Re: TI-H: Serial port


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Re: TI-H: Serial port




Look for "Interfacing the PC" by David Peacock.  Yahoo has it in 5 seconds.
ITs the best source for parallel/interrupt/serial/keyboard hardware info.


>David Knaack wrote:
>>
>> From: Antonio Larrosa <antlarr@arrakis.es>
>> >I'll use (I am using) linux, and already know how to send bytes through
>> >the port, but I've read the communication goes bit per bit.
>> >
>> >Now, how can I handle directly what is being send through each pin in
>> >the serial port ?
>> >Anybody knows where can I find such information ?
>>
>> The data is sent using the signaling wires (CTS, DTR, etc), you just
>> set and read states like that, you never actually send bytes over the
>> serial wires.
>>
>
>Thanks for the info, now I understand how can I use a serial port to send
>bit per bit instead of a whole byte at a time.
>Sorry for not answering before, I've been busy searching and reading info
>about the serial port (in some books and Ralf Brown interrupt/port/whatever
>hardwareyouhave lists )
>
>Now, I have this list of ports, could you please tell me which one has
>the status I have to read and write ?
>
>02F8    w       transmitter holding register
>02F8    r       receiver buffer register
>        r/w     divisor latch, low byte   when DLAB=1
>02F9    r/w     divisor latch, high byte  when DLAB=1
>        r/w     interrupt enable register when DLAB=0
>02FA    r       interrupt identification register
>02FB    r/w     line control register
>02FC    r/w     modem control register
>02FD    r       line status register
>02FF    r/w     scratch register
>
>I supposed it's 0x2FD, but it's only read, so in case it is, I should
>read from one and write to another port, isn't it ? Also, I've been
>thinking, to use the serial port reading and writing status, I should
>set the pins 3,4 and 7 to a given voltage so that pins 6 and 8 transmit
>the same values as the calculator ends, isn't it ?
>
>Also, I've tried to make an app that makes a loop reading every port
>(not every port of course :-) just those 8 ones), while I used the calc
>to "Send Product Code" and send a variable (in the Var-Link menu), but
>this application always read the same values.
>
>I know there must be a "communication" to transmit a bit, but at least,
>if the calculator starts sending something, at least a bit should change
>in one of the ports, but it doesn't.
>
>> I haven't the slightest clue how you would do that in Linux, but I'd guess
>> its fairly straightforward.
>>
>
>The communication with the ports is the same as in dos, I just need to be
>root to send and receive data through a port (that is, to use the asm "in"
>and "out" opcodes), but for now, I can live running this app setuid.
>Anyway, I wasn't asking for already done sources, but for help on how
>to use the serial port (btw, is there any application available which
>releases its source code ? :-) )
>
>Greetings,
>
>--
>Antonio Larrosa Jimenez
>Student of Mathematics
>antlarr@arrakis.es        larrosa@kde.org
>http://www.arrakis.es/~rlarrosa
>Klein bottles for rent -- inquire within.



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