I run it at 3.15 - 3.25 VDC, instead of the nominal 3.00 VDC. That seems to give the required margin, because now it works every time. Since I use a laboratory power supply with my eTrex when it's connected to the computer, I simply turned the voltage up a little. But since I've had the same problem before, with other devices, I suspected what I described above. When I tried an external supply, to make sure it lasted during a long download, I had big problems. I had big problems downloading maps to my unit, unless I had new alkaline batteries inside it.
#BELKIN USB TO SERIAL ADAPTER NOT RECOGNIZED PORTABLE#
USB adapters are more often used with portable units, where they try to save as much power as possible. That doesn't seem to be the case with all these USB converters, but is usually true for stationary computers. That can work too, but it does require that either both ends do the same, or that one end is strong enough to drive the other one up to a proper level. Now some devices use the time framing of the RS232C specification, but uses TTL voltage levels. The specs say that a logical low (zero) is represented by a voltage of between +3 VDC and +15 VDC, something an eTrex unit just barely can meet.Ī logical high (one) should be represented by a woltage of -3 VDC to -15VDC, which the eTrex can't handle at all. I've had the same problem with my Sony Vaio and the Port Gear USB serial converter from Xircom, which I use with that machine.īut I assumed immediately that it was a voltage problem, since the 3 VDC power in my Vista can't give the proper voltage levels as the RS 232C specification requires. I saw this problem described in a Yahoo group too, where I responded, but what the.