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LeonvB  
#21 Posted : Sunday, November 27, 2011 4:13:13 AM(UTC)
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Quote:
the guide says an additional load of 75ma can be drawn from DVCC from the I2C header

I think you didn't read it correctly. To my knowledge the guide never links DVCC to the I2C header.
sureshm  
#22 Posted : Sunday, November 27, 2011 1:17:54 PM(UTC)
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Totally agree the guide never explicitly links DVCC and I2C header. BTW I really appreciate what you have done with the guide. One of the best written DIY guides.

The 'Lay-out of Buffalo II module' on page 3 labels the power supply for I2C as DVCC. Also, the the I2C supply is 3.3V, so since VD is ~5v, I assume one of the tridents must be supplying it?
LeonvB  
#23 Posted : Sunday, November 27, 2011 3:02:05 PM(UTC)
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Quote:
The 'Lay-out of Buffalo II module' on page 3 labels the power supply for I2C as DVCC

The BII has on-board lineair regulators. I don't know how Russ routed the board, but I think you'll find one of them (the one for the digital circuit, hence DVCC) is the source for the I2C header.
sureshm  
#24 Posted : Sunday, November 27, 2011 4:11:20 PM(UTC)
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Without tridents installed, I suspect that the on-board linear regulators would power the I2C.

Russ, could you please confirm if tridents are installed (and hence bypassing the linear regulators), the power for I2C does come from the tridents? My DMM suggests there is a path from the DVCC trident to the I2C supply.
Russ White  
#25 Posted : Monday, November 28, 2011 8:18:16 AM(UTC)
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The I2C header has a pin for optionally utilizing the DVCC (3.3V supply) if the Tridents are installed they are the DVCC supply. The linear regulator is not powered when using the Trident.
sureshm  
#26 Posted : Monday, November 28, 2011 9:28:05 AM(UTC)
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Thanks Russ.

So with provided 20 ohm current resistor for DVCC trident, can you still draw 75ma from I2C header or would it need to be lowered? (~1.2 Volts across R4 @ 20 ohm give 60ma).
Russ White  
#27 Posted : Monday, November 28, 2011 10:56:58 AM(UTC)
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It would definitely need to be lower. :) The 75ma reference only relates to using the stock configuration.

The Trident should still be more than able to drive volumite.
sevan86  
#28 Posted : Wednesday, July 17, 2013 2:42:05 PM(UTC)
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If by using jumper wouldn't create an issue other than filtering, I would go with the jumper but I kind of doubt it. Has anyone tried doing that yet? Eventhough 20 ohms and jumper wire aren't much different but still.....

pcb assembly quotes

Edited by user Tuesday, July 23, 2013 5:39:10 PM(UTC)  | Reason: Not specified

Brian Donegan  
#29 Posted : Wednesday, July 17, 2013 4:53:50 PM(UTC)
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Originally Posted by: sevan86 Go to Quoted Post
If by using jumper wouldn't create an issue other than filtering, I would go with the jumper but I kind of doubt it. Has anyone tried doing that yet? Eventhough 20 ohms and jumper wire aren't much different but still.....


You cannot use a jumper for R4. If you have v3 Tridents, then you do not need to add R4, as there is an SMD R4 already in place to set the current for the Buffalo.
Russ White  
#30 Posted : Thursday, July 18, 2013 12:40:44 AM(UTC)
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Yes jumping R4 would be a surefire way to kill your Trident. :)
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