Tait TB8100 Service Manual page 34

Responsibilities
34 Reciter Circuit Description
The RISC communicates with the DSP's shared memory via a host port
interface. It loads the DSP code and monitors and controls the following
DSP operations:
receive path
transmit path
crosspoint switches
power supplies
PA Key output.
The RISC controls the frequency generation subsystem. It detects an
external reference source and selects internal or external reference. It also
programs, and handles out-of-lock signals for, the following synthesizers:
12.8MHz external reference synthesizer
40MHz digital clock synthesizer
receiver synthesizer
exciter synthesizer.
The RISC communicates with the control panel via I
read the button states
read the microphone PTT state
control the LEDs
turn the speaker amplifier on and off
turn the microphone amplifier on and off.
The following signals go via the control panel for signal conditioning:
Service Kit communication via the RS-232 interface
fan-good indication (front panel fans).
Note that the volume control on the control panel is analogue only and is
not controlled by the RISC.
The RISC communicates with the other modules in the subrack via I
order to:
verify that they are present
write configuration settings
read their current status.
The RISC subsystem communicates with the system interface board via SPI
to:
set input and output gains
mute and unmute outputs
read digital inputs
write digital outputs.
2
C bus to:
TB8100 Service Manual
© Tait Electronics Limited September 2006
2
C in