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Topic: Ftdi with switchable power (Read 2073 times) previous topic - next topic


Anything wrong with this circuit, ftdi out with a switch that chooses between usb or power jack for ftdi vcc.


I'm sorry.  The labels in your schematic are just too small to see.  Since the switch is off by itself and is only connected by labels it is very hard to determine what it is you are trying to do or if you have done it correctly.

When you say "for ftdi vcc" do you mean the VCC power going into the FTDI chip or do you mean the VCC power being provided to the serial connector???

It looks like FTDI VCC is connected straight to USB power.  The switch seems to select between regulated 5V and something else but it isn't clear where the power is going because I can't read the label on that pin.

If you want to switch the FTDI VCC input between USB power and regulated Vin power you can use the Diecimila schematic which uses a movable jumper to do exactly that:

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Thank you John, I was concerned they were hard to read but I couldn't make it larger without distortion.

The vcc to the FTDI CHIP comes from usb, the usb 5v is split and goes to one leg of the switch the Vreg 5 v goes to another leg and depending on the switch flip the center pin sends the choice to the vcc pin on the FTDI connector.

Sounds like the circuit you suggested will be what I am looking at doing here and I will look thanks again for the eyes, sorry it was too small.


Yep, looking at the Diecimila its the same circuit with a switch instead of the jumper.

Thanks again.

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