Problems w/ Serial Comm Example

LiftMaster

I am trying to make the example code in Chapter 4 of the Javelin manual, HyperTermCOM) work, without success. I am using the Basic Stamp Super Carrier board (as opposed to the Javelin Stamp Carrier board).

I can successfully compile & download the sample program to the Javelin. ( BTW - I have successfully run other programs on the Javelin)

I am connecting to the Javelin thru the serial port of my laptop. I am using the pins specified in the sample program (namely P0 thru P3) and have verfied that the wiring is correct. I download the program to the Javelin, shutdown the IDE, reconnect the serial cable from the programming port to the communication port that I have wired to pins p0-p3 and start HyperTerminal with the appropriate comm settings the press the reset button on the Javelin. I get nothing displayed in HyperTerminal.

Do I need to use a RS232 transceiver to convert the Javelin logic levels to +12 & -12 volts for the serial port on the laptop?

If so, then how does the programming port on the Javelin work?

Any help is appreciated,

Thanks...

Peter Verkaik

Yes, you do.

The Javelin program port works as the Basic Stamp programming port.

It steals the RX rest level (-12V)·to use that for transmitting

(so transmit levels are -12V and +5V).

Normal I/O pins only have 0V and +5V.

regards peter