The Tx and Rx in a RS-232 do indeed act much like I/O for a UART, but they
are generally speaking the opposite (at least from my other
experience)....ie. the generic UART defaults low, asserts high, the RS-232
defaults high, asserts low.....essentially my output is the exact opposite
of what i need/expected from an RS-232, the start bit goes high, instead of
low, and the 0's are high while the 1's are low....i'm considering just
throwing an inverter in between, but that could get a little messy for now...
thanks,
ben
At 10:05 AM 7/25/2000 -0700, you wrote:
>The TX and RX of RS-232 is essentially UART output (UART -> Voltage
>Converter -> connector, matches standard). Also, remember that RS-232 uses
>+/- 12V (nominal) levels, so you will need conditioning before connecting to
>a PIC.
>
>Good Luck,
>-jjf
>
>-----Original Message-----
>From: Ben Hamby [mailto:[EMAIL PROTECTED]]
>Sent: Tuesday, July 25, 2000 9:36 AM
>To: Palm Developer Forum
>Subject: RE: Serial Communications
>
>
>I see what you mean now, as far as the differences between the SPI and the
>common UART(ie. 16550)...However, isn't the RS232 supposed to have similar
>output to the SPI? Ie. defaults high, assertions are low....and I thought
>the Palm had an RS232...does it have both and defaults to using the 16550
>protocol? Or am I out in right field without a glove....
>
>Thanks,
>Ben
>
>At 03:14 PM 7/24/2000 -0700, you wrote:
> >The SPI is quite a bit different from a standard async serial port. You
>can
> >implement an async serial port in software on most PICs. I did one a long
> >time ago on a PIC16C50 derivative and it worked pretty well.
> >
> >If you go to www.microchip.com and select Application Notes, a note on
> >implementing an async port will be one of the first ones listed.
> >
> >Good Luck,
> >-jjf
> >
> >-----Original Message-----
> >From: Ben Hamby [mailto:[EMAIL PROTECTED]]
> >Sent: Monday, July 24, 2000 12:43 PM
> >To: Palm Developer Forum
> >Subject: Serial Communications
> >
> >
> >Hello,
> >
> >I'm doing serial communication between my Palm and another device that uses
> >a PIC processor. Just had a few questions I was wondering if anyone could
> >answer about the format of the output more than how to program it. (all of
> >this is from the Tx line) Right now, I just send some information out of
> >the SerSend command and it sends fine, but I was wondering if the Palm by
> >default includes a 1 bit start bit. Currently, it seems like the line
> >defaults to Low(0) and then sends a 1 bit High(1) out of the Tx before it
> >sends a byte. Is this how normal serial communication is performed? I
> >thought the serial communication went in a similar style to the SPI, where
> >it defaults to a High and then sends a 1 bit Low before sending the
> >information? Is my information incorrect? If it is, and that is how normal
> >serial communication is performed, does anyone have any suggestions to get
> >it to work with the SPI?
> >
> >Thanks,
> >Ben
> >
> >
> >--
> >For information on using the Palm Developer Forums, or to unsubscribe,
> >please see http://www.palmos.com/dev/tech/support/forums/
> >
> >--
> >For information on using the Palm Developer Forums, or to unsubscribe,
> >please see http://www.palmos.com/dev/tech/support/forums/
>
>
>--
>For information on using the Palm Developer Forums, or to unsubscribe,
>please see http://www.palmos.com/dev/tech/support/forums/
>
>--
>For information on using the Palm Developer Forums, or to unsubscribe,
>please see http://www.palmos.com/dev/tech/support/forums/
--
For information on using the Palm Developer Forums, or to unsubscribe, please see
http://www.palmos.com/dev/tech/support/forums/
