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Article #20828Re: Question: 10,000 bit wide UART
From: Henry Spencer
Date: Tue, 21 Feb 1989 17:44
Date: Tue, 21 Feb 1989 17:44
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In article <10108@pasteur.Berkeley.EDU> atn@cory.Berkeley.EDU (Alan Nishioka) writes: > I am trying to build a digital data link, as an experiment, which uses >variable length packets (from 1 to about 10,000 bits in length). > > All of the UART's that I could find only work with up to 9 bit characters. > > Are there any UART's which work with longer bit strings? You don't want a UART at all. The A in UART stands for "asynchronous", which refers to the technique which sends start and stop bits for every character of data to resynchronize receiver and transmitter. If you want to send a whole bunch of bits without start and stop bits, that's *synchronous* transmission, so you want a USRT or USART (which does either). These come in various forms; there are lots of them about. Note that you will need pretty good clock generation, since the receiver clock has to match the transmitter clock to within half a bit time over the time needed to send 10,000 bits. This means either carefully-aligned clocks or some sort of transmission scheme that sends clock information with the data. It may be less trouble to just send 10,000 bits as 1250 8-bit bytes using a UART. Apart from some inefficiency (20% of the bits on the wire are start and stop bits), is there a reason why this isn't adequate? -- The Earth is our mother; | Henry Spencer at U of Toronto Zoology our nine months are up. | uunet!attcan!utzoo!henry henry@zoo.toronto.edu
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Newsgroups: sci.electronics Path: arc1-ca.pugleaf.net!utzoo!henry From: henry@utzoo.uucp (Henry Spencer) Subject: Re: Question: 10,000 bit wide UART Message-ID: <1989Feb21.174450.8770@utzoo.uucp> Organization: U of Toronto Zoology References: <10108@pasteur.Berkeley.EDU> Date: Tue, 21 Feb 89 17:44:50 GMT