Hi,
I’m having a strange issue with a ublox-552 GPS receiver module (with TTL interface).
When supplied from a separate source (5V) and connected to a RS232 of a PC
(via level shifter interface), it works fine, i.e. has a fix after about a minute.
Also without RS232 connection, because a LED goes from ‘on’ to blink mode,
if a position fix is done.
However, it does not work when connected to a Foxboard, and supplied via the
Foxboard power supply. The Foxboard (a small Linux board, based an the CRIS CPU)
is supplied with 5V, and the GPS receiver is connected to it via a ribbon cable
(+5V, GND, RxD, TxD). The power source is the same as above in standalone mode.
The abservable voltage drop is a few milivolts, which is basically the voltmeter
tolerance. I do receive NMEA messages properly, but never get a position fix.
I suspected EMI problems, so I packed the Foxboard first in a tin foil coated
cardboard box, and then in a steel box (1mm wall thickness).
Both had no effect, i.e. no fix.
Has anyone some more experiences with the delicate points of this receiver ?
How can this board keep the receiver from working properly, while a PC
or notebook does not ?