Re: TI-H: Re: Ir Link compatability
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Re: TI-H: Re: Ir Link compatability
Matthew H. Fogle wrote:
> I don't know much about how this works and how he designed it; but I'm
> going to go out on a limb and guess that this works by using the RS232
> driver much as a computer would. It takes the reverse logic from the TI;
> makes it normal logic with the inverters. Then makes a RS232 port the
> same way a computer does by having that chip connect to CPU IO lines.
> The IR chips maybe multiplex the signals from the lines then. I haven't
> read the data sheets so I don't know if this is likely but it sounds
> like how it would have to work. Can someone else build it and verify
> it's working? I will as soon as I recieve the chips.
According to the datasheets, the IR transmitter module is quite simple:
When it gets a 1 (high) state on its input pin, it sends a 500 kHz IR
signal, and when the state is 0, it doesn't send anything. Accordingly, the
receiver module makes its output 1 when it "sees" a 500 kHz IR signal and 0
if it doesn't see any signal. There is no multiplexing in the IR modules,
and no multiplexing in the other parts of the circuit, so the IR data
channel is effectively limited to one bit, half duplex (full duplex can be
achieved in optimum conditions according to the datasheets). Two bits half
duplex would be the minimum required for the TI protocol.
Your computer analogy does not work, because a computer has an UART in
between the CPU and the RS232 port. This IR link hasn't got one.
-Ozone
--
*** Osma Suominen *** ozone@clinet.fi *** http://www.clinet.fi/~ozone ***
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