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Mega + MAX7456 Breakout

Posted: Sun Jul 26, 2009 10:22 pm
by adr1an
Hi all. I'm horribly stuck with this breakout and wonder if anyone can offer some insight.

I have it hooked up to ports 50-53 and INT0 (D2) and am using the code supplied in the thread ... 4359/59#59 over at

As you can see described in that post from myself, I can get video pass-through working fine - I jsut can't generate any OSD and the module seems to loose sync regularly untill you touch near the GND pin on the connector block.

I dont have any pullups or other hardware - just the breakout going to a breadboard going to the pins on the arduino. From what I could makeout from the Schematics, everything is onboard and I should be able to generate an OSD by now!! :)

Any tips or suggestions from anyone that has used this board succesfully would be *massively* appreciated.

Thanks in advance!


Posted: Thu Jul 30, 2009 10:36 pm
by adr1an

I've tried with a 10k resistor tied between reset and V+ as a suggestion from the forums, but still no luck.


Posted: Mon Jan 04, 2010 3:03 pm
by sfe_kav
Hello, my problem my problem is over here.
i write code for spi interaction
ic can display OSD in internal sync or video from input in external sync (OSD I think must be present but not)

The problem - i cant read registers - read_reg allways return 0
OSD does not display in ext. sync (may be problem in black level - i must read default value set bit and next reset bit? but i cant read anything)

when video dark i can see grid on it but without any leters

any ideas?

Arduino 0017
Arduino Duemilanove
Self maded max 7456 brakeout


Posted: Mon Jan 04, 2010 3:32 pm
by sfe_kav
hehehe i change ntsc -> pal and can see OSD in external sync mode
but steel cant read registers

Posted: Tue Jan 05, 2010 8:41 am
by Liencouer
looking at your code i have not found anything glaringly wrong. your spi for loops go backwards, but you correct that with your bit_mask array being reversed. you have the MSB of the address set when reading from the registers, which is good.

the one thing i would suggest is to try and use the spi hardware instead of bit-banging it. take a look at

Re: Mega + MAX7456 Breakout

Posted: Mon Jul 05, 2010 11:23 pm
by yoppy

I can display OSD.
But, I also can't read the SPI register. Have you solved this problem?

I really need to read the register.

Thank you.