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#62873 I2C LCD character interpretation shifted by half a character

Posted by SawDust on 25 May 2015 - 09:08 PM in Netduino Plus 2 (and Netduino Plus 1)

I am trying to get my Netduino 2+ working with a Sainsmart 2004 I2C LCD (with PCF8574 I2C backpack). I am using Toolbox MultiI2C class, 100KHz clockrate, and 2.2K resistors seem to give nice crisp shape on signal analyzer. The first MultiI2C.Write always produces a NAK, but all succeeding writes produce ACKs. I have checked the analyzer output and it appears the setup commands and write bits are all correct. The good news is that I am seeing some characters, the bad news it they are not the characters I wrote.

 

My test program is writing A, B, C, D … which happens to be the 0100 high nibble column in the ASCII table. However the characters that I see are  … $, 4, D, T, d, t … which happen to be the 0100 low nibble row of the ASCI table. I am writing character high nibble, pulse enable, writing character low nibble, pulse enable... For some reason the last half of the previous character is being combined with the first half of the current character, meaning the LCD interpretation is half a character off (previous low nibble being interpreted as current high nibble, combined with current high nibble being interpreted as current low nibble). Is this shifting a result of the initial NAK? Any ideas on how to get the current high nibble & low nibble back in synch? What is the proper initialization for I2C LCD's, especially with the first NAK?

 

Thanks for any ideas offered on how to solve this problem.

Attached Thumbnails

  • Inital_NAK.png
  • FunctionSet_HighNibble.png

Attached Files



#58582 How to upgrade to the .NET Micro Framework v4.3 SDK

Posted by SawDust on 06 June 2014 - 01:30 AM in Beta Firmware and Drivers

Hello Forum,

I am new to micro controllers and .NET so I am still in the steep slope of the learning curve. I have completed the simple examples and am now experimenting with talking to other devices (that is the point afterall!). I have a serial LCD working and of course solenoids. However I am having trouble with I2C devices so I decided to try the drivers in the MicroFramework Toolbox (thanks Stefan, very nice!), and started with the DS1307 clock example. The toolbox example program crashed immediately and the messages hint at a software version issue (?).

 

I have a Netduino 2 Plus, using the following software:

Visual Studio Express 2012 (v11.0.50727.42)

.NET MicroFramework SDK 4.3 (QFE1) (v4.3.1.0)

Netduino SDK v4.3.1 (Feb 2014) (v4.3.1.0)

.NET MicroFramework Toolbox (v0.1.0.0)

 

I attached a pdf containing a program listing, messages during Deployment, Build, and Debug, and a snapshot of the external references used. I would appreciate any help from an experienced user.

Thanks!

SawDust

Attached File  RTC_test.pdf   176.94KB   7 downloads

 

6/17/2014 Update

I found an answer to my question elsewhere on this forum, downloaded Toolbox compatible with 4.3. Happy camper now with the exception of some Visual Studio 12 stability issues.




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