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3091  Using Arduino / Microcontrollers / Re: Breadboarded ATMega328 not responding on: June 16, 2011, 12:04:42 pm
I don't see any bypass capacitors....

Don
3092  Using Arduino / Displays / Re: Hints for using Pololu Alphanumeric LCD Display 16x2 + BL on: June 11, 2011, 01:26:57 pm
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I guess since it is a parallel and looking at the summary I need at least 10 I/O pins to use it.
You would need 10 I/O pins only if you were using the simpler to program '8-bit' interface.  Since you will probably be using a prewritten library such as LiquidCrystal you can use the simpler '4-bit' interface which uses only 6 I/O lines.  This is the interface that virtually all of the tutorials use.  I would suggest that you follow the tutorial at http://www.ladyada.net/learn/lcd/charlcd.html.

Don
3093  Using Arduino / Displays / Re: TC2004a on: June 09, 2011, 05:36:22 pm
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...is the top bus rail on my plugblox (or what ever there called)
It's called a 'solderless breadboard'.

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The top 2 rails don't run the whole way
Some do, some don't...

Don
3094  Using Arduino / Displays / Re: TC2004a on: June 08, 2011, 03:32:30 pm
It should work if you do everything correctly.  Try following the tutorial at http://www.ladyada.net/learn/lcd/charlcd.html.  Don't skip any steps and don't proceed to the 'Bus Wiring' section if you don't get the single row of blocks (two rows in your case) about midway through the tutorial.

Don
3095  Using Arduino / Displays / Re: LCD only turns backlight on - No Text on: June 07, 2011, 07:20:18 pm
You don't use a fixed resistor here you use a potentiometer, typically 10K but not at all critical.  There's a diagram at the bottom of page 2 of the extended datasheet.  Have you seen the tutorial at http://www.ladyada.net/learn/lcd/charlcd.html?

Don
3096  Using Arduino / Microcontrollers / Re: Help with schematic: ICSP with ATMEGA328-AI and resonator. on: June 07, 2011, 05:31:13 pm
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It's not correct for the 28 pin DIP-version, but agrees with 32 pin TQFP-SMD version.

I missed that since I haven't used anything except DIP version.  I wonder which version the OP is using?


Don
3097  Using Arduino / Microcontrollers / Re: Help with schematic: ICSP with ATMEGA328-AI and resonator. on: June 07, 2011, 11:23:02 am
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I just want to post a picture of my schematic to see if you guys can spot something hooked up wrong.

Your diagram shows a 'MEGA8-AI' for the processor number but your subject line indicates you are using an 'ATmega328-AI'.  I can't find a datasheet for either of these devices (with the AI suffix), but the pin numbers on your diagram do not match either the ATmega8 or the ATmega328.  Which one of us is confused?

Don
3098  Using Arduino / Microcontrollers / Re: Help with schematic: ICSP with ATMEGA328-AI and resonator. on: June 07, 2011, 11:02:30 am
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Also if your not using serial (AND HAVE A BOOTLOADER) - connect Rx and Tx to GND.

Would you care to explain your reasoning behind this recommendation?

Don
3099  Using Arduino / Displays / Re: LCD only turns backlight on - No Text on: June 07, 2011, 09:19:46 am
The potentiometer is used to adjust the contrast by varying the voltage at pin 3.  The typical voltage required for a legible display is almost always less than 1 volt, frequently much less.  One typically uses a series resistor to get the required backlight current.  You do not want to apply 4.2 volts to the backlight as this voltage is dependent on the current.  You want to use a series resistor that will limit the current to the desired value (120 mA) and then the LED voltage will turn out to be about 4.2 volts.  If you divide the desired voltage across this resistor (5 - 4.2 = 0.8V) by the desired current through it (0.120A) you get 6.67 ohms.  I would start with a 10 ohm resistor.

Don

3100  Using Arduino / Displays / Re: Multiple LCDs on: June 06, 2011, 08:31:06 pm
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it works quite nicely with the arduino.

It may work nicely with the Arduino but it will be next to useless driving a LCD.

Don

EDIT:  The post to which this answer refers was removed.  It recommended an easy to use LED driver.  I guess I'll just have to quote the entire post in the future.

3101  Using Arduino / Displays / Re: 128 x 64 LCD Help!!!! on: June 06, 2011, 12:38:23 pm
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2 displays next to each other on one display

This is precisely the setup on many (all ??) GLCDs.  It is the selective enabling of the two chip select lines that determines which part of the display is used at any given time.  You would get the result you describe if the two chip select lines were tied together physically or if they were enabled simultaneously by your software.  I guess we need to see your sketch and a photo of the connections to determine the cause of your problem.

Don
3102  Using Arduino / Displays / Re: Multiple LCDs on: June 06, 2011, 12:30:00 pm
A link to the datasheet would really help.

Don
3103  Using Arduino / Displays / Re: controller K50070B on: June 05, 2011, 02:10:19 pm
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Does anyone know that the Liquid Crystal library compatible with lcd using K50070B

You will have more luck finding information on your controller if you search for KS0070B.  It's a Samsung controller that is compatible with the Hitachi HD44780U so your display should perform properly with the LiquidCrystal library.

Don
3104  Using Arduino / Displays / Re: Melabs 16*4 LCD on: June 05, 2011, 02:02:54 pm
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void loop()
{
 clearLCD();    Serial.print(" Hello");    delay(5000);
}
When dealing with the LCD, either by serial or parallel means, the display does not have to be refreshed.  Once you display information it will remain there until it is overwritten or until the power is removed.  Any information that is to be displayed and not subsequently changed should be dealt with in 'setup', not in 'loop'.

Don
3105  Using Arduino / Displays / Re: [solved] 16x4 LCD: Characters in row 3&4 are moved to the right on: June 05, 2011, 01:54:18 pm
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If my recollection is right, there are two ways to address the LCD onboard memory (DDRAM?) that stores characters in a 16X4 display, 20 bytes for one line, the same way as 20X4, or 16 bytes for one line. I don't think the library can tell which way so it simply looks at 2 or 4 rows and makes a decision that is compatible with most displays.

There's only one way to address the DDRAM in the LCD controller so there is no decision to be made by the library.  The real problem is that the same controller is used for all display configurations and there is no way to inform the controller as to which configuration it is driving.  Take a look at the link in reply #11 for the full explanation.

The problem here is in the cursor positioning, not in the storage of data in the DDRAM.  The library could be modified to actually use the information in the lcd.begin argument to correctly position the cursor for any display configuration.  I believe that John has already done this in his LiquidCrystal440 library.


Don
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