Show Posts
Pages: 1 ... 30 31 [32] 33 34 ... 44
466  Using Arduino / Networking, Protocols, and Devices / Changing default settings with my new MatrixOrbital LCD on: April 15, 2011, 01:44:12 pm
I have gotten my I2C LCD to work if I temporarily short the reset pins.  My test sketch does things like print "hello world", it turns the backlight on/off, shows seconds counting...  It all works.  But when I power down the display and then power it up again, nothing works.  But, shorting pins 3 & 4 when I first power it up, makes it work.
I understand that this manual override changes the baudrate, & I2C address.  Evidently one of them is not correct.
The manual for my LCD:
http://www.matrixorbital.ca/manuals/LK_series/LK162-12/LK162-12_Legacy/LK162-12_220.pdf

It says,
Quote
Manual override should only be required in one instance. If for some reason the module is set at a baud rate
which cannot be produced by the host system and all communication to the display is lost, then the user
should follow this simple procedure:
1. Turn off the display
2. Put a jumper on pins 3 and 4 of the keypad connector (R3 and C1).
3. Power up the display. The baud rate is now set to 19,200.
4. Remove the jumper and change the RS-232 port settings to the desired baud rate.
5. Turn off the display.
6. Power up the display.
Refer to the “Set RS-232 Port Speed” command (section 6.1.14) for acceptable baud rates.



So I look at section 6.1.14:
Quote
6.1.14 Set RS232 port speed (254 57 [speed])
This command sets the  RS232 port to the specified [speed]. The change takes place immediately. [speed] is
a single byte specifying the desired port speed. Valid speeds are shown in the table below. The speed can
be manually reset to 19,200 baud in the event of an error during transmission (including transmitting a value
not listed below) by setting the "manual override" jumper on the module during power. This command is
ignored until this jumper is removed again.
Speed Value Speed
FF Hex 1200 baud
81 Hex 2400 baud
20 Hex 9600 baud
0F Hex 19200 baud

...but how do I do that?  I'm using a library, so I don't really know how to do this manual sending of commands.

Here's the library:
http://arduino.cc/playground/Code/LCDi2c
...the link on that page is broke: the library for the LK162-12 is here:
https://public.me.com/digid

In the documentation it says you can do unsupported commands with this:
Code:
command(command) Write a command not supported yet in the library to the display

I can't figure out how to do this...

Extra info: My test sketch that works when I short pins 3 & 4 for manual override
Code:
#include <Wire.h>
#include <LCDI2C_LK162-12.h>
LCDI2C lcd = LCDI2C(16,2,0x50,0);             

void setup(){
lcd.init();
delay(10);
lcd.clear();
lcd.set_contrast(255);
}

void loop(){
  lcd.clear();
  lcd.print(" WELCOME FOLKS!");
  delay(2000);
  lcd.clear();
  lcd.print(millis()/1000);
  lcd.print(" seconds now...");
  delay(1500);
}
467  Using Arduino / Motors, Mechanics, and Power / Re: Pull down resistors keep motors disabled during power-up on: April 12, 2011, 11:52:53 pm
Yes.  When the Arduino starts up the pins are inputs (apart from TX and pin 13) which means they will float.  A pull down of 10k will be fine.

When the pins are output they can source 20 to 30mA if necessary to overcome any pull-downs so 10k is neither here or there.

However the internal pull-up resistors on the Arduino are between 20k and 50k I think.  Best to have your pull-downs an order of magnitude smaller than that, namely 2k2, to ensure they always 'win' should the pins be configured as inputs with internal pull-ups.  That's still only 2.3mA load.

...thanks, that helped me understand what's happening a little better.
468  Using Arduino / Motors, Mechanics, and Power / Pull down resistors keep motors disabled during power-up on: April 12, 2011, 01:08:44 am
Code:
Pull down resistors keep motors disabled during power-up
I see the Adafruit motor shield says this.  Can I add 10K resistors  to my SN754410 on pins 2 & 7 that connect to my Arduino and keep the motor from turning on at startup?
If my 2 motor control pins are 10 and 11, then I'd just add in two 10k resistors from 10 & 11 to ground? That won't interfere with the normal motor operation?
thanks
469  Using Arduino / Motors, Mechanics, and Power / Re: Anyone familiar with the SN754410 on: April 11, 2011, 10:08:56 pm
hmmm.  That's not the answer I hoped for!  smiley-roll
I reckon I'll work in some extras...
470  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
471  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?
472  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!
473  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
474  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?
475  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...
476  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.
477  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...
478  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.
479  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.
480  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...
Pages: 1 ... 30 31 [32] 33 34 ... 44