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Subject: 
Re: 6 servos
Newsgroups: 
lugnet.robotics.handyboard
Date: 
Wed, 22 May 1996 16:17:58 GMT
Original-From: 
MAR ERICSON <mar@cooper.STOPSPAMMERSedu>
Viewed: 
1077 times
  

The boards take serial input (2400 or 9600 baud).  It is
straightforward to write a 6811 assembly routine to output such serial
signals on an arbitrary digital output.

Are the digital outputs at 5v high? I think you mentioned on the HB
homepage about the serial interface converting RS232 levels at +12 and
-12v to TTL level s (5v). I'm not that familiar with the nitty gritty
of RS232 so this kinda puzz les me.

There are two types of serial voltages: TTL level and RS-232 level.
The HB's serial interface board converts from TTL to RS-232 for
communicating with the host computer.

The Scott Edwards board accepts TTL levels, so an HB pin can drive it
directly.

The translation between logical level (e.g., is the bit a 1 or a 0),
TTL, and RS-232 is anything but obvious:

logical level TTL level RS-232 level

zero or idle     +5v -12v
one   0v +12v


Just to make sure it wasn't a typo...so, the TTL level is "ative low"?

Also. Does the Scott Edwards board have the ability to be connected to a computer? or do you need a "TTL to RS232 converter"?



Message is in Reply To:
  Re: 6 servos
 
(...) There are two types of serial voltages: TTL level and RS-232 level. The HB's serial interface board converts from TTL to RS-232 for communicating with the host computer. The Scott Edwards board accepts TTL levels, so an HB pin can drive it (...) (29 years ago, 22-May-96, to lugnet.robotics.handyboard)

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