Anyone used a uLCD-320-PMD2 display from 4D Systems?
T&E Engineer
Posts: 1,396
I used the BS2 demo program for the oLED-128-GMD1 that Parallax sells. The coding is almost identical to the uLCD-320-PMD2. However, I did make 1 modification to the LCD Display Control Function "Y" or $59.
· ' SEROUT TxPin, Baud, [noparse][[/noparse]"Y", 2, 15]··· ' Contrast High
··· SEROUT TxPin, Baud, [noparse][[/noparse]$59, $01, $01] 'LCD Display 1
...as contrast is not implemented into the LCD version yet. So I modified the command to turn on the LCD Display.
However, whether the line is modified or not, all I see upon turning on power is the splash screen. How can I tell that it is even doing something?
I am using the 2 pull up resistors tied high from P10 and P11 as well as the inline 1K resistor as stated in the manual. However, it does not tell me what to do with the RESET line so it is not connected.
If you can, please help.
I don't see anything else wrong with the setup or program.
Thanks.
· ' SEROUT TxPin, Baud, [noparse][[/noparse]"Y", 2, 15]··· ' Contrast High
··· SEROUT TxPin, Baud, [noparse][[/noparse]$59, $01, $01] 'LCD Display 1
...as contrast is not implemented into the LCD version yet. So I modified the command to turn on the LCD Display.
However, whether the line is modified or not, all I see upon turning on power is the splash screen. How can I tell that it is even doing something?
I am using the 2 pull up resistors tied high from P10 and P11 as well as the inline 1K resistor as stated in the manual. However, it does not tell me what to do with the RESET line so it is not connected.
If you can, please help.
I don't see anything else wrong with the setup or program.
Thanks.
Comments
Any help here?
Without protection, I found that even a momentary reversal of polarity renders the device forever useless.
Thus is the nature of LCDs - many subtile differences in format and operation in a very sensitive package. In sum, it is very hard to appraise if there is damage or defect.
At $149.00 each, your vendor should be quite helpful and the safest resource.
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"Everything in the world is purchased by labour; and our passions are the only causes of labor." -- David·Hume (1711-76)········
Good news! It's highly unlikely that your display is damaged or defective. I tested your code on one of my 320-PMD2 displays and was getting the same results as you. When I tested the display using DockLight, the display responded as expected. I ran the test·script that I use for·testing for over an hour without a single failure.
Putting a scope on it pointed me to the problem (and the solution). The latest hardware revision of the 320-PMD2 appears to have some sort of protection circuit on the I/O pins. I'm not sure exactly what was changed, but the newest displays are different from the older models at the silicone level.
I will verify with 4D Systems, but here's the skinny. The 1K series resistor is no longer required for operation with 5V TTL (as you would find with the Stamps). I removed the resistor and connected the Stamp Tx pin directly to the display Rx pin and it works fine. I've been running your code for more than 3 hours without a failure.
If you try removing the resistor and it damages the display, I will send you a new one at no charge. I will cantact 4D Systems and get the details about this change and we will probably end up removing the·verbiage about the necessity of a current-limiting resistor for 5V TTL circuits.
About your code.·All uLCD-23-PMD2 commands that contain·X and Y screen values·(in your code, the "S" and "t" commands) require·two bytes for the Y value (msb,lsb). Your code:
SEROUT TxPin, Baud, [noparse][[/noparse]"S", 30, 90, 2, yel1, yel2, 3, 3, "BIG",0]·needs to be changed to:
SEROUT TxPin, Baud, [noparse][[/noparse]"S", 30, 0,90, 2, yel1, yel2, 3, 3, "BIG",0]
Likewise, the "t" commands like the following:
SEROUT TxPin, Baud, [noparse][[/noparse]"t", "5", 90, 8, grn1, grn2, 2, 2] need to be changed to:
SEROUT TxPin, Baud, [noparse][[/noparse]"t", "5", 90, 0,8, grn1, grn2, 2, 2]
making the code changes above and removing the 1K series resistor on the Stamp Tx to display Rx line should solve the problem. I've attached the revised copy of your demo code.
have fun, don't worry.
Am I going to get sent a new display soon?
Can you try one more thing depending on whether you're using your original code or the code I most recently attached. Please check to see that the initial PAUSE statement (before the AutoBaud command) is a least 1 second. I set it to 500 Ms in the code I attached and found that it works OK when you load the code from the IDE because of the inherant delay while loading, but doesn't work if you just turn the Stamp off (I'm using a BOE) and back on again unless it's at least 1 second.
If that doesn't fix the problem, send me the display that you're having trouble with and I'll send you the one I used for testing today. I know that one works. PM me if you need the mailing address.
Steve
Post Edited (Duffer) : 9/24/2007 2:30:01 AM GMT
It's a bit ironic as today is my birthday and it was a gift to myself (via my wife's approval) - but yet I am sending it back on my birthday. No worries - just ironic.
Sorry to hear that you have to send it back. 9 times out 10 [noparse][[/noparse]or more] the problem is a software oversight. But as displays get smarter and smarter, it is harder to tell unless the supplier generates reliable test code for you.
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"Everything in the world is purchased by labour; and our passions are the only causes of labor." -- David·Hume (1711-76)········