[Tinyos-help] about connecting gprs modem using uart

[Jordi Llosa]

Hi there!

I want to communicate the telosb with a gprs modem (siemens TC65) using a
serial port, the idea is use the serial port to send and receive (using
SerialAMReceiverC and SerialAMSenderC) data, and configure the modem to send
the data to a remote pc.

As Bill, in other email, pointed out, there are some issues.

The first one is the voltage levels, I read that could be solved by using
the max3232 to convert from 3V to 5V, to have a true rs232 connector.

The second one, and here comes my headache is wich of the uart port should I
use. There are 2 options:
1- use the uart0 rx and tx from the expansion ports. But I will need to
listen the CC2420 all the time, so here is the problem. (I'm not sure of it
because I checked the tmote datasheet and I haven't seen any of the pins
shared by the uart0 and CC2420, is it internal from the msp430?). In
tinyos-2 there are some resource managers, does anybody knows if the
problems could be solved with it?

2- use the uart1, for me this would be perfect, because I'm already sending
the data over this port, but to take the serial I do have to do some
hardware changes to the tmote. What do you suggest? getting out the usb chip
and connecting the max3232 there? I thing this is a bit dangerous, and there
is high probability to crash the tmote. Or maybe there is a possibility to
reconvert from the usb to serial another time using another chip?

Excuse for my novice.

Jordi
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