Im thinking about making a standalone Arduino on a breadboard. But I got some questions I hope you guys can help me with. Im am planning to follow this tutorial.
I need to kind of capacitors: 10 uF and 22 pF. Does it matter whether these are electrolytic, tantalum etc?
I want to power the board from a barrel jack. Do I need anything else than the barrel jack it self?
The tutorial uses a Sparkfun FTDI board. I got this FTDI board lying around. It got the VCC and GND connection. But no RXD and TXD which the tutorial uses. Instead it got RXI, TXO, CTS and DTR. Can I use this FTDI board or do I need a new one?
Is it possible to make the standalone Arduino run at 3.3v like the Arduino Pro Mini 3.3v?
I need to kind of capacitors: 10 uF and 22 pF. Does it matter whether these are electrolytic, tantalum etc?
Electrolytic or tantalum will be OK for the 10uF. The 22pF will be ceramic.
I want to power the board from a barrel jack. Do I need anything else than the barrel jack it self?
The tutorial lists the 7805 regulator and other parts to give the 5V rail. Together with a barrel jack socket to match your power supply, that should be all you need. Check the voltage output of your supply is within the range shown in the tutorial.
The tutorial uses a Sparkfun FTDI board. I got this FTDI board lying around. It got the VCC and GND connection. But no RXD and TXD which the tutorial uses. Instead it got RXI, TXO, CTS and DTR. Can I use this FTDI board or do I need a new one?
This tutorial shows how to interface to those FTDI connections.
0 ) That tutorial has AREF connected to 5V. It's an error, don't connect the AREF, just leave it open.
1 ) The 10uF can be tantalium I guess. But a reverse voltage will break a tantalium.
2 ) No, but some power supplies can switch '+' and '-'. You could add a diode for protection. A diode from the barrel jack to the 7805 voltage regulator.
3 ) It's good. Something with 'RX' is the RX, and something with 'TX' is the TX.
4 ) Yes, but an Arduino runs normally at 16MHz and 5V. To make it run at 3.3V, you need to make it run at 8MHz (either with a crystal or with the internal oscillator).
If I get it right, you can buy a (fake/clone/compatible) Pro Mini 3.3V 8MHz for less than 5 dollars, and you have everything you need ?
Peter_n:
2 ) No, but some power supplies can switch '+' and '-'. You could add a diode for protection. A diode from the barrel jack to the 7805 voltage regulator.
Guess you mean a diode from the + side of the barrel to the board itself?
Peter_n:
4 ) Yes, but an Arduino runs normally at 16MHz and 5V. To make it run at 3.3V, you need to make it run at 8MHz (either with a crystal or with the internal oscillator).
So instead of using a 16 Mhz I would be using a 8 MHz and the board will run at 3.3v with the same ATmega328 chip? Will the input voltage then be 3.35-12v like the Pro Mini??
The Pro Mini does not use the 7805 but a newer and better chip, with a lower voltage drop.
The input voltage of the 7805 should be about 2 volts higher I think.
A 5V ATmega328p with 7805 should have at least 7V at the input.
A 3.3V ATmega328p needs a different voltage regulater anyway. I think that a 7803.3 does not exist. You can use the old LM317 or one of the newer low voltage drop regulators : https://www.sparkfun.com/products/526
With three AA batteries, you can power the ATmega328p chip directly without voltage regulator.
Please call it a ATmega328p chip, with a 'P' at the end. That chip is Arduino-compatible and the version without the 'P' is not.
The 'P' chip has 'PicoPower', it is more efficient and runs at lower voltages.
