Going for some duplex
Imade some more temporary solder works to interface the Garmin. I will probably have to read through some more papers before I make a first attempt to send something down my "homebrew" line.
both ways
A simple transistor
A simple bc337 and two 2k resitors made everything work. Before that a had a go with a Maxim 222 Rs232 converter with no sucess. I hope the solution will work in the other direction towards the Garmin.
bc337
What will be next
It seems I made yet another mistake with the electrical interface to Garmin 620.Next time I will try with a balanced driver.Using a normal TTL driver made it go into self oscillation after a short while.
In need of a decoppling capacitor?
A minor step on the way is to get the inverter working, it seems like failed at the first try. I do get the NMEA sentences from the navigator but the output looks at times awful. Perhaps it is only a decoppling capacitor I need.
NMEA sentences
A poor output
temporary hardware
Some tiny soldering
I will interface the Garmin with ttl levels, so I needed to invert the signal.
Instead of going for the old 74 series I tried the tiny one logic circuit.
one gate logic
A new interface
My 9 years old Pocket PC desided to show the map in an inverse style sometimes this summer.
I desided to look for a new one and found the Garmin 620 which I will try to hook up to my Zigbee net thruogh my Mbed ARM.
Garmin
