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Netduino Plus 2 and SerLCD LCD-09067

SerLCD

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#1 mcdonnej

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Posted 30 January 2014 - 02:32 AM

I'll start with the caveat that I'm still a novice at this, and am hoping someone will immediately know what I'm doing wrong based on the symptoms.

 

I have a Netduino Plus 2, firmware 4.2.2, and am attempting to send data to a 3.3v SerLCD LCD-09067, a 16x2 LCD.  I'm using Visual C# 2010.  When I send data, all I get is a set of parallel vertical lines in the first cursor position of the first line.

 

From the SerLCD datasheet, I've tried using the 254 commands to reposition the cursor and 124 commands to turn off the backlight--neither works.  Tried using both decimal and hex.  I've looked all over the forum without luck--it seems this should be really simple.

 

I've also tried keeping the board unpowered during Netduino boot, to avoid garbage characters being sent.  Still no luck.

 

The one thing that's occurred to me--does the Netduino 3.3v pin have enough power for the SerLCD board?  (I can't find my 3 volt battery pack at the moment, or would have tested this.)

 

After the program exits, if I leave everything turned on, after a couple minutes, additional vertical lines appear in the next cursor positions (6 more, at the moment).  Not sure if that's helpful or just spurious.

 

Thanks in advance for any help.

 

--John Mc



#2 jrlyman3

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Posted 31 January 2014 - 07:52 PM

I assume this is the LCD that Sparkfun is selling which uses 3.3V?  It sounds like a baud rate problem to me.

What code are you using to setup the SerialPort?  Are you setting the baudrate to 9600?  Are you hooked up 

to the right I/O pins?



#3 mcdonnej

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Posted 01 February 2014 - 12:07 AM

This is the 3.3 volt board.  9600, 8, None, and 1.  The only connections are power, ground, and D3 out of the Netduino (Com 2 Tx) to Rx on the LCD.  Seems like it couldn't be any simpler...

 

public static SerialPort serialLCD = new SerialPort(SerialPorts.COM2, 9600, Parity.None, 8, StopBits.One);

 

I was wondering about the power since the spec sheet says the board wants 60mA with the backlight on, and the Netduino pins are rated for 25mA.  Looking at others' comments on this LCD board, though, I haven't seen any reference to using external power, and the backlight seems quite bright.



#4 jrlyman3

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Posted 01 February 2014 - 10:07 PM

I don't think that power is an issue I run a 20x4 parallel display on my NP2 with no problem.  I did some experiments with a logic analyzer and your configuration works to send data out on D3.  The baud rate looks good too.  Note: I used a NP1 for the test but it should be the same :-).

 

According to the Sparkfun web site it should show a banner for half a second on power-up.  Do you see that?  Maybe the display is bad?  Maybe it's a 5V display, you're using the 3.3V pin for Vdd right?  May try 5V and see if you get the banner.



#5 mcdonnej

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Posted 02 February 2014 - 06:41 AM

I do get the banner.  Also found my 3.3v power supply.  Before I remembered that the power supply ground and serial Rx both needed to be common, the board went a little crazy and showed every symbol in the book all across both lines, but that suggests the display is capable of displaying the symbols.  I also noticed it isn't exactly two vertical lines--the rightmost line has one extra pixel sticking out of the right side.

 

Figuring I could've garbled the baud rate, I sent the 9600 baud reset (124 then r) during the splash screen display, but still no luck.

 

I'll ask at Sparkfun, too.  They might be able to identify if this is symptomatic of something.



#6 jrlyman3

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Posted 03 February 2014 - 02:43 AM

I'm glad to hear that the display is not dead. It still sounds like the baudrate to me.

 

Sparkfun says that you can send a control-R ('x12') in the first half second after the display powers up to reset the baudrate to 9600.  I think that the easiest way to do this is to use a continuous loop sending the 0x12 (serialLCD.WriteByte(0x12)).  Cycle power on the display a couple times and hope you get lucky.






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