[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Rander box

>   It will have two serial connectors,   one an input,  and other the
>output,   and connect to a modem or serial port.   Physically,  it should
>have dip switch to select baud rate,   and an on-off switch.

Some simplifications I might suggest:

I only think you need an output connector.  See below.

If you can power it off the RS-232 line, you won't need a power
switch.  You should be able to draw enough power off, say, the DTR
line to power a simple thing like this.

For a dedicated random number generator with low bandwidth, there's
not much reason for variable baud rate.  I'd use a fixed baud rate of,
say 1200, or even 300.  If you make it low enough you could just
kludge together a serial interface, but with the low cost of UART's,
it's probably not worth it.  You might also consider using a PIC, which
has built-in serial.

>   When switched on,   and a "cr" (or some other character) is sent to it,
>random bytes will stream out continiously.   

I'd just make the thing spew continuously.  It's not like you're
losing real, er, information if you ignore a few random bits.  This
way you don't need the added circuitry for switching on and off.

The actual use of this thing is going to require a device driver to
buffer up random bits for later use.  So all the flow control to the
higher layer happens there anyway.  And if the UART buffer overflows,
so what?