Hi all,
I'm working on a senior design project for school which involves the
wireless communication of 2 palm devices. I'm using the UART of the palm to
handle the communications. They lines are fed through a MAX232 transceiver
and then to the wireless hardware (a transmitter and receiver).
Everything works fine, except the MAX232 inverts the signal such that
0's are high and 1's are low (only way for the receiver to know what really
is a 0 or a 1, since rs232 has +Vcc for high and -Vcc for low).
My problem is that the transmitter is now always on, even when I'm not
actually sending data. I need another control line to actually turn the
transmitter on during a transmission and off otherwise.
Since I have the baud set to 1200, I don't need to use hardware flow
control, so I'm looking to use RTS as a control line. I've been trying to
find code (either using the API or with assembly) to actually do this, but
I've been unsuccessful thus far.
I can guarantee that the hardware and software will only be used with
m100 palms, so compatibility with later devices isn't an issue (using
assembly to directly manipulate the RTS or DTR line for the m100
specifically would work in my case).
I have also tried to use the built in API function SrmControl with the
"srmCtlSetDTRAsserted" opcode. I'm passing it a boolean variable set to
"false" after I open the serial port with "SrmOpen". Unfortunately when
probing the DTR line I still get +6V, expecting ~+3V when the line is off
(not asserted). If anyone has tried to manually assert the DTR line low or
high before, please let me know - since I need +5V to operate the wireless
transmitter, I can use the DTR line to effectively turn the wireless
transmitter on and off also.
Once again, this is for a senior design project, it's our only hold up
and we have a couple weeks left. Any suggestions, links to reference
documentation for the m100 hardware or more info about the palmOS 3.5 api
would be a great help. If anyone has source code related to controlling the
DTR or RTS line manually that would be awesome.
Thanks for taking the time to read this,
Morgan J. Demers
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