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Old Mar 06, 2013, 08:05 AM
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Quote:
Originally Posted by Dennis Frie View Post
Cool thanks, bob has bigger sized crystals in his shopping list
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Old Mar 06, 2013, 08:08 AM
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Year just noticed. Itīs close and will probably work, but I will PM him later
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Old Mar 06, 2013, 12:57 PM
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Just a few clips.
OSD_v16_3 (1 min 41 sec)
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Last edited by Dennis Frie; Mar 06, 2013 at 02:23 PM.
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Old Mar 06, 2013, 02:44 PM
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27Mhz Crystal

Quote:
Originally Posted by Legot View Post
It doesn't...

However, it does have internal capacitors for the pierce oscillator...
@ Dennis --- I am confused (easily actually). I have looked at OSD board pictures and the BOM you keep pointing too. Granted the pictures may be dated but, the latest BOM link you keep giving up lists a ---- 27MHz Crystal. See:http://www.bobsquads.com/MAX7456-DIY-OSD.html

Here is a cut-n-paste from the datasheet @ http://datasheets.maximintegrated.com/en/ds/MAX7456.pdf

As I see it refers to the oscillator as though it is already internal...

"Crystal Oscillator
The internal crystal oscillator generates the system
clock used by the video timing generator. The oscillator
uses a 27MHz crystal or can be driven by an external
27MHz TTL clock at CLKIN. For external clock mode,
connect the 27MHz TTL input clock to CLKIN and leave
XFB unconnected.

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Last edited by bstott2; Mar 06, 2013 at 03:06 PM. Reason: Added link to datasheet and cut-n-paste text.
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Old Mar 06, 2013, 02:47 PM
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Quote:
Originally Posted by bstott2 View Post
@ Dennis --- I am confused (easily actually). I have looked at OSD board pictures and the BOM you keep pointing too. Granted the pictures may be dated but, the latest BOM link you keep giving up lists a ---- 27MHz Crystal. See:http://www.bobsquads.com/MAX7456-DIY-OSD.html

You will need 1 x 27MHz crystal for MAX7456 and 1 x 16MHz crystal for Atmega328.

If anything else have been mentioned anywhere, please let me know, so I can correct it.
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Old Mar 06, 2013, 09:08 PM
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when I made the BOM I took the info from the render which stated the crystals were ABM7 which is the Abracon crystal. As big as the pads are, I do not think .5mm on each side is going to create a problem if you use the ABM7 units.

Having an issue w/ excel export.....

for the exact ones Dennis lists, digi-key part numbers:
16MHz = 887-1086-1-ND
27MHz = 887-1093-1-ND

Sorry about that.
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Old Mar 07, 2013, 12:33 AM
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Are the crystals with the updated part numbers smaller than the original BOM?
They were a problem for me to solder on because they were the same size as the pads, even a little bit bigger. Hard to get solder underneath. Have to try re-flow for the next ones!!
Bill
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Old Mar 07, 2013, 12:37 AM
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Dennis, in your clip you turned on the AH for just a short time. It looked reasonable there. How are the AH routines coming?
Bill
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Old Mar 07, 2013, 04:34 AM
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The larger (3.2 x 6mm) SMD crystals will 'just' fit on the pads but you will need a hot air station or similar to flow the solder.

Also be aware that some 16MHz crystals need different value load capacitors - mine needs 12pF and not 22pF as per Dennis' original spec.
Will this load cap change affect the Atmega?

Nigel.
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Old Mar 07, 2013, 06:14 AM
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You are best off getting the right caps for your crystals. I've had incorrect values give me ridiculous timing errors, half the time the Atmega will fail during startup, and even if it doesn't the SPI timing won't work at all.
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Old Mar 07, 2013, 08:22 PM
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OSD parts ordering

Hi - I'm ordering goodies! I setup a project at Mouser.com for DF's DIY MAX7456 OSD. The Mouser project name is: DF_OSD-DIY_MAX7456 3/7/2013.

