TFT Display with atmega32

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#1
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Hello Every one;

                       I have a display which have controller ILI2935. I want to use it with atmega32 using SPI. I tried getting some information but I am not able to get it. Kindly help me out.

 

   

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Have you looked at the Arduino drivers for this display?

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Thanks For reply. Actully I don't have idea how to use (possible or not) Arduino drivers for Atmega32, so I didn't tried much for Arduino drivers.

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I just want to use display not touch pad.

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No, that shield uses the parallel 8080-8 interface. It is not possible to use SPI for the TFT.
.
It does use SPI for the microSD
.
The shield is designed to plug into an Arduino. It might contain ANY controller. It is unlikely to contain ILI9325 but it might.

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Ok. As I am getting you are saying that this display will not run on SPI Protocol??

 

Kindly suggest me the parallel communication material for this display.

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I Googled mega32 arduino........

 

http://www.instructables.com/id/...

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I checked the link.

I have google and got to know that lcd model number is ST7781, is there any material available which tell me all the connections. I am confuse.

Last Edited: Tue. May 15, 2018 - 07:11 AM
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Abhay02 wrote:
is there any material available which tell me all the connections

That should be available from wherever you bought the thing.

 

As it is an Arduino shield, you should also be able to find Arduino examples to go with it.

 

You should start by getting it to work with an Arduino. Then, once you have a working point-of-reference, you can (if you still want to) move on to porting it to some other target.

 

It would be easier to just set this aside (at least for now) and get a display which does come with a suitable level of support...

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Life is much simpler if you just buy an Arduino Uno clone.    Plug the Shield in.   Install MCUFRIEND_kbv library via the IDE Library Manager.

 

Yes,   you can run the shield with a mega32.   But first you have to provide a 3.3V reference voltage to the 3.3V pin on the shield.

And it requires quite a lot of work to write the software.

 

If you really want to do this,   provide a schematic and photo of your hardware.    I can probably provide an AS7 project in C or C++.

 

David.

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These are my hardware..LCD  is ST7781 and Controller is ATMEGA32. 

Last Edited: Tue. May 15, 2018 - 07:52 AM
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"I have google and got to know that lcd model number is ST7781, is there any material available which tell me all the connections. I am confuse."

This is ambiguous :

Do you answer to Kartman's post 7 or do you negate the title and your 1rst sentence at post 1?

 

You first should test it on an arduino :

some arduino  libraries can detect the type of the display (it is often stored in an EEPROM, I am afraid it is .. the empty -illustrating Murphys law-  placeholder (2x4)  in the red photo; else, they scan for each kind of display ... they know). Perhaps an IT link to the place where you bought would be useful?

 

You should tell what is written on the 2 existing ICs on the red photo (one cannot guess them whithout telescopic eyes)

Bettere than posting the other side of the green M32 photo, you should take a photo of its schematics (even if hand made : it is much easier than putting togeteher boths sides of a rather dense PCB)

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I am very familiar with these Mcufriend Uno Shields.    They require a 3.3V reference voltage.   

 

If you are prepared to make an effort,   I am happy to help you.

If not,   I will not waste my time.

 

David.

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Yes I want to do this kindly tell me the circuit.

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It is your job to make the hardware.

You require GND, 5V, 3V3.

You require LCD_RD to LCD_RST control lines

You require LCD_D0 to LCD_D7 data lines

A total of 16 wires.

 

I will do nothing until you show that you can wire up the hardware.  i.e. schematic and photo.

 

The Shield has level shifters.   It will work with 3.3V or 5V logic levels.

 

David.

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You should really post a schematic of your MCU card (the green one on the right) or an IT link to it.. to know which lines are already used (one does not have crystal balls)

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With 2.4" TFT shields like this one, you never know what the TFT controller is inside AND you will destroy the unit attempting to open it.  The only thing that you can do is send parallel 8-bit bytes to it and try to make sense out of anything that you able to read back.  This family of 2.4" TFT controller shields have no documentation, and they have many different internal designs and configurations, and you can't tell how to get it working from looking at it

 

Unfortunately for you, it is doubtful that anyone in the world has been able to make this UNO-shield parallel-interface 2.4" TFT work with an AVR Mega32.  You need to be a video engineer (to understand the TFT data sheets), an expert C programmer, and an AVR expert.  All of which you are not.

 

Fortunately for you, Mr. Prentice, one of the world's experts at UNO-shield parallel-interface 2.4" TFTs, has offered to help you.

