DACS App Note

Watchdog Timers for Model Builder (#12)

Model Builder supports several types of Watchdog Timer signals via the parallel port. The table below lists the corresponding parallel port bit number, the watchdog timer signal description, and the Model Builder version where the signal was first implemented.

Care should be taken when interfacing to the DACS parallel port as improper interface could cause parallel poert of possibly CPU failure.

Active
Pin Bit Function Toggle High MB Version
2 0 Model Builder (MB) Running X 3.03+
3 1 Model Builder running w/ no errors X
4 2 Model Builder running w/ no errors X 3.03+
5 3 MB running; DSPs running OK X 3.03+
6 4 DSPs not muted X 3.04+
7 5 MB running; main Rx packet from host active X 3.03+
8 6 No system errors X 3.04+

25-Pin PC-Compatible Parallel Port Connector


Pin Description I/O
1 -Strobe Out
2 +Data Bit 0 Out
3 +Data Bit 1 Out
4 +Data Bit 2 Out
5 +Data Bit 3 Out
6 +Data Bit 4 Out
7 +Data Bit 5 Out
8 +Data Bit 6 Out
9 +Data Bit 7 Out
10 -Acknowledge Out
11 +Busy In
12 +Paper End In
13 +Select In
14 -Auto Feed Out
15 -Error In
16 -Initialize Printer Out
17 -Select Input Out
18 -Data Bit 0 Return (GND) In
19 -Data Bit 1 Return (GND) In
20 -Data Bit 2 Return (GND) In
21 -Data Bit 3 Return (GND) In
22 -Data Bit 4 Return (GND) In
23 -Data Bit 5 Return (GND) In
24 -Data Bit 6 Return (GND) In
25 -Data Bit 7 Return (GND) In