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451  Using Arduino / Motors, Mechanics, and Power / Anyone familiar with the SN754410 on: April 11, 2011, 09:43:47 pm
http://www.sparkfun.com/datasheets/IC/SN754410.pdf

I'm not good at deciphering datasheets, but it seems like this chip has diodes in it that would work for kickback filters on my little Sparkfun gearmotor.
The diagram on page 2, where it says, "typical of all outputs". --wouldn't those 2 diodes on the right work as kickback diodes?
I'm trying to work kickback diodes into my pc board, but it would be SO much easier if I didn't have to...
thanks
452  Using Arduino / Networking, Protocols, and Devices / I2C LCD & Keypad on: April 05, 2011, 10:18:11 am
I really like the looks of this:
http://www.matrixorbital.com/Intelligent-Display-Character-LCDs/c39_3/p73/LK162-12/product_info.html

I've never worked with I2C before.  I see there are libraries for other keypad/lcd units like the one from byvac.  Would I be able to use this one from matrixorbita. with that library?  If not, would a person be able to get one of these units up and running with the Arduino?
453  Using Arduino / Displays / Re: Shiftreg alternate IC for SRLCD on: April 03, 2011, 11:26:05 pm
THANKS RARON!
I had given up in SRLCD--I thought I messed up somewhere on my home brewed pcb.  Finally just gave it up, but I tried the new schematic on my breadboard, and it's working great!
454  Using Arduino / Networking, Protocols, and Devices / Re: Bluetooth mate vs. Bluetooth modem? on: April 03, 2011, 09:04:52 pm
Sorry, I just keep thinking you guys know everything, and that you'll know exactly what I'm talking about...
http://www.sparkfun.com/products/9358
http://www.sparkfun.com/products/582
455  Using Arduino / Networking, Protocols, and Devices / Bluetooth mate vs. Bluetooth modem? on: April 02, 2011, 06:41:07 pm
What is the difference between the bluetooth modem gold, and the bluetooth mate gold??? Which would you want if for example you wanted to control your arduino remotely with your android phone to do something?
456  Using Arduino / Networking, Protocols, and Devices / Re: tx & rx pins doing double duty for keypad columns on: April 02, 2011, 05:12:06 pm
Results:
You can use the Serial connect to your pc even though two columns are connected to D0 & D1.
However, there can not be any instance of "Serial.whatever" in your code, or else those two columns will not work.  This is acceptable for troubleshooting.  If serial is needed, just uncomment Serial.Begin(9600), and insert the Serial.print command where ever you need it...
457  Using Arduino / Motors, Mechanics, and Power / Re: Driving a solenoid on: April 02, 2011, 09:24:57 am
Sorry, I just remembered you mentioned this just recently:
Quote
The resistor wired between the arduino output pin and the gate of the mosfet is to protect the output pin from large current spikes as the mosfet gate capacitance is charged or discharged initially when commanded on or off. Once the mosfet gate is fully charged or discharged there is no DC current flow from the output pin and the gate. This should be a rather small resistor value so as not to slow down the switching transition time too much, 300-1,000 is a good range to use.
458  Using Arduino / Networking, Protocols, and Devices / Re: tx & rx pins doing double duty for keypad columns on: April 01, 2011, 10:34:27 am
You can also connect a keypad to an analog port, - http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1170140545/4 -

Google for variations.

I just tried this last night.  With the said configuration, they are very reliable for digits 1 through 6, roughly, but the higher analog readings start getting messed up with some resistance from the keypad contacts (I think that is the problem).  I'm using SparkFun's 4x3 keypad, brand new.  For example, if I press key 4, I get a reading of 195, and no matter how lightly or hard I press it, it only fluctuates from 193 to 197, that's very close tolerance.  But if I press key 0 lightly or hard, I can get a reading from 890 to 940, roughly.  You see the problem.  I think I will try to figure out what resistor values are needed to get an analog reading span from 0 to about 500-600, sometime when I have a free hour or 2, unless someone knows how to calculated this in their head...
459  Using Arduino / Networking, Protocols, and Devices / Re: tx & rx pins doing double duty for keypad columns on: March 31, 2011, 10:44:46 pm
GREAT NEWS!
thanks.
460  Using Arduino / Networking, Protocols, and Devices / tx & rx pins doing double duty for keypad columns on: March 31, 2011, 10:35:36 pm
I have 2 of my keypad columns on pin D0 & D1.  If I need to use the serial monitor to troubleshoot something, would it still work?  It's the keypad ROWS that have pull-up resistors on them, so if a key on the keypad isn't pressed, there's nothing really attatched to pins D0-D1.
461  Using Arduino / Networking, Protocols, and Devices / Re: RN-41 bluetooth with an arduino on: March 31, 2011, 09:55:35 pm
Anyone else know if you can use the Uno's 3.3 v to power the Rn-41; the specs (see my previous post) kinda say 2 different things...
462  Using Arduino / Networking, Protocols, and Devices / Re: RN-41 bluetooth with an arduino on: March 31, 2011, 02:56:09 pm
What do these numbers mean?  will the RN41 run off the Uno's 3.3 supply?
463  Using Arduino / Networking, Protocols, and Devices / Re: RN-41 bluetooth with an arduino on: March 31, 2011, 12:51:17 pm
Thanks,
the 1N5819 is a Schottky diode, I thought?  I hope so, I've ordered some to use as motor pike shunts on my H bridge.
464  Using Arduino / Networking, Protocols, and Devices / Re: RN-41 bluetooth with an arduino on: March 31, 2011, 12:18:51 pm
Thanks, to make sure I got the diode right, I drew up a quick schematic: 

Do I need to ground RTS or CTS? or just leave un connected?
465  Using Arduino / Networking, Protocols, and Devices / Re: RN-41 bluetooth with an arduino on: March 31, 2011, 11:37:55 am
Trying to understand the schematic, and make the Rn41 work with the Uno.
  In the schematic I've attached from Sparkfun:
The part I've highlighted in BL:  Could that be replaced with the Logic Level Converter from SparkFun (http://www.sparkfun.com/products/8745)

The part highlighted in RD: Is that just a 3.3 volt power supply?  So the Uno has a 3.3 v pin, I could use, correct?

This is starting to all look pretty easy.

...what is the part I've highlight in GR? 

And lastly, There are 4 pins being connected, but I thought I'd just need Rx and Tx for a general purpose 'serial pipeline'?  Do I need rts & cts?
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