To clarify then, the I2C routines of the display's controller are getting into a bad state then if I try to send data to it while it is busy drawing? Or the display sometimes has trouble recieving and buffering data while it is "busy" drawing?

We have used the GLK24064 (without the keypad) for ...

I performed another test as per your post. Here were the conditions:
- All I2C transactions set to 1 byte
- 10 ms delay inserted between each read or write

Bus activity looks like this: start bit, display's address (0x50 or 0x51), writes or reads 1 data byte, stop bit, delay for 10 ms before any ...

Hi Miles,

Thanks for your reply. I'm a little confused by your explaination.

If after a data or address byte was sent to the display, the display were to NACK (ie. it didn't pull the SDA line low for one clock cycle as it would do for an ACK), I can't see how the data line would get pulled low by ...

Hi Miles,

Here's my code for I2C (SMBus). It's for Cygnal's 8051 based C8051F120 that has a built-in hardware I2C controller. In order to simplify debugging, I only ever call the write function with 1 byte of data. The hardware I2C controller generates an interrupt whenever the micro needs to take ...

Hi Tom,

Thanks for the reply.

I tried the 4.7k resistors but it made no difference.

What I have noticed is that the display locks up the I2C bus, holding the data line low forever. When the I2C bus is frozen, if I connect an RS232 cable I can still send commands and data to the display. It's as ...

Tom,

I pulled out the 2k resistors and soldered in some 4.7k ones. Unfortunately, it appears that nothing has changed.

I was experimenting with sending the display some new text strings with command sequences in the middle, and I notice that sometimes an entire command sequence fails to take ...

Hi Tom,

Sure, I'll give the 4.7k resistors a try.

In the meantime, would you be able to provide a little info on how the GLK24064-25 handles I2C communications. Does it use the same 96 byte buffer as it does when using RS232? When it is busy processing a command I send it (such as a font change ...

Hi,

I'm running into problems interfacing a GLK24064-25 LCD to a Cygnal 8051 microcontroller. I've used the micro's built in hardware I2C (SMBus) controller, and I'm able to send text and graphics to the display.

However, I'm experiencing frequent lockups of the display where it will hold the SDA ...