Hello
i have two sets of 5v Arduino Pro mini. i know that using a 3.3v pro mini is better for driving the display, but i am stuck with 2 sets of these components. I don 't mind spending the extra cash if it will save some time, but i am not sure if it will work. I am looking for the easiest turn-key solution. i am also at a beginner level, so please bare with me.
takes 5V as it has a built in voltage regulator, the logic appears to work at 5V,but the TFT will not work at that level.
There is also the issue of the "LED" pin which runs at 3.3V.
issue one:
Could i use a level shifter to solve this issue?
issue two
the LED pin. frankly i don't need to control the brightless level, but the backlight does need to be on, ie i don't care what i connect to it. can the level shifter help?. i have not seen a wire diagram online on how to do this if it is possible.
other options?
in the previous forum post, an E12-82R resistor was suggested to bring down the 5V to 3.3. could that alone work?
I do have a buck converter, if that could somehow help.
Both level shifters can be used. Even if the Sparkfun description is misleading, both are I2C level shifters. I2C means that each channel works in both directions, a low level on either side will result in a low level at the other side. Since your display has SPI interface, you don't need that bidirectional feature. I only mention it in case you cannot identify the input and output pins, mentioned in the Sparkfun description.
I don't recommend current limiting resistors, but a full voltage divider could safely bring a signal down. The buck converter may be required to power the display, but doesn't work as a level shifter.
I have no solution for the LED, couldn't find any description.
so i am okay with using the level shifter for issue 1,
but for issue 2,
why cant i use a current limiting resistor? in the previous arduino post, an E-12-82R was calculated for that specific display. another forum member used a E-12-56R without issues.
the other option
i build a votage divider, wouldnt it just be easier to buck the load LED pin a cheap buck coverter? if that is the case, how would that be connected to the circuit?
For a beginner, it appears that there is some conflicting information, so please help me understand. doesn't the pot only control the current? how can that be used to control the voltage
I bought two items. the first based on your recommendation:,
You are saying you are using a poteniometer.
I purchased a 10k ohm trimpot today. Can this work? also can the ground be shared with the ground from the same ground pin from the 5V stuff, or do i have to use a separate ground on the arduino
and a second using a 3.3 volt voltage divider that handles a 2V drop.
Logic levels. which of the 5 pins (listed below) require a shift?. 3 i know for sure, but the other 2, not so sure.
I learned my lesson the hard way, but necessary way to learn about the arduno. without a doubt the 3.3 volt would have been easier with this display.
But now i have invested quite a bit of time to see it through.
the trimpot has lowered the LED voltage to 3.3,
i bought a logic level converter to lower the logic levels from 5 to 3.3V, but i need a bit of help understanding the pins
From what i understand sck: serial pin- #13: logic needs to change from 5 to 3.3 sda/mosi: serial pin #11: logic needs to change from 5 to 3.3 cs/ss: serial pin #10: logic needs to change from 5 to 3.3
A0: - pro mini pin #9 -- does this need to be shifted using the logic level coverter, is it okay at 5v? Reset: reset - pro mini pin #10 - same question as A0
do these remaining pins need to be adjusted using a logic level contorller? if the answer is yes, i am just going to buy a new 3.3V Pro mini board rather than buying an 8 channel converter.
