VFD2041 I2C woes

adidafag · Post by **adidafag** » Wed Mar 29, 2006 11:35 am

I am trying to interface a VFD2041 Rev 1.4 display to an Atmega16 microcontroller. I followed the instructions in the Atmega16 datasheet for I2C communication, and attempted to transmit data to the display. The display does not acknowledge its I2C address. Jumpers J1 and J2 are set, so according to the VFD2041 datasheet its address is 0x5C, which makes its write address 0xB8. I 'scoped the SCL and SDA lines, and the SDA line is definitely high during the ACK cycle. Please help.

Thank you.

Raquel · Post by **Raquel** » Wed Mar 29, 2006 12:28 pm

Hi adidafag,

Matrix Orbital implements a little different I2C slave addressing. When you set the jumpers for 0x5C, the write address is 0x5C and the read address is 0x5D.

Please try this address and let me know how it turns out.

adidafag · Post by **adidafag** » Wed Mar 29, 2006 1:58 pm

I tried addressing the VFD2041 with 0x5C, but I still did not receive an acknowledge from the module.

Any other suggestions?

Raquel · Post by **Raquel** » Wed Mar 29, 2006 2:22 pm

Hi adidafag,

I wonder about the PCB revision of your VFD2041 (I think 1.4 is the firmware rev), it should be printed on the board. I wonder if you already changed the board to communicate via I2C.

adidafag · Post by **adidafag** » Wed Mar 29, 2006 3:22 pm

The module says VFD2041 REV1.4 on it. I don't see any PCB revision number. How do I modify it to establish I2C?

Raquel · Post by **Raquel** » Thu Mar 30, 2006 7:25 am

Hi adidafag,

I was looking for a VFD2041 that does not say the PCB revision on it, and I can't seem to find one, so your board must be really old. Do you mind posting a picture of it so that I may be able to see what you have? Thanks.

Jon · Post by **Jon** » Tue Apr 04, 2006 3:00 pm

I could be wrong, but if you haven't changed the address the default should be 0x50 for write, and 0x51 for read?

VFD2041 I2C woes

VFD2041 I2C woes

0x5c address did not help...