BCM1250/BCM1125/BCM1125H
User Manual
10/21/02
B r o a d c o m C o r p o r a t i o n
Page
338
Section 10: Serial Interfaces
Document
1250_1125-UM100CB-R
L
INE
I
NTERFACE
The Line Interface controls the flow of bits between the protocol engine and the external pins. In the receive
direction it assembles a bit stream and clock for the protocol engine. In the transmit direction it fetches bits from
the protocol engine and formats them for the line.
The serial channels share pins with the DUARTs. Each port can independently be configured for synchronous
serial operation or for UART operation using reset time configuration resistors or by software (see
). When port 0 is configured for synchronous mode, it is connected to channel 0;
similarly, port 1 to channel 1.
The 8 pins for each interface are used as follows in synchronous mode.
In addition, the following GPIO pins can be driven from the serial port when the appropriate reset time
configuration resistors select this use (see
Table 223: Synchronous Serial Interface Signal Names
Pin
Direction
Synchronous serial port Function
DOUT
Output
Transmit data output
CTS_TCLKIN
Input
Transmit clock input
TIN
Input
Transmit enable or frame synch input
RTS_TSTROBE
Output
Transmit strobe output
DIN
Input
Receive data input
CIN_RCLKIN
Input
Receive clock input
RIN
Input
Receive enable or frame synch input
COUT
Output
Baud rate generator output
Note that the configuration must be set in the UART control block, in order for the baud
clock to be output on this pin.
Table 224: Synchronous Serial Interface GPIO Pins
Pin
Direction
Channel 0
Channel 1
Function
RSTROBE
Output
GPIO[0]
GPIO[1]
Receive Strobe Out