neazoi
Advanced Member level 6
Hi, I have a kind of special requirement. I want two MCUs with serial (TTL) ports to communicate each other over a channel that accepts only audio signals, like the telephone or a ham radio transceiver. Serial speed is at 1200 baud and communication takes place in half duplex only.
Instead of using modem ICs, I was thinking that it may be able to be done much more simply with a few transistors. So I challenge myself in finding ways this can be done, the simplest possible with the fewer components needed. In that sense, I believe ASK will be the simplest way, detect a tone or not, regardless of the frequency, so no filtering is needed.
An idea I had
An AF oscillator on TX, runs continuously and a transistor shunts it's output AF to ground. The transistor being controlled by the TX data. On receive, A detector detects the AF tones (switched on and off) and switches the RX data to 5v or gnd. Since data is half duplex it could work. Some circuicity may be needed to prohibit the RXD during TX and vice versa, so as to not looping back data.
Do you think that would be feasible in a low components count?
Other ways/block diagrams you may think of? (always having simplicity in mind).
Instead of using modem ICs, I was thinking that it may be able to be done much more simply with a few transistors. So I challenge myself in finding ways this can be done, the simplest possible with the fewer components needed. In that sense, I believe ASK will be the simplest way, detect a tone or not, regardless of the frequency, so no filtering is needed.
An idea I had
An AF oscillator on TX, runs continuously and a transistor shunts it's output AF to ground. The transistor being controlled by the TX data. On receive, A detector detects the AF tones (switched on and off) and switches the RX data to 5v or gnd. Since data is half duplex it could work. Some circuicity may be needed to prohibit the RXD during TX and vice versa, so as to not looping back data.
Do you think that would be feasible in a low components count?
Other ways/block diagrams you may think of? (always having simplicity in mind).