 

The first thing to do is get the TFT working, then get the touch-screen working.   The touch screen uses two ADC channels and two I/O pins (that are shared with the TFT parallel-bus).  You have to know what these four pins are.  They will be different on identically-looking shields, and, the board manufacturer/seller can offer you none of the documentation that you need to get it working.

 

Forget about using the Mega32.  This board and all of its downloadable libraries is meant to work with an Arduino UNO which has an internal Mega328P CPU.  In theory, the Mega32 and Mega328P are nearly identical internally.  But the working libraries for this controller are written using the Arduino extended keywords of C++.  You will go crazy trying to convert Arduino Mega328P C++ into AVR Mega32 C code.  If you can't buy a Chinese clone of an Arduino UNO for $5 on eBay, then you need to move to a country that allows you to do so if you are going to be a professional embedded-systems AVR developer in the modern world.

 

I have had good luck with one of these 2.4" TFT ST7781 units by using the UNO library provided by SmokeAndWires.co.nz.   Mr Prentice's tool, MCUFRIEND, may recognize your unit.  I've bought about ten parallel 2.4" TFT shields from eBay over the past four years, and MCUFRIEND has recognized seven of them.  Not bad for exploring undocumented Chinese techno eBay dump units.

 

The two big surface-mount ICs on the back of the red board are 74HC245 level shifters that convert the Arduino +5V signals to the +3.3V used by the TFT.  The 2x4 IC pads (with no IC) is for a Serial RAM IC that uses the same SPI signals as the SD card (with different CS lines).  The TFT itself does not use SPI interfacing.

Last Edited: Wed. May 16, 2018 - 01:40 AM
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I've bought about ten parallel 2.4" TFT shields from eBay over the past four years, and MCUFRIEND has recognized seven of them. 

Go on.   What is the readreg report  for the the three unknown ones?

Or did you try to dismantle them yourself?

 

I would expect at least nine out of ten to work.

 

David.

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Hi David;

    It is done with ATMEGA32.

 

LCD_RST  =>   PD0

LCD_RD  =>    PD1

 

LCD_D0   =>  PA0   

LCD_D1  =>   PA1  

LCD_D2  =>   PA2   

LCD_D3  =>   PA3   

LCD_D4  =>   PA4   

LCD_D5  =>   PA5   

LCD_D6  =>   PA6   

LCD_D7  =>   PA7

 

 

 

   

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What about LCD_WR, RS, CS ?
Where does the 3.3V come from?
.
Seriously, your previous thresds went on for days and weeks. I am not going to waste my time.
If you take 20 minutes from your life to provide proper schematic and photo, you will get sensible replies.
.
David.

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Simonetta wrote:
You will go crazy trying to convert Arduino Mega328P C++ into AVR Mega32 C code.

 

Would installing Mighty Core into the Arduino IDE to add M32 to the list of supported chips help? 

Then the OP could load/run the sketches for the display. 

 

Jim

Click Link: Get Free Stock: Retire early!

share.robinhood.com/jamesc3274

 

 

 

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The software side is fairly trivial.

 

Getting the OP to provide proper hardware and information is another matter.

 

David.

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Hi David,

Is it ok??

I will provide two different power sources of 5V and 3.3 Volts.

Now, kindly tell me these connections are ok or not??

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Abhay02 wrote:
I will provide two different power sources of 5V and 3.3 Volts.

So show that on your schematic, then.

 

Your schematic should be a complete description of all your connections!

 

Seriously:  a schematic is a far more efficient way to describe a circuit than trying to write it all in words - as David keeps telling you!

 

It is also not subject to language barrier problems.

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Excuse me, but is there a 5-> 3.3v shipped with this shield? (this happens with some shields, to make life more comfortable).

In this case, there remains "only" one wire to show (and supplies are often on ... different schemas, to make reading easier: a supply less schema is read more efficiently).

A trivial one, out of 14 non trivial....

 

Else, wiring a LDO and 3 decoupling capacitors is straightforward (but a photo might show it was not forgotten). In this unpleasant case, remain two trivial wires out of 14.... which should not be put into the same schema to keep some efficiency in reading

 

Oh, btw : a list of connections as you did is easier to keep as part of commentaries -no mechanical invocation of "language barrier"  (I bet you comment your softwares...), and some colors cannot be seen if one of yourreaders  is color blind -even google serach can explain it!- : a list of connections is therefore .... more efficient, on the long term (except for analog circuitry, where schematics are necessay : digital cards are another issue, which should not be transposed mechanically).

 

 

BTW :I warrant you D. Prentice was not trying to belittle you nor showing a google superiority (he is well known in adapting Arduino to dozens of  weird cicruits and screens)  when wanting all control and data signals to be known before attempting to give you some software....

