Re: [Paparazzi-devel] a few technical questions about a home made LISA M V2

[Eduardo lavratti]

Are you using olimex Breakout board with original xtall ?
Its working ?

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Date: Tue, 2 Oct 2012 00:27:35 +0300
From: address@hidden
To: address@hidden
Subject: [Paparazzi-devel] a few technical questions about a home made LISA M V2

Hi.

I have a question about LISA/M for anyone that might know.

I have a spare stm32 olimex breakout board and i decided to use a breadboard

and make a FrankenLISA with some additional ic's like i have done with an LPC2148 breakout.

I now have reached to a point where i can load the firmware alright but looking at the LISA M v2 schematic the serial connection to the gps doesn't look good to me.

What i mean is that although the GPS has a 5v to 3.3v regulator the ublox module works on 3.3v logic but the LISA M v2 UART3 has the 10K pullup resistors tied to 5v by default, isn't this a little risky?

Should i ommit the 10k pull up resistors as i want the GPS to be powered from the 5v rail in order not to load the 3.3v CPU line but keep the serial i/o to 3.3v levels.

Also if i connect the UART2 pull up resistors to 3.3v keeping the UART2 Vsupply to 5v and use a voltage divider at the uart's rx pin (5v logic to 3.3v logic) can i connect a 9xtend modem (5v for 1W output) safely?

Chris

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