NHD-0420D3Z-FL-GBW-3V Dropping characters over I2c

camac881

• November 11, 2014 09:07

Hello All,
 I saw the other posts about losing characters over I2c due to firmware issues and tried the same fix by slowing it down. It has gotten better but I'm still dropping the occasional character. I am running the screen from an Arduino Uno and displaying data from an SPI A/D converter.

My question is what is the correct way to code a speed correction for the Arduino? The line I'm using now is #define TWI_FREQ = 100000L / 6; Is that correct?

Thanks,
Cam

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  Michael_L

  • November 11, 2014 10:07

  I'm not sure if this applies to the Uno as well as the Mega, but with the Arduino Mega I have used "TWBR = 152;" (sets I2C clock frequency to 50kHz) after I call "Wire.begin()" in the setup() function.
  I would check the Arduino forums/documentation to confirm this works with the Uno too.

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  camac881

  • November 12, 2014 10:07

  Hello Michael,

  That worked perfectly. Thank you.
  
  I checked the Wire library reference at Arduino.cc and they referenced the data sheet at Atmel and a table that does not make this any clearer. How do you come up with the number? Do you gather all the pieces and run them through the formula? It seems like herding cats to me.
  
  Thanks for your help!
  Cam

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  Michael_L

  • November 13, 2014 10:07

  You're welcome!  This site should help:
  
  http://www.gammon.com.au/forum/?id=10896

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