Last Edited: Thu. May 17, 2018 - 08:09 AM
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Most Mcufriend pcbs have two 74HC245 buffers and one AMS1117 3.3V regulator.

The AMS1117 provides 3.3V to the backlight LEDs via a current limiting resistor.  

It does not provide a reference for the 74HC245.    The 74HC245 uses the 3V3 pin from the Arduino as 3.3V reference.

 

The photo in #1 does not show any LDO regulator.    It looks as if Mcufriend is saving components.    I assume that the backlight is fed from 5V via a (larger) limit resistor.     And the 74HC245 buffers still use the external 3V3 pin.

 

Ebay and AliExpress vendors often publish photos that do not represent what they are selling.    And they certainly publish inaccurate technical details.

It looks as if the photo in #1 is the actual display on the OP's real desk.

 

Yes,  it would be quite easy for the OP to add the 3.3V regulator to the schematic.   The rest of the schematic is fine.

And I would like to see the actual wiring in a clear photo that can be compared to the schematic.

 

Once I see the proper hardware connections I will attach an AS7 project for you.    Do you want C or C++ ?

 

Life is much simpler with a £3 Uno clone.    You just plug the Shield into the Arduino header sockets.

 

David. 

Last Edited: Thu. May 17, 2018 - 09:05 AM
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"Life is much simpler with a £3 Uno clone.    You just plug the Shield into the Arduino header sockets."

Well, life of these xxx friends can be less complicated with reliable connections (are dupont wires reliable).

But, as I read, one year ago, about these cheap graphic screens, I was terrified (one can find out which driver exists by trial and ** many** errors from their IT site) and cowardly decided not to buy.

Simonetta, who is much more competent than I am, had 70% of these screens working -thus, 30% were desesperating- , and you have more than 90% (this thread)...

 

I am afraid OP should post 4 photos (edited : or make a PCB to give som compatibility whith his card and arduino, if he intends to test many arduino shields, if he is rich and if he has skills in PCB drawing) :

 

one of his extra 3.3v supply.

one of the connections Dupont wires <-> screen // or swear he checked it somehow...

another of the connections Dupont wires <-> his card // ""

last one, where wires can be followed, to show the connections card <-> screen (the one he posted is too small and wires cannot be followed by eye - some jumped out of the photo-)

There is nothing more unpleasant than looking for loose connections (and odds of miswiring -16 flying wires- are very high in this context), or, worse, trying to adapt software as there is a trivial HW issue.

Last Edited: Thu. May 17, 2018 - 09:49 AM
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Thanks for reply David.

I am comfortable with C language.

I can provide 5 volt from my board which I am using the blue one (As in POST#19) and I am providing 3.3 volt from a different power source is it ok??

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Or use a LDO (advantages if you turn off your M32 card, shield will be turned off, too : I bet there remain enough milliamps; other advantage : you will mimic an arduino HW, shield is meant for) and two decoupling capacitors.

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@dbrion0606,

 

You can read the controller ID from the Mcufriend Uno Shields.

The Mcufriend Mega2560 Shields are write-only.    Hence guesswork.

 

I have probably got 100% of displays working if I get them on my desk.

 

I have got several running with a remote owner/user.

 

It can be quite a struggle if I can't get a datasheet.

 

@Abhay02,

 

I would be happier to see 3.3V from an LDO powered by your single 5V supply.

Then I know that everything is safe when you remove 5V power.

 

David.

Last Edited: Thu. May 17, 2018 - 10:28 AM
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"You can read the controller ID from the Mcufriend Uno Shields."

Is the controller id stored into the controller (Simonetta hinted it) or into an EEPROM (it was a wild bet of mine, very unlikely, as they seem not to add extra circuits -even a 5v -3v converter-)?

 

 

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The silicon contains an ID register.    You read the register to identify which controller chip is mounted.    Note that the silicon is not normally in a human viewable package.

 

Many displays do not make the RD pin accessible.    So this type of display requires a well polished crystal ball.

 

The silicon often contains some EEPROM cells to store manufacturer configuration data.    They are normally OTP, write-twice or write-thrice.

I have only ever come across one controller that lets you write to EEPROM with regular supply voltage (and multiple times).

 

David.

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Hi David;

             Here is my circuit this is same as post #23 circuit diagram. I have just used a separate circuit (Small Blue board) to provide 3.3 volt. The grounds of both circuit boards (The small blue board and the main bigger board) are connected.

Please guide me further.

