Author Topic: PreenF405 VCC Pin 64 / C1 Airwire  (Read 1097 times)

kreeper_6

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PreenF405 VCC Pin 64 / C1 Airwire
« on: May 03, 2019, 07:35:00 AM »
I ran a DRC on the F405 brd file in eagle and it is showing Pin 64 and C1 not connected to VCC, is this a bug? Connecting PC13 through a via on the bottom layer would reconnect the VCC floater.






served

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Re: PreenF405 VCC Pin 64 / C1 Airwire
« Reply #1 on: May 03, 2019, 11:59:52 AM »
Its related to your Eagle settings. Distances etc measurements. Make the numbers smaller and re.check.

kreeper_6

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Re: PreenF405 VCC Pin 64 / C1 Airwire
« Reply #2 on: May 04, 2019, 09:20:33 PM »
As far as I know, these distances are in the published brd file. I've seen that floater on various PreenF405 boards, there is nowhere for it to connect.

Xavier

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Re: PreenF405 VCC Pin 64 / C1 Airwire
« Reply #3 on: May 05, 2019, 05:58:07 PM »
Yes seems like VCC does not reach pin 64 of the MCU.
The 3 other VCC pins are enough to power correctly the stm32F4 as it's very stable in a preenfm2 usage.

Eagle 6.5.0 that i used for this PCB does not complain when runing DRC .
« Last Edit: May 05, 2019, 08:52:00 PM by Xavier »

rheslip

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Re: PreenF405 VCC Pin 64 / C1 Airwire
« Reply #4 on: January 11, 2020, 01:58:06 AM »
I noticed this as well. I added a jumper from pin 64 to 3.3v on the module. Don't assume that the 3.3v and GND pins on a semiconductor device are connected together inside the chip - in some devices they are not and you could be powering a section of the part through some parasitic internal path. Not good.