Gymna Pulson 330, Руководство по обслуживанию

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11. Keyboard.
The keyboard consists of only 7 keys, which therefore can be directly
coupled to the
µ
p.
C8 filters out all HF-noise, and all diodes prevent keyboard
discharges from entering the processor inputs.
The keyboard is connected to CON4.
Another feature of this circuit is the ability to detect the hardware
version from the apparatus.
There are two possibilities: either the hardware version ( defined by
jumpers on JP1) or the keyboard information is read. The selection is
made by the KEY_SELECT pin.
In case of a high level signal, Q1 opens and the
µ
p reads the keyboard
status. If KEY_SELECT is low, hardware version jumpers are read into
the
µ
p.
When starting up, the
µ
p first reads the hardware version, and then
checks if the present software version corresponds. If not, an error
code is produced.
Hardware and software version may simply be checked by holding a key
when starting up.
Both will be displayed for about 10 seconds, after which the unit
returns to standby.
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