I had the wild idea that maybe my little wall wart power supply was too wimpy to power both my development board and the display. (An easy counterpoint to this is that the display works fine with the backlight on over RS232, but I needed something new to try)

I hooked up the display via serial and ...

Bad news...

I tried looping through all the addresses, and only one character gets displayed. So that means 0x5C is the address (which would make sense, since that's what it's jumpered for).

I hooked it up to a scope to look at SCL and SDA. The clock waveform was horrible, (shark fin instead of ...

I think I tried looping the addresses before. 0x5c appears to be the only address that shows anything at all. I know I tried several addresses, but I'm not sure that I looped through them all.

I'll try again this afternoon and let you know.

It's the top left character of the matrix orbital logo on the startup screen.

That link doesn't help very much.

I know all about the addressing. The addressing in the mega16 works similarly. It interprets the adddress as an 8-bit number, with the high 7 bits being the actual address, and the LSB as read/write.

The only question would be if 0x5c is the 'matrix orbital ...

I'm having trouble getting I2C to work with my LK204-25, rev1.23 and an Atmel ATmega16 microcontroller.

The mega16 has built-in I2C (although they call it two-wire interface), so I'm using that facility with the sample code from the mega16 manual.

My test program just writes a start bit, the ...

for that header, voltages are as follows:
PIN : VOLTAGE
===========
1: GND
2: 5.0 V
3: 3.3 V
4: 3.0 V
5: 3.2 V
6: 3.0 V
7: 3.1 V
8: 3.1 V
9: 3.3 V
10: 3.1 V
11: 3.4 V
12: 3.4 V
13: 3.4 V
14: 3.5 V
15: 5.0 V
16: 3.0 V

input voltage is 5.05 V, steady.

also, total current to the display starts at 55 mA when you power it up, but slowly drops to about 52 mA.

So something's using current...

Sure, I've got a multimeter. What do I need to check?

I recently purchased an LK204-25WB, and am quite pleased with it. However, after playing with it successfully a few times, it suddenly and inexplicably doesn't work. I can't even get it to power up. I've made all the proper connections, and have a power supply with proper voltage and sufficient ...