MSX-E1701: Digital I/O
Functions of the module
short-circuit. Every further write access to this port is ignored.
5.
The output port firstly does its old function as soon as the short-circuit is
removed and a rearm (diagnostics control register) is realized.
The digital inputs are not concerned by this function.
8.4
Watchdog
The Ethernet I/O module
MSX-E1701
has a 16-bit watchdog that can be
programmed in three time bases (
μ
s, ms, s). The watchdog is for resetting the
digital outputs on 0 V after a certain time (Reload Value).
Function
:
1.
Firstly the watchdog is activated.
2.
The watchdog-counter is started with the „Reload-Value“ at each write
access to the outputs.
At each write access to the outputs it is counted down newly with
the
„reload
value“.
3.
If there is a watchdog underrun:
- all digital outputs are set on 0 V
- an interrupt is generated
- the underrun bit is set (the enable bit remains set)
4.
As long as the watchdog is in the „underrun“, each write access to the
outputs is ignored.
5.
In order to delete the „underrun bit“ and to enable the write access again,
the watchdog must be disabled (Enable=0).
6.
In order to reactivate the watchdog, the enable bit must be set again on 1.
10
See also software functions and samples for the „Watchdog“ chapter
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