3-20
3.1.4.8 Port Expander
U703 is a port expander that is controlled by the auxiliary SPI of the Trident IC; pins A7
(ASPI_DATA), B7 (ASPI_CLK) and C6 (ACE1_GPO7). Data sent on the main SPI bus with a specific
header, tells the Trident IC to pass the data (via the auxiliary SPI lines) onto the port expander SPI
lines, pins 32 (SCLK), 33 (DIN) and 34 (CS). The port expander then translates this auxiliary SPI
data and turns on and off the select lines for the various VCOs, switches (that select the correct RF
path for either VHF, UHF Range 1 or 7/800) and other logic external to the FGU.
shows the logic settings for the port expander for the various bands.
VHF TX
VHF RX
700 TX
700 RX
7/800 TX
800 TX
800 RX
Table 3-3. Port Expander Pin Settings
PIN NO.
1
2
3
LOGIC
0
0
0
PIN NO.
16
17
18
LOGIC
0
H
0
PIN NO.
1
2
3
LOGIC
H
H
H
PIN NO.
16
17
18
LOGIC
0
0
0
PIN NO.
1
2
3
LOGIC
0
0
0
PIN NO.
16
17
18
LOGIC
0
0
0
PIN NO.
1
2
3
LOGIC
0
0
H
PIN NO.
16
17
18
LOGIC
0
0
0
PIN NO.
1
2
3
LOGIC
H
0
0
PIN NO.
16
17
18
LOGIC
0
0
0
PIN NO.
1
2
3
LOGIC
0
0
0
PIN NO.
16
17
18
LOGIC
0
0
0
PIN NO.
1
2
3
LOGIC
0
0
H
PIN NO.
16
17
18
LOGIC
0
0
0
4
5
6
7
8
0
0
0
H
H
19
21
22
23
24
0
0
H
H
H
4
5
6
7
8
H
0
0
0
0
19
21
22
23
24
0
0
H
0
0
4
5
6
7
8
0
H
0
0
0
19
21
22
23
24
0
0
H
0
0
4
5
6
7
8
0
H
0
0
0
19
21
22
23
24
0
0
H
0
0
4
5
6
7
8
0
0
H
0
0
19
21
22
23
24
0
0
H
0
0
4
5
6
7
8
0
H
0
0
0
19
21
22
23
24
0
0
H
0
0
4
5
6
7
8
0
H
0
0
0
19
21
22
23
24
0
0
H
0
0
Theory of Operation: Transceiver Board
Table 3-3
9
10
12
13
0
0
0
0
25
26
27
28
0
H
0
0
9
10
12
13
0
0
0
0
25
26
27
28
0
0
0
0
9
10
12
13
H
0
0
0
25
26
27
28
0
0
H
H
9
10
12
13
0
H
0
0
25
26
27
28
0
0
0
0
9
10
12
13
0
0
0
0
25
26
27
28
0
0
H
H
9
10
12
13
0
H
0
0
25
26
27
28
0
0
H
H
9
10
12
13
H
0
0
0
25
26
27
28
H
0
0
0
below
14
15
0
0
29
30
0
0
14
15
0
0
29
30
0
0
14
15
0
0
29
30
0
0
14
15
0
0
29
30
0
H
14
15
0
0
29
30
0
0
14
15
0
0
29
30
0
0
14
15
0
0
29
30
0
H