Last Edited: Mon. May 21, 2018 - 08:40 AM
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Well, I do not see wheteher

a) your small blue beard converts 5v (from the M32 board) into 3.3

or

b) whether is is a main <->3.3v adapter.

 

D. Prentice wrote, in post 30 :

"would be happier to see 3.3V from an LDO powered by your single 5V supply.

Then I know that everything is safe when you remove 5V power.

"

Solution a) M32 beard -> 5v blue board -> 3.3 -> TFT supply is felt safe....

 

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For now it is not possible for me to provide 3.3 v from LDO powered, beacuse this board is designed for a specific task.. Please guide me further.. after these connections what I need to do..

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Well, I see  many ugly solutions for this supply issue :

 

a) buy an Arduino (maybe it is the cheapest solution and fastest one : it seems the easiest way to know wheteher your TFT is working...)

 

b) -temporarily- remove the regulator inside your card; replace it by a more powerful one which can feed LDO+screen.

Perhaps adding an heathshield / fan? would be enough, if 5v is avalaible...

 

c) keep things as they are, with a risk of damaging your screen (at least, *244) if it powered off before the MCU board . This a risk, not certain.

 

d) if you have other M32, try with another board and more powerful supply...

 

I bet there are others...

 

BTW your wiring seems much  better than in the 1rst photo.

 

 

 

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I need to do it with atmega32 only, I can't use other boards. If you can help me out then help me.

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I don't have any issue in case my tft is damage I just want it in working condition as soon as possible. So please suggest me the code.

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Well, I have no idea of the code (looked at D PRentice github : he made a huge work  for dozens of screens (it is very well writtne , but it is ... hundreds of lines) : as I am very curious of how these TFT screens work (my curiosity and my ignorance could be deduced from the questions I asked ... in this very thread) , I tried to fix all the secondary issues (edited : I felt that solving these  these issues was a necessary condition)  to be almost sure all/most of  the ugly  details could not compromise the very subject of your interesting topic....

Last Edited: Wed. May 23, 2018 - 05:23 PM
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A TFT display is fairly straightforward.

1.   configure some registers as a one-off initialisation in setup()

2.   specify a rectangular window area.

3.   write pixel(s) to that area.

4.   back to (2)

 

Drawing a single pixel just needs a 1 pixel window.

Drawing a filled rectangle means (2) followed by W x H pixels either same colour or different e.g. from a photo.

A horizontal or vertical line is just a "thin" rectangle.

Drawing a letter from a font is filling the rectangle with pixels from the letter's bitmap

 

If your TFT is in Portrait mode with a known controller on a known target,   the functions are small.

My "library" looks complex because it caters for 40 odd controllers on multiple targets with multiple wiring schemes.

Strip it down to single ILI9320 on an ATmega32 and it is manageable.

 

I really do not understand why he can not buy a Uno clone and plug in the Shield.    100% reliable wiring.   100% reliable Arduino library code.

 

I am still waiting for Abhay02 to produce some wiring that "looks" reliable.    And an explanation "why mega32?"

 

Arduino libraries use C++ and inherit from existing classes.

You can use the same Print.h methods on Serial, LCD, GLCD, OLED, TFT, ...

You can use the same Adafruit_GFX.h methods on GLCD, OLED, TFT, ...

 

Converting C++ code back to C code is a bit messy.

Existing GFX methods for drawing lines, circles, text, ... add up to a LOT of C++ methods or C functions.

 

David.

Last Edited: Thu. May 24, 2018 - 09:45 AM
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I am not using any other board because I am working on a project which is already completed, but now I wanted to change the display. That's why I can't use any other board.

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Is there any program available on the internet though which I can make my program because I am new in tft display and have a very short period of time.

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have a very short period of time.

 

Stop your watch (sell it) , tear off / sell  your calendars. (nobody here , except you, negociated for delays)

 

I am very new in tft displays (and interested in this matter); google search brought me back mcufriend and mcufriendkbv (in is a keyword which was given **you**, in this very thread .... a week ago (unless I am in a temporal singularity).

 

It took days to know how you wire together cards : this knowledge  is necessary to protect both cards against hardware failures, and to program, too (do you believe the same program will work if you change, say, data line connections? It is not a matter of neing new to any kind of hardware, it is just a matter of common sense).

I was very annoyed with the power supply connection, and could not find satisfying answers (maybe it is just a matter of ... adding a heathsink : with the utterly deficient info you gave, it takes days to solve a very trivial issue.... How do you expect more complicated issues to be solved, with the way you "work")

 

Let us go back to IT adresses : most are unreliable (posting in a blog one tried a tft, and wait for readers to correct it leads to google hits...)

