Olimex Support Forum

Others => UEXT => Topic started by: rgardus on July 15, 2013, 08:05:27 PM

Title: MOD-GPS
Post by: rgardus on July 15, 2013, 08:05:27 PM
Hi All.

I am using a MOD-GPS connected directly to UEXT connector of a PIC-WEB board. It works ok, when it works.
I have a strange issue. The MOD-GPS is not starting (the litle red led inside is not lit) when I am first connecting power to the PIC-WEB board. If I am shortly disconect de power and reconect the MOD-GPS is started.
I have tryied to apply 5V from the 12V straight to the MOD-GPS (I have a multi-output power supply).
It is the same situation.
Can somebody help me whi this is happened? I have modified UART_TO_TCP to send GPS NMEA messages on a TCP/IP socket. Is something else that I have to do first to select the UEXT as UART?
Please help :)
r
Title: Re: MOD-GPS
Post by: LubOlimex on July 16, 2013, 09:49:50 AM
Hello rgardus,

This might happen due to initial capacitance on the UEXT lines. The PIC-WEB+MOD-GPS might draw too much current initially when the power is applied. After few seconds when the capacitors are charged the current draw drops.

Best regards,
Lub/OLIMEX
Title: Re: MOD-GPS
Post by: rgardus on July 16, 2013, 12:27:01 PM
OK. But what can I do? I have already powered the MOD-GPS from another power supply.
Is there something else that I can do?
Title: Re: MOD-GPS
Post by: LubOlimex on July 17, 2013, 03:28:42 PM
Hello rgardus,

The correct way of powering a host board + mod board is to power them when they are already connected via the UEXT cable.

Best regards,
Lub/OLIMEX