OSEPP LCD Help
vangbe
Posts: 21
I just brought this a few days ago at MicroCenter and I don't know how to Send Information to it.
http://osepp.com/products/accessories/16x2-lcd-display/
It's on P0 - P 15
This is what I know..
P0 = VSS = Negative/Ground
P1 = VDD = Positive/Supply of 5 volts
P2 = V0 = Contrast Adjustment
P3 = RS = REGISTER SELECT SIGNAL
P4 = RW = READ/WRITE
P5 = E = ENABLE SIGNAL
P6 - P10 = 4 LOW DATA LINES
P11 - P14 = 4 HIGH DATA LINES
P15 = (Backlight+)
P16 = (Background-)
I hooked up P0 to VSS, P1 to VDD, P16 to VSS, P15 to VDD.
I can turn it on and off, but I don't know how to use the V0,RS,RW,E and the other functions. I also don't know how to code it to slowly turn on the backlight and turn off the backlight.
I'm using
' {$STAMP BS2}
' {$PBASIC 2.5}
http://osepp.com/products/accessories/16x2-lcd-display/
It's on P0 - P 15
This is what I know..
P0 = VSS = Negative/Ground
P1 = VDD = Positive/Supply of 5 volts
P2 = V0 = Contrast Adjustment
P3 = RS = REGISTER SELECT SIGNAL
P4 = RW = READ/WRITE
P5 = E = ENABLE SIGNAL
P6 - P10 = 4 LOW DATA LINES
P11 - P14 = 4 HIGH DATA LINES
P15 = (Backlight+)
P16 = (Background-)
I hooked up P0 to VSS, P1 to VDD, P16 to VSS, P15 to VDD.
I can turn it on and off, but I don't know how to use the V0,RS,RW,E and the other functions. I also don't know how to code it to slowly turn on the backlight and turn off the backlight.
I'm using
' {$STAMP BS2}
' {$PBASIC 2.5}
Comments
https://www.parallax.com/downloads/stampworks-experiment-kit-manual
https://www.parallax.com/downloads/stampworks-basic-stamp-source-code
Chris linked to the latest files.
I'm using the BoeBot kit btw..
The LCD I got is just because I want to try something out. If I'm correct, the board that comes with the BoeBot kit is different from the one that comes with the StampWorks kit
Speaking of which, many people actually get these LCDs working, but don't realize it because the contrast is so low they can't see anything on the display.
https://www.parallax.com/downloads/stampworks-basic-stamp-source-code
and download one of the files and used the "SW21-EX11-LCD_DEMO.BS2"
And this is my set up.. (ignore the LED and other wires)
For this specific code, I hooked up the..
- VSS pin to VSS
- VD0 pin to VDD
- RS pin to pin 3
- RW pin to pin 2
- E pin to pin 1
- A pin to VDD
- K pin to VSS
It's not working. Am I missing something?
Where am I suppose to connect the D0 - D7 pins?
Here's a diagram I found on the web which shows the connection for a parallax LCD. Notice the power and contrast connections? Also note the data pins?
P.S. - As a note, connecting pins 15 and 16 will always make the backlight come on, but the backlight is not controlled by nor connected to the display logic in any way. In other words, it isn't an indicator of anything working as far as the display itself goes. It's just some LEDs behind the display. Also note that quite often those pins need a series resistor to limit current to the backlight.
I was unable to get into the OSEPP forum and I didn't see a datasheet or instructions for this LCD.
Look at the wiring diagram on page 75 (85 of the PDF) of the StampWorks manual to see how the LCD data lines are wired to the BS2.
Notice that P4 goes to D4 (Pin 11 of your LCD), P5 to D5 (Pin 12), P6 to D6 (Pin 13), and P7 to D7 (Pin 14)
This uses only the 4 Data High lines and assumes your LCD uses the Hitachi HD44780 or is compatible.
The Parallax LCD documentation uses a 10K potentiometer to adjust the contrast.
Perhaps I just don't know how to read the schematic.
Is their a site to help me better my understanding on that particular area?
From my understanding of that photo, I'm assuming D7 is suppose to be connected to P7 & VSS (ground)? Correct? or is it suppose to be connected to ONLY P7? All the Greens are confusing me..
I'm not interested in fixing the contrast with a potentiometer. I was hoping I can dim the contrast a bit with only the programming; if possible.
Only the crosses with dots are connected together, so D7 is NOT connected to VSS.
You could use a Digital Potentiometer to control the contrast from your program, but doing so would take a few more I/O lines.