 

THE bets I found was D. Prentice github:  (it would take me 6 hours to understand 1000 lines of well written C++ code ; my brain is slow and mcufriend_kbv is more than 3000 lines); code is meant for arduini, and D Prentice (I know, from his contributions in the MCU world, he never (at least, I never detected) makes mistakes)   was kind enough to offer you to adapt it to C and to the specificities of you card. Conditions were : your HW is in a satisfactory state (for me, it improved; is it enough? it is a necessary condition); else, it would be a waste of time for him (for you, it would be a waste of time ... and money).

 

He was kind enough, too,  to remove some bad ideas of mine (before I buy TFTs).

 

If you add delays one never heard of (and one never should have heard of), what do you think will occur when someone, who freely (btw : did you sell this TFT idea? did you tell you were new?) and with great talents writes good quality software (he needs time, too, to read docs,  and do other things he likes) will think? 

Last Edited: Fri. May 25, 2018 - 10:06 AM
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Dear Mam;

                If you can help me out then please help me out, unless kindly don't comment irrelevantly.

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Abhay02 wrote:
That's why I can't use any other board.

That does not mean that you can't use another board to learn on.

 

Then, when you have gained sufficient experience to know what you're doing, you can apply that to your existing board.

 

 

EDIT

 

See #9 !

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Last Edited: Fri. May 25, 2018 - 10:14 AM
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Abhay02 wrote:
I am new in tft display and have a very short period of time

All the more reason to ensure that the display you select comes with complete documentation and full support! 

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Then, when you have gained sufficient experience to know what you're doing, you can apply that to your existing board.

 

I would add

and sell software and talent (when people unexpectedly speak about delays, and get very nervous : sounds like someone sold software and talents without reading any doc -from answers to trivial questions-)

BTW : knowing what one is doing is not necessary : knowing what other people are doing might be enough (one often relies on HW manufacturers) 

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Abhay02 wrote:

I am not using any other board because I am working on a project which is already completed, but now I wanted to change the display. That's why I can't use any other board.

We are not telling you to use another board...we are saying to buy a cheap arduino and run the software given by Mr Prentice.. then you will know what type of display it is and the library required to run it. Then you can use this info to make the display work with your mega 32. It's been over a week if you would have spent the $10 For an arduino clone you probably could have had this project up and running.

You would also have the required hardware to test any display in the future.

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Ok tell me the code for arduino.

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david.prentice wrote:
Life is much simpler if you just buy an Arduino Uno clone. Plug the Shield in. Install MCUFRIEND_kbv library via the IDE Library Manager. Yes, you can run the shield with a mega32. But first you have to provide a 3.3V reference voltage to the 3.3V pin on the shield. And it requires quite a lot of work to write the software. If you really want to do this, provide a schematic and photo of your hardware. I can probably provide an AS7 project in C or C++. David.

This was message #10 in a LONG thread.

 

Buy or borrow the Uno.   The library will identify the actual controller.  #1 says ILI9325.  #11 says ST7781.   You do not seem to know.    It is unlikely to be either,  but both types were common 4 or 5 years ago.

 

Yes,   MCUFRIEND_kbv is fairly big and complex because it supports many controllers.    If I know which controller,  I can strip the code down to just support one controller on one target e.g. ATmega32.    But it still needs a reliable 3.3V reference.

 

David.

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  But it still needs a reliable 3.3V reference.

 

Well,  7805 -> 3.3v LDO (have many names) are reliable (mimic Arduino power supply, IIRC) .

 

If one knew the name of M32 board regulator (from photo, has the same ... size... as a 7805; this name cannot be deduced from photo, but either from schematics (at least bill of materials) or from close inspection : noone on the wild wild web has telescopic eyes, except Mr OP....

one could know whether :

it is just a  very trivial : takes minutes, instead of days of begging for common sense info -hardware is not a matter of industrial spying....; hiding this info seems irrational- matter of

         adding an heathsink (if regulated 5v is avalaible through connector; 7805 are overkill for M32) , the 3 pins + 2 capacitors LDO....

or

it is more complicated (and to which extend). (the preexisting 7805 is likely, but bets are often silly....

 

Advantages of getting 3.v from otherboard (with  MCU ) : there is no risk of seeing a card being fed, while the other is not (can damage circuits )....

 

 

BTW : as Arduino peripherals, ready to be plugged in,  are very popular, having a card that interfaces an old card with arduino shields (and offers 3.v supply , perhaps even 3.3v <->5v level shifting) would be usefull on the middle term (RPi already have...)

 

 

 

 

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