
TB9100 Reciter Service Manual
Network Circuitry
55
© Tait Electronics Limited January 2006
the 1PPS signal to allow that timer to measure the 1PPS reference’s timing
relative to the internal system time.
Four independent baud-rate generators are provided for use by any of the
internal serial ports. Each of these contains a 12-bit programmable counter
(with optional 16 prescaler) to divide down either the internal CPU clock
or an external clock to a suitable rate for a serial communications interface.
The outputs of the four baud-rate generators can be independently routed
to any combination of the serial controllers.
Interrupt Controller
The interrupt controller in the CPM combines and prioritizes interrupts
from the CPM serial controllers, timers and DMA controller, before feeding
them through to the main interrupt controller in the SIU (see
“Interrupts”
on page 43
).
As well as the internal interrupt sources, the CPM interrupt controller can
accept external interrupts through a number of input lines on parallel port
C. In the ASIF these are used for sensing the power status lines (PWR_ON,
PWD_EX, PWD_RX) from the reciter and the E lead from the E&M
interface (see
“E&M Interface” on page 79
). This frees the software from
having to regularly poll these input lines.
5.2.7
Communications Processor Interfaces
In the ASIF, the serial interface functions provided by the CPM are two
UARTs, an I
2
C port, an SPI port and a TDM PCM port.
The RISC processor in the CPM is supplemented by a serial
communications controller (SCC), two serial management controllers
(SMC), a serial peripheral interface (SPI) and inter-IC (I
2
C) interface
hardware. This hardware performs the lowest level operations such as bit
shifting, clock recovery and FIFO buffering, to reduce the computation
work load on the CPM RISC.
Serial
Communications
Controller (SCC)
Only one SCC, SCC1, is provided in the MPC859T. Consult chapters 21
through 28 of the MPC866 user’s manual (reference 2) for a detailed
description of the capabilities of the SCC.
An SCC can support a multitude of different serial formats, but in the ASIF,
it is only used in UART mode for connection to the reciter internal UART
port. Only the receive data, RISC_RS232_TXD
1
, and transmit data,
RISC_RS232_RXD1
1
, lines are used to connect to the reciter. Although
handshake inputs and outputs are available from SCC1, these are not used in
the ASIF because the reciter does not support them.
÷
1. This signal is named as per the reciter signal naming convention, hence the
apparent contradiction in the signal name vs signal direction.
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