On 2014-01-04 05:01, David Taylor wrote:
On 03/01/2014 19:58, Brian Inglis wrote:
[]
Instructions are on David Taylor's site at
http://www.satsignal.eu/ntp/FreeBSD-GPS-PPS.htm#usb
I simplified the wiring shown in the above link by connecting
all +5V power leads to pin 6 DSR.
[]
That's a good simplification, Brian.
But as RS-232 can be up to 25V (according to Wikipedia) how do
you guarantee than the GPS 18x LVC won't be damaged, and that
enough drive current is available from DSR?
I'd like to add your suggestion to my Web page, but I don't want
people damaging their GPS receivers by injudiciously following
your advice.
I was not clear - I connect USB power to DE9 pins 5/GND and 6/DSR(+5V)
and also connect the GPS GND and power leads to those pins.
As the GPS is connected as a DCE (comms/modem) where pin 6 is an output,
and the PC as a DTE (terminal/device) where pin 6 is an input, no RS-232
interface should have a problem with +5V input on DSR.
I skipped the PPS LED as I could not find any low current LEDs locally and
the 18x LVC 5V@90ma power requirement is close to the USB 5V@100ma limit.
Instead I used your http://www.satsignal.eu/software/net.htm#SerialPortLEDs
program (thanks for that) to check PPS on DCD, and Garmin snsrxcfg
http://www8.garmin.com/support/download_details.jsp?id=4053 to set up and
check the configuration and sentences generated.
--
Take care. Thanks, Brian Inglis
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