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Topic: MAX7456 and EM406 GPS in an OSD (Read 799 times) previous topic - next topic

whiteglint143

Hello, I am working on a project to make an on screen display for a model airplane that shows GPS information. I am using the MAX7456 as the OSD driver and an EM406 from sparkfun as the GPS. Following this thread: http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1220054359 I was able to upload an ASCII Font set to the Max7456 with my Uno. I am well aware that there has been others who have made an OSD from the 7456 but I want to learn how to do it instead of copying another persons work. I admit, I am using the two respective libraries because I am not experienced enough to write my own yet.

I am using the EM406 and NewSoftSerial library to get the data but it uses pins 2 and 3 for serial communication. (The EM406 shield appears to be hard wired to those pins)  And the max7456 VSYNC uses pin 2 for Interrupt 0, but it is not hard wired. I know the interrupts are only on 2 and 3 so I would need to rewire my GPS shield to two different pins and adjust it in my sketch. I know the GPS does not use pins 0 and 1 because the library uses those for outputting the serial data to the serial monitor.

My question is, what pins should I rewire the GPS to? Or is there a better solution? I tried to upload the code but the forum says it exceeds 9500 character length.

http://www.sparkfun.com/products/9168 (MAX7456)

http://www.sparkfun.com/products/10709 (GPS)

johnwasser


it uses pins 2 and 3 for serial communication. (The EM406 shield appears to be hard wired to those pins) 


There are two solder jumpers  (marked '2' and '3') on the top of the shield near the UART/DLINE switch.  Remove the solder to disconnect the DLINE side of the switch from D2 and D3.  Then jumper the DLINE switch side of those two jumpers to the data pins of your choice.
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whiteglint143

Ah, completely missed that. So it really is simple as this? And what is UART for? I am assuming it is for the Serial 1 and 0 pins?

Thanks!

johnwasser


And what is UART for? I am assuming it is for the Serial 1 and 0 pins?


Yes.  If you don't need a USB connection to your Arduino you can switch to UART and use the hardware serial port to talk to your GPS.
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whiteglint143

I soldered the wire on and it worked out last night. Now I just need to figure out how to display GPS data on the OSD. I had it display information from a wii nunchuck but when I go to use the GPS functions it doesn't display. I think it has something to do with the type of data the GPS outputs.I can post the code if anyone is willing to give it a look over

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