LK204-7T-1U: I2C and voltage levels.
Posted: Tue Apr 20, 2010 7:17 am
Hello Everyone,
My first post. Yes, I'm a newbie, but I did do a search and didn't find anything.
I recently purchased an LK204-7T-1U-GW for use with a Picaxe controller. I plan to use I2C to communicate as I need to use the serial port on the Picaxe for RS485 communication. I was reading the manual for the display, and have this question:
In paragraph 4.1.1, page 17, line 3, it states "The I2C lines operate at 5V normally or 3.3V for -1U style units".
Is the line above a typo? It doesn't make sense to me that a display with a supply voltage of 5V would then drop the I2C voltage to 3.3V. Not to mention that it makes the design difficult as the Picaxe uses 5V and I need to interface with other devices on the I2C lines too. Can anyone confirm that the "3.3V for -1U style units" is a typo and should read "3.3V for -LV style units", the "-LV" being Matrix Orbital's low voltage (3.3V) version of the display?
Thanks,
Arthur
My first post. Yes, I'm a newbie, but I did do a search and didn't find anything.
I recently purchased an LK204-7T-1U-GW for use with a Picaxe controller. I plan to use I2C to communicate as I need to use the serial port on the Picaxe for RS485 communication. I was reading the manual for the display, and have this question:
In paragraph 4.1.1, page 17, line 3, it states "The I2C lines operate at 5V normally or 3.3V for -1U style units".
Is the line above a typo? It doesn't make sense to me that a display with a supply voltage of 5V would then drop the I2C voltage to 3.3V. Not to mention that it makes the design difficult as the Picaxe uses 5V and I need to interface with other devices on the I2C lines too. Can anyone confirm that the "3.3V for -1U style units" is a typo and should read "3.3V for -LV style units", the "-LV" being Matrix Orbital's low voltage (3.3V) version of the display?
Thanks,
Arthur