[Home]Hand Shakes

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Hand shakes

Running program.

Can send messages to it.

It can poll files.

Have file nanes called start,stop,config.txt

signalling

You have a number of interconnected boxes. They need to signal to each other.

Inside the box logic is kept alive by a clock tick.

The logic can have inputs and outputs.

Outputs can be a voltage or current, or light or tones some other media.

Inputs can convert a voltage or current to a logic or analogue value.

The software needs a logic or analogue value.

Inputs can detect voltage or current or tone.

a simple in band signalling

A telephone circuit is managed.

  phone - circuit - phone

It has a call on it, but what condition is on the circuit outside the call?

How do you signal a start of the call and end of the call.

The circuit is bothway, in that it supports speech in both directions.

Outside the call, a tone is applied.

An old fashioned phone needed a current to power the microphone.

It had a hook switch to hang the receiver on.

A bell was connected when the receiver was on hook.

STATE CONDITION
disconnected noTone
IDLE on hook
Alerting ringing bell
CALL receiver off hook and current flowing
End call receiver on hook and current stops

For a managed telephone circuit.

STATE CONDITION
disconnected noTone
IDLE TONE
CALL noTone
CLEAR TONE


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Last edited May 3, 2022 7:21 am by dougrice.plus.com
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