http://www.fastraxgps.com/showfile.cfm?guid=c6ffc2f1-9814-4b50-b9df-4610134b37b7
Do I need to connect the grounds on p.30?
18 of 'em!
Looks like a very simple circuit is required. Only 5 pins including ground. The inputs are 3.3v tolerant.
Simple voltage divider to go from 5v to 3.3v?
GND
1.8V
ON/OFF
SDA
SCL
How do I read/write the I2C data with Arduino if it's only 1.8v?
Logic level converter. The $12 shipping sucks...
Any other ideas?
Spec says I2C can be pulled up to 3.6V.
I bet pulling up to 3.3V from arduino would do just fine.
Yes on the grounds - make a nice ground plane for reception.
Trade off unit cost & shipping vs unit cost & shipping elsewhere, like the GPS at sparkfun
which only needs 5 connections.
Here is a version on a card in a box
http://www.ontargetmarine.com/node/16
Cool boat GPS link! I want to make one!
I already have the UC430 in my hands.
I don't understand.
I2C, don't I also need to receive the data which is only 1.8v from UC430 to the Uno?
Is this a stupid question?
Oh, I use a resistor to pull up 1.8v output to 3.3v which my 5V Uno can read?
It's my first time, please describe the circuit.
Yes, the boat GPS works nice.
I2C, pull up the SCL/SDA lines with 4.7K resistors to 3.3V so it looks like good 0s/1s to the arduino.
Same will be good 0s/1s to the GPS for sending it commands/configuration/wjhatever.
Simple enough. So the 3.3v thru 4.7k will be stronger than the 1.8v from the GPS and will pull it up without hurting it. That's what they mean by 3.3v tolerant? I thought it meant the input could handle 3.3 instead of 1.8v. I guess both? Does this work for every 1.8v component? Or does it depend on the internal resistance?
Can I test the circuit first, with only 5 wires, before I solder the 18 different pins to GND? It's really tiny, I don't want to screw it up. Can you believe it's the size of only 1/2 a dime! Talk about tiny, still using your 328 boards...
Yes, SCL/SDA pins will work from 3.3V pullup resistors.
Pullup voltage depends on the part; some can go to 5V, some 3.3. Review on case by base basis.
Check out I2C interface first, worst that will happen is you get crappy signal reception.
Funny, it doesn't look that small in the pictures - guess I was expecting it to be more LS00031 size.
Got any pics of the mini-uinos? Be interesting to see how you fitted them up.
Your boards are between projects right now. Remember I had to resolder a few pins cuz I screwed up the first time.
Yo dudes.. Another newbie here.
I have the uc430 GPS unit as well, trying to get it to work for testing purposes.
I have connected as follows:
VDD: Pin 9 (1.8 V)
GND: Pin 4,5, 10-15, 18, 19, 21, 22, 27, and 31.
RX: 25
TX: 26
Also: Pin 1, 2, 6, 7, 8 (in the datasheet it recomends to connect theese to GND when not in use...)
But why doesnt it work? -Is it becase the serial connection needs 5V to work?
Can someone help me with a conection diagram? to explain what they write in previous posts? I dont understand what you mean by "pul-up resistor" And how can you "pull up" a voltage from 1.8 to 3.3? I thougt you only got less voltage when adding a resistor to the circut ????
If i put 3.3 V in on Pin 9, wouldn't it damage the uc430 GPS unit?
I made a breakout board for this uc430 chip to get to the pins more easily. If I get a chance, I'll post a picture of it soon 
Thanks guys.
