Newhaven Display Forum

Newhaven Products => Character LCDs => Topic started by: jforest1 on March 18, 2014, 04:48:57 PM

Title: DISPLAY DOES NOT RESOND WITH CORRECT CHARACTER
Post by: jforest1 on March 18, 2014, 04:48:57 PM
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?
Title: Re: DISPLAY DOES NOT RESOND WITH CORRECT CHARACTER
Post by: Michael_L on March 18, 2014, 04:53:04 PM
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.
Title: Re: DISPLAY DOES NOT RESOND WITH CORRECT CHARACTER
Post by: milhead on April 30, 2014, 10:15:00 PM
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