LCD not working

[lee_smith_ljmu]

Hello, I have developed my code in flowcode V3 and tried it on the picmicrocontroller development board and every thing works. when i implement the PIC in to my prototype board the lcd display does not display the data. i have check the output from the pins, from a the PIC using a digital scope and compared these with the development board and they are the same. only the first line on lcd displays blocks and nothing else. do you know where i may get a better schematic of the pic micro development board especially for the LCd so that i can compare wiring.

regards

lee

[Benj]

Hello Lee

Sounds like your program is either not running on your hardware or is running at the wrong speed.

Top row of LCD is black = LCD has not been started correctly.

Try a simple program that flashes a LED every second.

Eg if you create the following Flowcode program.

While 1
{
LED on
Delay 1s
LED off
Delay 1s
}

This way you can confirm if your program is actually running on your hardware and also if the clock speed and chip configuration settings in Flowcode are correct for your hardware.

[lee_smith_ljmu]

Hello,

I have changed my pic program so that an L.E.D flashes every second and when implemented into the prototype it works. from this i now know that my hardware set up is correct on the PICMICRO side. i still have a problem when connecting the LCD to the pins of the PIC Micro. Only the First line of the LCD displays black blocks. i am guessin that this means the LCD has not configured.

my pin connections in simulation using flowcode v3 are:

D0 - PORTB PIN 21
D1 - PORTB PIN 22
D2 - PORTB PIN 23
D3 - PORTB PIN 24

RS - PORTB PIN 25
E- PORTB PIN 26

when connecting to the PIC to the LCD in my prototype, the pins are

MICRO LCD
26 6 - E
25 4 - RS
24 14 -DB7
23 13 -DB6
22 12 -DB5
21 11 -DB4

1 0V (VSS)
2 5V ( VDD)
3 5V (Vo - CONTRAST)
5 0V (RS)

DB0 - DB3 ARE CONNECTED TO GND

My program works fine when on PICMICRO development board just not in my prototype board.
the only difference i can see are that the LCD in my prototype is 20*2 instead of 16*2 . would the dot matrix size produces any problems?
any ideas of how i cancorrect this would be great. many thanks

lee

[Benj]

Hello Lee

Have you tried adjusting the contrast, could be that its just set too high.

Other then that your connections all look ok. Have you checked conductivity of your tracks with a multimeter etc.

DB0 - DB3 should really be left individually floating rather then all shorted together to ground maybe this will help.

[lee_smith_ljmu]

Hi Ben,

I have check the conductivity of all pins and have tried connecting DB0-DB3 to ground and unconnected but yet there is still no joy.

I have also connected the LCD pins to the development board port B terminals blocks (where the onboard LCD works, with my program) still nothing works. all the pins connected as far as i could were correct. I know its going to be something little that is stopping it from working.

the LCD screen i am using is a 20 characters (5x8 dots) x 2 lines driven by a ’SAMSUNG’ KS0070BP-00CC which i believe is the same as the hatichi driver.

does the driver make a huge difference in operation? or the size(5x8 dots).

any ideas would be appreciated

lee

[Benj]

Hello Lee

Any chance the display your using is broken or damaged. If you put a high voltage into these devices they break quite easily. Make sure your supply voltages are limited to 5V. I know you can pick up these displays quite cheap from Ebay or Rapid if you want to try and get a second display to test.

The display is very likely to be compatible as I have yet to come across an alphanumeric display that is not compatible with our driver.

Pins DB0 to DB3 are all left floating on our board so this is the correct configuration. Tying these pins together and to ground could have possibly damaged the device.