MCUFRIEND 480x320 Compatibility Question

I think some are saying the ili9488 320x480 LCD's can run on a 5v UNO, some say no. I have never seen the 74HC series I/O chips run with logic levels 1.7 volts higher than VCC. This series though is a DP74HC245. I could not find a detailed data sheet that says if it can or can't.

Also I could not find the max bit rate for the FET based level converters. Some converters are as low as 0.9 Mega bits/second and some up to 100 Mbs. Slow logic levels may be giving people a problem.

I haven't attempted to wire mine up yet. Probably should just get a DUE for the LCD's.

Last question, is there a library to use the display as an ASCII terminal, such as VT100. Would be nice to have a choice between USB or serial input, to use on other Arduino projects.

There are two styles of Mcufriend Shields. Uno shields and Mega shields. The difference is pretty obvious. The Mega shields have more pins.

The Uno shields will fit on a Uno or a Mega. They use '245 buffer chips for converting the logic levels to 3.3V for the display controller chip.

Most seem to have regular 74HC245 chips instead of 74VHC245 chips.

In practice this means that there is a certain amount of backfeeding power from the Arduino's 5V logic levels when HC parts are used. The VHC parts are designed to be tolerant of inputs greater than VCC.

In real life, the Uno shields work just fine with 5V Uno, Mega or with 3.3V Due, Zero boards. The Uno shields can read and write to controller memory. The Uno shields work fine with the microSD but rely on the microSD being tolerant. The Uno shields have a simple resistive Touchscreen that shares the TFT pins. It works fine on Uno, Mega. Not so well on Due, Zero.

The Mega shields use resistors for level conversion instead of '245 chips. The Mega shields can NOT read memory. The Mega shields are unreliable with the microSD because the resistors are too high. The Mega shields have an intelligent XPT2046 Touch controller chip which works fine.

David.

Thanks for the help. Some are saying they can run it on a 3.3v UNO but not 5 volt. I would think it's going to be very slow with a 8 mhz. Some 3.3v UNO's use a 12 mhz USB chip clock. Later I will see if I can tap that 12mhz, take the resonator off the MCU and inject the 12mhz.

Else I search for 12 mhz resonators.

Thanks for the help. It has been running for over 45 minutes on a 5 volt Pro Mini. I could not find any Vin max listed in the 74HC data sheets, they appear as the 74LV. Also found talk of it being ok on other sites. 74HCT is supposedly not useable for this since it apparently for TTL levels.

Now about that 3.3v regulator on the display board. It would be nice to tap into it for the 3.3 volt logic supply. It is only slightly warm so I will try to see if it can also power the display board logic and SD card. I do not know why it currently needs 3.3v from the Arduino.