🚀 go-pugleaf

 KL> Subject: 8-bit Addressable Asynch Receiver/Transmitter? (Like MC14469)
 KL> Organization: Purdue University Engineering Computer Network
 KL> Message-ID: <laird.717688247@stable.ecn.purdue.edu>
 KL> Date: 28 Sep 92 13:50:47 GMT

Hello Kyler!

 KL> I received a pointer to the Motorola MC14469 Addressable Asynchronous
 KL> Receiver/Transmitter in response to a request for info on simple MCU
 KL> network interface chips.  I want something to make residential/
 KL> industrial/automotive control networks "easy" to make.

You know I once wanted to build such a beast. However 'twas going to be with 6803's. Now I realize that such is not a suitable answer to the networking problem, unless 7k/second is okay with you. :-) You could of course rig up a divide by X counter and boost the baud rate of the built in serial port and get a decent speed, however every new message would interrupt the CPU, and then there's bus arbitration and such to contend with.

 KL> The MC14469 is _almost_ ideal - the only problem that I have with it
 KL> is that while it can send back 16 bits of info, it is only able to
 KL> receive 7 bits of data.  I need at least 8 bits.

Hmm, I don't have a listing for that chip. So I'm sortof in the dark as regards it's shortcomings.

 KL> I would appreciate any info on an addressable device that is able to
 KL> receive and transmit 8-bit data.  Simplicity is key.

Simplicity huh?

Well you could take a 6303 (Hitachi's 6803, with a twist), and with some bang-up programming and a touch of analog magic make a two-wire network (gnd + TXRX). Or if you don't mind having a dedicated master, you could skip the electronic magic, and nifty programming and just parrallel the bus thusly:

Master          Slave 1         Slave 2         Slave n
TX -------------+---------------+---------------+----------->
                |               |               |
RX -------------|---+-----------|--+------------|--+--------<
                |   |           |  |            |  |
                RX  TX          RX TX           RX TX

Of course the master's RX line would have to be rigged as follows:

           /----+-----+
RX -------| AND |     \-------< tx from last chip
           \----+---+
                    |                                
                    TX

this would stop you from frying your chips :-)

However most people for networks liek to stay away from standard serial chips. You didn't specify though what speed you'de want. The 6303 (6801 & 6803 too) are well suited to mini-networks because they have provisions for message detection and such.

 KL> Also, are there versions of the M68HC705 that are easy to use for such
 KL> communication?

Bit banger maybe? It's simple from a hardware standpoint.

 KL> Thanks!
Yer welcome, hope it helped.

-Jason

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