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Messages posted by: esa1966
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Thank a lot for your explanation.

So, it seems that my FTDI has a problem because with the switch on 3v3 there is no voltage on the FTDI VCC PIN (nothing connected on FTDI).
That's why I asked the schematic to control what happen.

Point 1 : FTDI VCC output
In my point of view, it's not necessary to have a "MCP1703 LDO 3.3V regulator" on the FTDI board.
A Output of 5 Volt is enough as there is already a regulator on your MW that power the µP at 3v3.

Point2 : MW Schematic JP1
In fact, I was wondering because the MW schematic indicate VCC and not VIN on JP1.
So, I tough I need to set the FTDI on 3v3.
But it's not the case and the schematic might be adapted : "JP1 VCC" changed to "JP1 VIN" as it's really connected to VIN and not VCC.

Point3 : FTDI Switch.
Because I don't have the schematic and my FTDI doesn't deliver a output voltage with the switch on the 3V3 position I though that the switch is more like a "5 V INTERNAL POWER" and "EXTERNAL POWER"
I mean that the FTDI can power the MW or the MW can be powered externally.
That's how I will use it and I think it's a good feature.
In my case this switch can be labeled "Internal Power"/"External Power"
Design remark : It could be a good feature to authorize an external power. A JUMP could be added in serial with VCC output. Or if the regulator is suppressed, then the switch can do that work.

Point 3 : RX/TX level voltage.
As there is a regulator on the MW Arduino, then the µP will be powered with 3V3. And the µP RX/TX is at 3V3.
It seems logic that the FTDI you provide must be compatible with your MW.
While I understand that the µP is 5 V tolerant, that doesn't mean the trigger level will be correct.
So I have modified your FTDI to connect the FT232RL PIN 4 to PIN17 (I cut the connection to 5VCC).
Design remark : If there is a 3V3 output on the FTDI then the PIN 4 could be connected to the PIN VCC output so it will change the RX/TX level accordingly to the voltage output.

This is a feedback how I begin in the world of MW.
And as a beginner I'm certainly worrying too much.



I have powered the MW and realized that VCC on the JP1 (FTDI connection) is in fact VIN.
If I put 5VDC on VIN, I also have JP1 PIN VCC with 5VDC.
It's not clear on the schematic.

Point 2 : If I put 5VDC on VIN, then the logic for RX/TX is at 3V3 DC.
It's normal because the µP is powered by 3.3VDC.

Question for FTDI :
Possibility 1 :
If I select 3V3 on FTDI then the MW won't be powered by the FTDI (as no voltage is present on the output of the FTDI VCC PIN).
I have to power the MW with an external power.
But the Logic level on RX/TX/DTR is always 5V.
Can I connect to MW?

Possibility 2 :
If I select 5V, then the FTDI will power the MW. I don't need an external power.
But LOGIC LEVEL will be 5 V on RX/TX/DTR.

Question : is it a risk to blow the µP or is it 5V tolerant even if µP is at 3V3DC?

I just received the Anarduino Mini-Wireless and the Anarduino-FTDI USB<>UART Breakout Board.

I have several question :

1) Do you have the Schematic for the FTDI as I try to understand the Power Switch on FTDI board.
I connect the FTDI with a USB cable to the computer and I suppose, the power will come from the USB.
When I select +5V, I measure 5V between GND and VCC.
When I select 3V3, I don't measure a voltage between GND and VCC and Logic level on RX/TX/DTR is always 5V.
Is it normal?

From a schematic (https://github.com/adafruit/FTDI-Friend/blob/master/ftdifriendsch.png) the chip FT232RL has a PIN VCCIO to adapt the IO level volatge..

2) I suppose, that I can connect the MW to the FTDI and it will be powered by the USB.
Does the VCC coming from the FTDI made to power the MW?
I select 3V3 on FTDI and when I connect the MW, I have +/- 2.5 V between GND and VCC on FTDI (MW is not powered).
Is it a return from other PIN signal (RX/TX)?

3) I suppose, I can't select 5V because VCC doesn't go through the Regulator.
The regulator work with VIN.

In other words, must I absolutely power the MW through VCC.

4) In Arduino 1.6.0, what can I select for the board and for the Programmer?

thank for your help
Best Regards

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