hardware handshaking and synchronous functions.

DSR signals are pulled-up to VCC to indicate that the board is powered-up.

RS-422/RS-485/V.35 modes

These VSBC-6862 ports are compatible with these three modes.

The following signals are controlled by the PowerQUICC II:

TxD, RxD, TxC, RxC in differential mode for RS-422, RS-485 and V.35

CTS, RTS and DCD in RS-232 mode for V.35

Note: As described above, the VSBC-6862 did not provides all defined signals for V.35, it provides

all 'transmission signals' but not for example, the loopback or ring indicator signals.

All ports support full and half-duplex mode, and supports also synchronous operations.

The internal I/O ports dedicated to RTS is connected to the internal data transmit enable signal.

This permits to determine the function for half or full-duplex modes as:

Full-duplex: configure RTS always active

Half-duplex: configure RTS as normal RTS

The PowerQUICC II has also the possibility to disable his receiver while emitting (see bit DRT in

Each port has its own network resistors.

These resistors are on sockets. ACTIS choose to implement manual network resistors to keep the RS-

485 network always working, independently of the power state of the VSBC-6862.

These resistors network are to be installed only when the corresponding serial port is at one of both

ends of the RS-485 network cable.

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