Technical description
4-22 HF SSB Transceiver 9323/9360/9390/9780 Technical Service Manual
I
2
C buses
There are three I
2
C bus lines:
• EXT I
2
C bus—This provides two-way serial data communication between the
microprocessor IC2 pins 22 and 23 in the control head [1 04-02974] and the
microprocessor IC101 pins 22 and 23 on the Microprocessor and Audio PCB
[1 04-02976 Sheet 1]. The data line, SDL, conveys information and the
transfer is synchronised by transitions on the clock line, SCL.
• Local I
2
C bus—(shared with the PA Serial Bus) allows the microprocessor
IC101 pins 7 and 8 to communicate to:
IC108 E
2
PROM—16 kbit memory device used to contain general function
commands such as Selcall Ident, tone frequencies, etc.
IC109 and IC114—two 16–bit output ports that have different addresses set by
pin 1. Serial data is read by both ICs but only the one that matches the address
portion of the data stream will latch the selected IC's 16–bit parallel output. The
two ICs provide a total of 32 open drain outputs to various control circuits
throughout the transceiver.
IC209 and IC111—two 8–bit In/Out integrated circuits. IC111 [1 04-02976
Sheet 1] and IC209 [1 04-02972 and 04-03135 Sheet 2] convert their eight
ports to serial data for application to the bus. They convert serial data from the
bus to parallel at their ports. They have different addresses and are set by the
address pins 1, 2 and 3.
When a data transfer is required, the microprocessor IC101 outputs the address
of the required IC on the data line, followed by a Read/Write command. Data is
read from, or written to, the selected IC. When a change at the input ports
occur, the IC with the change sends an interrupt to the microprocessor IC101
pin 27. The microprocessor interrogates each IC in turn until the changed data
is read. The selected IC removes the interrupt and the microprocessor is then
able to continue with other operations.
IC2—8–bit output port located on the Rx/Exciter PCB[1 04-02972 Sheet 1].
This IC selects the appropriate HPF, and when required, the RF filter.
IC110—The real time clock.
• Synthesiser I
2
C bus—(shared with the synthesiser bus)
IC112—[1 04-02976] battery backup RAM stores the latest operator
commands such as current selected channel, volume level, mute on/off, selcall
information etc. It retains this information when the transceiver is switched off.
When powered up again, the microprocessor reads the information stored in
IC112 and resets the transceiver to the last settings before it was switched off.
IC210—E
2
PROM is a 2 kbit memory device located on the Rx/Exciter PCB
[1 04-02972 and 04-03135 Sheet 2] and is not used at present. It will be
available for future applications.
To Next Page
Loading...
Need help?
General
