arduinoresetxbee
I would like to be able to reset an XBee with an Arduino by connecting the reset pin on the XBee to a General I/O pin on the Arduino. I'm wondering if any additional components (transistors, resistors etc.) are necessary between those pins.
I found this tutorial on ladyada, but it shows how to reset the Arduino with the XBee which is the opposite of what I'm looking for.
Schematic from the tutorial:
Yes, you should be able to use Arduino board as a Serial to USB converter. You don't even need the ATmega chip for that. Just connect the power and the TX/RX pins of the XBee to the corresponding pins on the Arduino board and you're good to go.
The nixie tube is essentially the same as a neon bulb with multiple cathodes. The wire cathodes are shaped into the numbers 0 to 9. To turn the electrode ON you need to supply a high voltage (of about 170 Volts DC)to the common ANODE (the see through grid). This will be through a current limiting resistor to give a current of about 2mA. When 'lit' the anode voltage will drop to about 140V (the maintaining voltage). You will need to check the actual figures for your chosen nixie tube.
To light the cathode you will need to switch it to ground (0v) through a transistor or other suitable switching device.
This could be done by switching each cathode with a single I/O line (through suitable transistor etc.) but with three nixie tubes you would quickly run out of lines.
This is where the 74141 comes in. It is a BCD decoder 1 of 10 outputs designed to switch the cathodes of the nixie to ground. This requires FOUR I/O lines per digit (nixie tube). This chip also ignores non valid numbers (1010 - 1111) and blanks the display.
You could drive this chip directly from the arduino OR you could add some 4 bit latches between the arduino and the 74141 avoiding the need to tie up the I/O lines or multiplex the display.
Health and safety warning - High voltage hurts and destroys arduinos if you're not careful.
Best Answer
The reset pin is bidirectional, and default configured as open-drain with a pull-up resistor (datasheet page 13). That means that you can assert Reset by making that pin low.
Don't make the Arduino's output high to de-assert Reset! Two reasons:
So to de-assert Reset switch the Arduino I/O pin to input. Make sure the ATmega's internal pull-up is disabled! The Xbee's pull-up resistor will take care of the proper high level.
To interface the 3.3 V Xbee safely with the 5 V Arduino you can use LadyAda's adapter which has a level shifter.