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From: nahshon@dan.haifa.ibm.com (Itai Nahshon)
Subject: Re: Proposed 68HC11 board
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Message-ID: <NAHSHON.94Aug15145138@dan.haifa.ibm.com>
In-Reply-To: farnham@lmsc.lockheed.com's message of Sun, 14 Aug 1994 22:31:37 GMT
Date: Mon, 15 Aug 1994 11:51:38 GMT
Disclaimer: This posting represents the poster's views, not necessarily those of IBM.
References: <farnham-140894152859@129.197.52.35>
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In article <farnham-140894152859@129.197.52.35> farnham@lmsc.lockheed.com (Greg Farnham) writes:

>Take the miniboard 2.0, add 32K battery backed up ram, and a high current
>(1-3amps) dual motor driver.   Maybe a few connectors for servos.  Make it

By adding a 1 of 10 counter/decoder (4017 cmos chip?) and hooking it to two
timer port one can control up to 9 servos independently. The HC11 can be directly
connected to up to 4 of these chips and have 36 servos under it's control!
Pulse reset 50 times a second. Follow reset by 9 clock pulses which are timed
for the wanted positions of the 9 servos.
Servos are hooked to outputs 0-8 of the counter (do NOT use the last output!).
Similarly a 1 of 8 counter can be used to control up to 7 servos.
An 8 bit serial-in-parallel-out shift register can be used to control 8 servos.

I believe 36 servos is too many for most miniboard users, but the addition of a
single 16 pin chip hooked to two timer output pins can be justified.

Itai Nahshon
Haifa, Israel
email: nahshon@vnet.ibm.com


