BS2sx progaming serial port stop working while GPS is connected

Toide

I’m having some terrible issues connecting a Garmin eTrex GPS to my Stamp Module. ·I’m connecting the GPS just using pin 2, TDX and Ground, initially I interface with a Pharos 360 GPS without problems but when I connect the Garmin unit the programming port just die, The PC is unable to recognize the Stamp until I disconnect the GPS unit, then I can transfer data again from the PC to the Stamp. ·I try connecting the unit to pin 3 and 13 with the same results. There is something an I doing wrong?
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My stamp is using a 8 VDC connected to Vin and Vss, The GPS is using just gound connected to Vss and TXD . BTW I try just connecting the GPS using the two pins to the PC and I get all the data expected.
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I more note, the same issue happens using a BS2sx and a BSP2
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Thanks for helping!

ktekx

I'm a little confused, but when you mention "the programming port just die," you are refering to the Stamp's serial port? Some GPS receivers require an additional pin to turn it ON before it can receive the coordinate data. I don't know if this is a simliar incident, but when I was first interfacing my own DigiTraveller GPS receiver, my PC would stop picking up the Stamp afterward as well (and I thought I fried either the PC's serial port or the Stamp) but then after a reboot, it apparently worked again.

Did you put a current limiting resistor between the Stamp and the GPS's TXD pin?

Toide

I actually figure out the cause of the problem but not why was happening. I was conecting pin 3 Tx to the Stamp instead of Pin 2 Rx. For some reason I was receiving and echo that looks like garbage. Still is unknow why the Stamp serial port stop working under that scenario.