Hi all ,
I am trying to add a small OLED thermometer on my bike.
I am planning to use this item
Am I worried about the 5v tolerance of the OLED , Is a level shifter needed?
Thank you
Andrea
I put together an Arduino project for my motorbike that controls the grip heaters and additionally reads the time from a RTC module and displays in on a 4 digit OLED display (with an LCD screen, OLED display, and RTC all being connected in parallel on the I2C bus).
I got an adjustable converter and set it to 5V and it's been absolutely fine. I do run it from a 5V Pro Mini though (edit: that's the processor anyway - electrically all are connected to common GND and VCC buses); when I tried to use a Nano the 3.3v outputs weren't high enough to drive the relay that switched the grip heaters without using an optoisolator for level conversion - so I just used the Pro Mini to simplify things.
Does that help?
The term "Nano" is ambiguous these days. Most people think of the classic Nano 3, which is a 5V device. But there are Nano 33, Nano33 BLE, Nano 33 IoT, Nano RP2040 which are 3.3V, and Nano Every, which, like the classic Nano 3, is 5V. Totally confusing!
Yes, you are right.
Which version is better considering I need a small device and that I have to drive an TFT 3-5v?
Should be better use a 3 volts version so I can directly drive the tft with the same power source?
I don't think the answer to the question is clear cut - so I can only speak from my experience which - to date - has been that 3.3v devices have proven to be a PITA (Pain In The A**e) for me - but only from a "triggering a relay" perspective.
I suspect that in reality there are some things that suit only a 3.3v device - some that suit only a 5v device - and a HUGE overlap of projects that suit both.
My personal mantra is to now stick with 5V unless I have a reason otherwise; I just had to make a decision and run with it. 3.3 is probably lower power dissipation but that's not an issue for you. I like the Pro Mini - (all business, no fluff), but you do need an extra cheap bit of kit to program them as they don't come with any kind of USB connection (although I think I've even seen one that does that too).
I use one of these buck converters on an oled as well as other bits in a meter I build here.
Five have been working 24/7 for the last 5 years now without a problem
Note that I don't trust the pot but use the "solderlink" instead.
You should post links to the specs of the devices you already have or intend to purchase and use. As I pointed out, there are many types of "Nano" these days, and there are many types of 0.96" oled.
This is what I got till now.
https://it.aliexpress.com/item/32914468153.html
I bought both 0.96 and 1.3 version
I also get a DS18B20 and a level shifter board just in case
So... not an oled.
If you are going to be successful in any electronics project, you will need to pay more attention to details!
These displays are based on ST7735 (0.96") and ST7789 (1.3") driver chips. Hopefully, the data sheets for those chips will reveal whether level shifters are needed.
What about your "Nano". Do you have that yet? Is it even a Nano?
From the data sheet, we can see that the display is a 3.3V device. 5V would be above its maximum supply voltage:
You are right . I changed my mind versus TFT because I would like to better reproduce the same colors of the stock motorbike strumentation.
I have some Arduino "nano " lying around so I am thinking about using this one .
I am not clear the best way to power supply arduino and tft.
That appears to be a 5v Nano - so assuming your TFT screen is also 5V compatible then all you really need is something like a buck converter to drop your bike's voltage from the 14.7 volts it's probably running at down to 5.0.
These are a "dime a dozen". I'd suggest just getting something that's non adjustable - without a display - but with short-circuit / over-current protection.
My reading of the data sheet (the table I posted above) is that it may not be 5V compatible. The absolute max for the data lines is shown as VDDI+0.3. The most likely output from that regulator on the back of the display is 3.3V, in which case the max would be 3.6V, and 5V from a Nano could damage the display, in theory.
So level shifting might be a good idea for safety. There is no data line from the display back to the Arduino, and even if there was there would probably be no need to use it. So it will only be necessary to level shift the MOSI, CLK, DC lines, from 5V down to 3.3V, and that can be done with a few resistors.
My other concern with the switch from a monochrome OLED to a colour TFT (especially that 1.3" with higher pixel count) is the much higher memory, processing and transfer speed requirements. I suggest you go ahead with building a breadboard prototype with the Nano, but be prepared you might need to upgrade the Nano to get the performance you want.
Thank you very very much for all your help.
I have a level shifter laying around I will need some help connecting all the stuff I 'll post when I'll receive everithing.
Regarding the power needed to drive the tft I hope the nano will be sufficient for at least the 0.96 inch . I only would like to show 2 numbers in slow refresh, temperature, and voltage.
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