User guide

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62
Pin Function In/Out
1 VCC +5V -
2 ANIN (analogue multiplex input) I
3 Not Used (connect to GND) I
4 Not Used (connect to GND) I
5 Not Used (connect to GND) I
6 Not Used (connect to GND) I
7 Not Used (connect to GND) I
8 BCD Hundred 1 I
9 BCD Hundred 2 I
10 BCD Hundred 4 I
11 VCC 5V -
12 GND -
13 Osc1 (16MHz crystal) -
14 Osc2 (16MHz crystal) -
15 Good Rx (Open Collector, Lo=Good) O
16 NC -
17 Scope Trigger O
18 NC -
19 A0 O
20 A1 O
21 A2 O
22 CS Address 0 O
23 NC -
24 NC O
25 DMX512 TTL Transmit O
26 DMX512 TTL Receive I
27 CS Address 1 O
28 CS Address 2 O
29 CS Enable O
30 Chip Select 8 O
31 GND -
32 VCC (5V) -
33 BCD Unit 1 I
34 BCD Unit 2 I
35 BCD Unit 4 I
36 BCD Unit 8 (msb) I
37 BCD Ten 1 I
38 BCD Ten 2 I
39 BCD Ten 4 I
40 BCD Ten 8 (msb) I
Pin
Functions
Circuit
Operation
The AL4020 and 74LS138 provide chip selects and address
outputs which are used to address a single analogue input from
the 72 available.
The level is converted to an 8 bit digital value and buffered
internally.
The level buffer is passed through a digital filter to reduce
analogue noise and bit jitter prior to forming the final output.