If you want easy ordering go to: http://tinyurl.com/DF-MAX7456

At Mouser DF's OSD parts cost is ~ $31.13 (USD)

I had to swap the original Yageo 75Ohms resistors - Mouser was out. I substituted the same characteristics from Bourns and cheaper at $0.05ea (USD).

The resistor is 75O Resistor 1% 805 2 CR0805-FX-75ROELF Bourns CR0805-FX-75ROELF RES 75.0 OHM 1/8W 1% 0805 SMD.

Mouser also had alternate part no.s for the 3.3K & 1K resistors.

See the Mouser Project page to compare with Bob's BOM: http://www.bobsquads.com/MAX7456-DIY-OSD.html

Hope this helps.
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Old Mar 08, 2013, 04:29 AM
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I can post BOM links from Farnell (slovenian links but I think you can change language)..
I already sent to some shop, but they haven't contacted back yet ...maybe they had too much work with all the stuff
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Old Mar 08, 2013, 08:34 AM
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Quote:
Originally Posted by bob4432 View Post
when I made the BOM I took the info from the render which stated the crystals were ABM7 which is the Abracon crystal. As big as the pads are, I do not think .5mm on each side is going to create a problem if you use the ABM7 units.

Having an issue w/ excel export.....

for the exact ones Dennis lists, digi-key part numbers:
16MHz = 887-1086-1-ND
27MHz = 887-1093-1-ND

Sorry about that.
No worries, I didn't notice it either
Thanks for the updated part/numbers. Anyway possible I can ask you to edit the list?

Quote:
Originally Posted by SupraGo View Post
Are the crystals with the updated part numbers smaller than the original BOM?
They were a problem for me to solder on because they were the same size as the pads, even a little bit bigger. Hard to get solder underneath. Have to try re-flow for the next ones!!
Bill
The crystals I have used are a bit smaller, so that probably explains the problem you had when soldering. The smaller crystals should be a bit easier to solder
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Old Mar 08, 2013, 08:41 AM
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Quote:
Originally Posted by SupraGo View Post
Dennis, in your clip you turned on the AH for just a short time. It looked reasonable there. How are the AH routines coming?
Bill
The AH-routines haven't been changed since they was originally implemented
That's still one of the features that will need an update.

Quote:
Originally Posted by Devonboy View Post
The larger (3.2 x 6mm) SMD crystals will 'just' fit on the pads but you will need a hot air station or similar to flow the solder.

Also be aware that some 16MHz crystals need different value load capacitors - mine needs 12pF and not 22pF as per Dennis' original spec.
Will this load cap change affect the Atmega?

Nigel.
Please be aware, that the load-capacitance stated in the datasheet, does NOT mean that you should use xx pF load capacitor. The 2 capacitors are connected in series and you have to take parasitics into account as well. Please find a design-note or similiar. 18 pF caps will most likely be a good candidate for 12 pF load
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Old Mar 08, 2013, 08:45 AM
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Quote:
Originally Posted by bstott2 View Post
Hi - I'm ordering goodies! I setup a project at Mouser.com for DF's DIY MAX7456 OSD. The Mouser project name is: DF_OSD-DIY_MAX7456 3/7/2013.

If you want easy ordering go to: http://tinyurl.com/DF-MAX7456

At Mouser DF's OSD parts cost is ~ $31.13 (USD)

I had to swap the original Yageo 75Ohms resistors - Mouser was out. I substituted the same characteristics from Bourns and cheaper at $0.05ea (USD).

The resistor is 75O Resistor 1% 805 2 CR0805-FX-75ROELF Bourns CR0805-FX-75ROELF RES 75.0 OHM 1/8W 1% 0805 SMD.

Mouser also had alternate part no.s for the 3.3K & 1K resistors.

See the Mouser Project page to compare with Bob's BOM: http://www.bobsquads.com/MAX7456-DIY-OSD.html

Hope this helps.
Looks good
Mind if I attach your BOM to post #1 as well?

The resistors can pretty much be "any resistor". I recommend 1% for the 3.3K and 10K resistor used for voltage-divider, but except for that the values and ratings are not very critical.
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