technical manual for sailor compact hf ssb t2130 - Gopher Proxy
technical manual for sailor compact hf ssb t2130 - Gopher Proxy
technical manual for sailor compact hf ssb t2130 - Gopher Proxy
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5 CIRCUIT DESCRIPTION AND SCHEMATIC DIAGRAMS T2130<br />
As the level on the SP-Bus approximately matches the RS232C standard, it is possible to connect an<br />
RS232C to the SP-Bus. The cable terminations (jumper P04) must be removed when the external<br />
RD232C is to transmit on the SP-Bus.<br />
SERIAL DEVICE BUS DRIVER & SELECTOR<br />
The serial device bus consists of:<br />
- clock<br />
- Data Out<br />
- Data In<br />
- several select lines<br />
- special select <strong>for</strong> the A/D converter<br />
The serial bus occupies 6 bits of port 6 on the microprocessor. Bit 0, bit 1, and bit 2 are connected to the<br />
serial device selector, bit 3 is the special select <strong>for</strong> the A/D converter, bit 6 is the clock, and bit 7 is data.<br />
The serial device selector is a 3 to 8 line decoder 74HC237 (U07). The 3 input lines give 8 selects on the<br />
output, one selected at a time. The following codes are used:<br />
0 - none is selected<br />
1 - EEPROM U11<br />
2 - EEPROM U12<br />
3 - shift register U10, filter module driver<br />
4 - shift register U14, tune motor control<br />
5 - AT2110 driver<br />
6 - not used<br />
7 - A/D converter, reference voltage switch<br />
The serial device selector is supplied by +5VB.<br />
The serial device bus driver consists of 3 lines:<br />
- clock, port 6, bit 6<br />
- Data Out, port 6, bit 7<br />
- Data In<br />
In order to have a safe communication, the clock and Data Out are buffered. The buffers are 74HC08<br />
(U08/3 and U08/4) supplied by +5VB.<br />
The Data In line is connected direct to Port 6, bit 7. R04 ensures a definite impedance on the Data In line.<br />
To inhibit an unknown current sink in the serial device bus when the supply is failing, the buffers are gated<br />
with PFO signal from the battery low detector (U03, pin 5).<br />
EEPROMS<br />
U11 and U12 EEPROMS are supplied by the back-up voltage +5VB. They are connected to the serial<br />
device bus direct to the microprocessor as the serial device bus closes down when the +18V is failing.<br />
U11 and U12 EEPROMS remember the data <strong>for</strong> the fast retune of the AT2110.<br />
By use of service programmes it is possible to delete these retune data.<br />
PAGE 5-12<br />
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