Newhaven Display Forum

Newhaven Products => Character LCDs => Topic started by: SaintGimp on April 05, 2014, 04:41:06 PM

Title: NHD-0216K3Z-FL-GBW-V3 losing/dropping characters
Post by: SaintGimp on April 05, 2014, 04:41:06 PM
I'm testing a NHD-0216K3Z-FL-GBW-V3 with I2C communication and am having problems with the display randomly losing or dropping characters.  I'm running the I2C bus at ~90K data rate and the display is the only device other than the master on the bus.  At this data rate the display will sometimes randomly lose a character, as though it were never sent.  This seems to happen more frequently when several characters are sent in a single transmission but also happens even when transmitting one character at a time.

The I2C bus signals look fine on a scope with nice square waves, and the display correctly ACKs every byte with no errors, but occasionally a character that was correctly ACKed simply doesn't make it to the screen.

I've seen several other people mentioning this problem on various web forums but haven't seen any good explanation for why this is happening.  I found through trial and error that if I cut the data transmission rate in half (to ~45K) the problem largely (entirely?) disappears, but as noted above this doesn't appear to be an I2C bus problem.

Has anyone else seen this problem and are there any better solutions?
Title: Re: NHD-0216K3Z-FL-GBW-V3 losing/dropping characters
Post by: Michael_L on April 07, 2014, 08:57:01 AM
We are seeing some of our customers having this problem, and is usually "fixed" by lowering the I2C bus speed to ~60KHz or less.  This is an issue with the current firmware on the display and not the display's components themselves.  We are currently working on a firmware revision to correct this timing issue, and we greatly apologize for any inconveniences caused.