Display does not respond with correct character

jforest1

• March 18, 2014 10:07

I have a hnd-0420d3z-nsw-bbw-v3 using in spi mode -- clock at about 96khz

sending an oxfe displays graphics character for oxfd, sending ox58 displays a "-".

there seems to be no way to send a control function because the 0xfe is not interpreted correctly.

on the scope it seems that the correct data is sent.

the mcu works great with bosch accelerometer parts.

any suggestions?

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  Michael_L

  • March 18, 2014 11:07

  It seems you are experiencing a timing issue.  Can you try slowing down the SPI to see if you get the correct characters?
  Also please be aware of the execution times shown on page 7 of the datasheet.

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  milhead

  • March 30, 2014 11:07

  JForest,
  
  While messing around to get my display to work I encountered the exact same problem.  Check your SPI protocol and make sure that it us operating in SPI Mode 3, CPOL=1, and CPHA=1.   (http://en.wikipedia.org/wiki/Serial_Peripheral_Interface_Bus)  Also make sure that all transfers are a single byte (while !CS is low).
  
  I am reliably writing to my display (same as yours) and while fooling with my SPI transfer code saw the exact same failures that you saw.
  
  I'm running my transfer clock at 85Khz but am careful to allow the processing time for each command as outlined in the data sheet.
  
  Miller

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