I just got the Arduino Pro Mini 3.3V and I am having a problem uploading to the board. I connected a 5 V supply to RAW and I used the sparkfun FTDI Cable 5V VCC-3.3V I/O to connect to the computer. I pressed the reset button.
I get this error:
avrdude: stk500_getsync(): not in sync: resp=0x00
avrdude: stk500_disable(): protocol error, expect=0x14, resp=0x51
After I connect the battery, the red LED lights up and green LED blinks rapidly at first and then stops. Is it even necessary to connect the external supply to the arduino in order to connect to the computer? The LEDs do not light up if I only connect the cable to it.
I’m very new to this–am I missing something? Thanks…
No external supply is needed when I use my 5v ftdi and pro-mini’s.
Are your components loading the supply down?
I don’t have anything attached to the arduino pro mini. I just connected the FTDI Cable from it to the computer, and the LEDs do not light up. not sure how to troubleshoot…
Did you use a 3.3v ftdi cable? I’m not so sure a 3.3v pro-mini can handle 5v.
I used the FTDI Cable 5V VCC-3.3V I/O http://www.sparkfun.com/products/9717
I thought this was the correct cable…
Okay, the site says it works with the 3.3v pro-mini.
The red led should light when power is applied to the pro-mini.
If it’s not either voltage isn’t reaching the regulator or the regulator is damaged.
P.S. you shouldn’t connect power on the raw input when you are programming.
You will have 3.3v on the output of the regulator and the same node will have 5v on the output of the ftdi cable.
wow I just found out what the problem was: I inserted a pin header that connects to the cable into the arduino programming header, and only soldered the end pins to hold it in place because it appeared that the other pins were making contact with the holes. But after soldering all the pins to the holes, the upload worked!
Thank you for your help. I have one more question: how come the 5 V on VCC created by the cable does not damage the board? I thought it had to be 3.3 V.
From what I understand the atmega328 can operate at voltages between 1.8 and 5.5v. The outputs will be at vcc when high. Now if you give it 3.3v on vcc, i’m not sure if putting 5v on it’s inputs would hurt the chip or not.
That’s good you got it figured out. I prefer the pro-mini over regular arduino. Works really well for all my breadboarded thing-a-ma-bobs.
Thanks! I was wondering if you could clarify one more thing!! :mrgreen:
On the arduino pro mini homepage, it says that VCC is for the regulated 3.3V or 5V supply (depending on the model), so I was wondering why having 5 V on VCC from the computer does not damage the arduino 3.3 V model. Also, I noticed that the 5 V model was out of stock–what’s the advantage of the 5 V model?
It’s the same chip (328p). If you give it 3.3v it’s outputs will be 3.3 when high. If you give it 5v, it’s outputs will be 5v when high. If you have sensors that work with 3.3v signals, it’s easier to use the 3.3v pro-mini (you won’t have to level shift the signals). Same goes for the 5v model. The only difference between the two is the on-board regulator. One is 3.3v the other is 5v.
From what I see the 5v model runs faster. (16MHz, I really don’t know why…)
The only problem I could see happening is like what I mentioned before.
If you put, say, 6v on the raw pin. This will supply 3.3v to the atmega via the regulator. Now you plug in 5v directly to the vcc pin (like your cable would do). The regulator is trying to regulate to 3.3v and now 5v is being put on it’s output. I don’t know what the consequences would be but I’m sure the regulator won’t be happy.