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Topic: PCB design (Read 1 time) previous topic - next topic

BenedictMason

Jan 06, 2014, 01:00 am Last Edit: Jan 11, 2014, 01:46 am by BenedictMason Reason: 1
A

graynomad

#1
Jan 06, 2014, 05:03 am Last Edit: Jan 06, 2014, 05:08 am by Graynomad Reason: 1
Firstly, that's a seriously bad schematic, I'm having a lot of trouble following it. For example what voltage is VCC? That's not even clear unless I missed it somewhere.

Next question, what are all the 770k/1k voltage dividers for, it looks like you are interfacing to a serial EEPROM but a) they are available in 5v version so you don't need to reduce the voltage and b) 470 over 1 will reduce the voltage of a high to about 14 pico volts (ok so I'm exaggerating).

Your I2C buss has no pull up resistors, should have about 4k7 on SCL and SDA.

You have a lot of caps on headers that (probably) aren't needed, and yet none on the CPU itself.

How do you plan to communicate with the devices on the Bluetooh and UART header, software serial?

That will do for now, at this point there's no reason to look at the PCB as the schematic is far from ready.

I see a couple of references to antennas, if that's RF they may need special consideration on your PCB, normally one aims for a 50R impedance using 4 layers. That said people seem to get by with any old crap :)

______
Rob
Rob Gray aka the GRAYnomad www.robgray.com

BenedictMason

#2
Jan 07, 2014, 03:36 am Last Edit: Jan 11, 2014, 01:47 am by BenedictMason Reason: 1
A

graynomad

Guess you didn't really want any advice eh?

______
Rob
Rob Gray aka the GRAYnomad www.robgray.com

Coding Badly


At least the person did not label you with a scarlet-A.  I'm left wondering the significance of a black-A (well, it's more of a grayish-A on my monitor).

graynomad

Yeah go figure, no idea what the 'A' means. No loss to me (except a few minutes wasted time) but the name is remembered and will get no further help from this little black duck. I really hope he builds the board from that schematic :)

______
Rob
Rob Gray aka the GRAYnomad www.robgray.com

nickgammon


A


How to use this forum

See point 14.

Quote

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This sort of childish behaviour will lead to a ban. We don't have time to give lengthy answers and then be treated like this.
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