I am trying to substitute a DUE in place of a Mega 2560. I am powering devices (Adafruit GPS, Adafruit SD Breakout board, and an lcd screen with the 5 volt output. Can I simply change to the 3.3 volt output and expect these devices to still work?
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Thanks for the advice. Brain is working and the question is answered, but I still have a question. The instructions for using the DUE say that one cannot power sensors or devices with the same 5 V that the other Arduino boards use. My LCD screen must have 5 Volts to power it. The Due has a 5 volt output right next to the 3.3 V output. Why is it there if it cannot be used or is it OK to use to power the LCD ?
You misunderstood those words about the Due. You can use its 5V output to power other devices but you can not connect the 5V signals from the 5V device to the Due without the appropriate signal level shifters. Any input to the Due over 3V3 will kill it. Any 3V3 output from the Due will not be enough to reliably signal an input to a 5V device.
Also the current output from a Due’s output is very limited compared to an Arduino, there are some pins that can only output about 3mA, check which pins you are using.
Grumpy_Mike:
Any 3V3 output from the Due will not be enough to reliably signal an input to a 5V device.
Practically, the 3.3V logic signals of Arduino DUE well-reliably drive the input lines of the 5V standard LCD. It happens so due to VIH value of LCD (2.2V) which is less than 3.3V (the VOH of DUE).
Edit: Top figure is cancelled in view of Post#5.
As a general piece of advice 3V3 is not always sufficient to drive 5V logic levels, which are normally 0.7Vcc, there are some chips that are an exception to this, mainly those designed to run off a lower voltage.
It is obvious that the data sheet you found for the LCD is not a 5V device and therefore my advice of:-
Any 3V3 output from the Due will not be enough to reliably signal an input to a 5V device.
is solid.
As you say:-
the input lines of the 5V standard LCD.
That data sheet is not for a 5V standard LCD it is for a 3V LCD.
And so your advice, as usual, is very suspect and in truth not very good.
Grumpy_Mike:
As a general piece of advice 3V3 is not always sufficient to drive 5V logic levels, which are normally 0.7Vcc, there are some chips that are an exception to this, mainly those designed to run off a lower voltage.It is obvious that the data sheet you found for the LCD is not a 5V device and therefore my advice of:-
is solid.As you say:-That data sheet is not for a 5V standard LCD it is for a 3V LCD.
And so your advice, as usual, is very suspect and in truth not very good.
The following Tables support that both 3.3V LCD and 5V LCD will be well-reliably driven by DUE as the VIH (2.2V) of both LCDs are lower than VOH (3.3V) of DUE.
**BTW:**Opinion should be supported by documentary evidence.
Opinion should be supported by documentary evidence.
Random unattributed snippets of data sheets are not documentary evidence. Where do those things come from?
The only thing the OP said was:-
an lcd screen with the 5 volt output.
Given that an LCD screen doesn’t have an output only inputs you can’t assume what he has at all, let alone then go and look up some random data sheet of something that he might have.
Your answers are rubbish it would be better if you didn’t bother.
Grumpy_Mike:
Random unattributed snippets of data sheets are not documentary evidence. Where do those things come from?
1. This is the data sheets for 3.3V LCD.
2. This is the data sheets for 5V LCD.
Please, hook up a 5V LCD with DUE and observe that it works and proudly disproves your proposition -- Any 3V3 output from the Due will not be enough to reliably signal an input to a 5V device.
Grumpy_Mike:
Your answers are rubbish it would be better if you didn’t bother.
Please be kind to bear in mind that there are some Members in this Forum who are non-native, and they extract the meaning of a written expression looking at the well established punctuation marks/rules of the English Language. While there are clearly two independent sentences/clauses in your above quoted sentence, you (as a veteran) have not used punctuation mark (the semicolon) to join them together and thus have made the reader's life difficult to conceive the meaning of the whole sentence.
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GolamMostafa:
1. This is the data sheets for 3.3V LCD.
2. This is the data sheets for 5V LCD.
That might well be the data sheet for one particular LCD, but I dont recall the OP said which LCD or LCD controller they were using ?
spycatcher2k:
GolamMostafa starts talking rubbish AGAIN!
A Rubbish saying can only be oppressed by ANOTHER Rubbish saying?