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Fixed V1.0 version of SainSmart TFT LCD Adjustable Shield for Arduino Mega 2560
  • Hello All

    Like others I found out that the SD interface on the TFT LCD didn't work when connected with the 1.0 version of the LCD shield. I contacted SainsSmart and never did get a reply. I then did a bunch of Google searches and came up with very little so I re-engineered the thing myself and got the SD card interface to work flawlessly even at high speed. The problem is the circuit board's layout is in error. Why SainSmart didn't test this functionality before selling us this board is anyone's guess.

    Anyway, it is important to understand the correct connections needed to make to the SD interface work.

    MEGA 2560 ------ LCD PCB Connector
    MISO pin 50 ------------ 35
    SCK pin 52 ------------ 36
    MOSI pin 51 ------------ 37
    CS pin 53 ------------ 38

    Check out the image at: http://www.craigandheather.net/misc/MegaShield.png

    The area in the red square is the area we are interested in. It shows the four surface mount resistors and I've labeled each side of the resistor as to where it connects. The numbers on the left indicate the LCD PCB connection and the ones on the right, the MEGA 2560 connections. Here is how to fix the board.

    1. Unsolder and discard the four resistors in the red square
    2. Solder a wire from 38 to 53 - this is the only connection that was correct.
    3. Solder a wire from 37 to 51
    4. Solder a wire from 36 to 52
    5. Solder a wire from 35 to 50

    And that should do it. I ran both tinyFAT and SDFat and they both worked flawlessly

    Hope this helps,

    Craig Lindley

  • Craig,
    I removed the resistors between 35&51, and 37&52. then soldered a wire from 35 to 52 and 37 to 51.

    So, removed two resistors and soldered two wires.

    tinyFAT and UTFT_tinyFAT work great.

    Erik
  • Do you have the 1.0 version of the shield? I first tried the change you suggest and it didn't work on my shield. It couldn't have because there were three traces in error. Anyway I would have Sainsmart would correct the shield so it works out of the box for everyone.

    Cheers
  • You are correct, I have the 1.0 version of the shield. The shield works great, but I should not have to "adjust" things to get the SD card working.
  • Please both of you, check what you are saying (no offense) because I think you mix numbers or something! I also have 1.0 of that shield, here is how it is wired by default:

    35 to 50
    36 to 51
    37 to 52
    38 to 53

    I have double (even triple) checked, see the picture below:
    http://i.solidfiles.net/9eaa619dec.png


    So, do we all agree that only 36 and 37 (the ones in my picture) must be reversed so that the correct connexions are:

    35 to 50
    36 to 52
    37 to 51
    38 to 53

    Right?? I mean, like in this picture

    http://www.hostingpics.net/viewer.php?id=2478242012091119152479.jpg

    I just want to be sure :)

    Anyway, I'm not even sure I will make this modification, because I will maybe use wires to connect the display to that shield, so just reversing wires 36 and 37 will have the same effect than this modification...right?? But I would like to use a nice and clean IDE 40 pins cable extender so I don't know what I will do really...
  • guix,
    I did it exactly like the photo at: http://www.hostingpics.net/viewer.php?id=2478242012091119152479.jpg

    removing the resistors and adding two short wires...this was done on a v1.0 board. I am using a 6 inch 40 pin cable to connect the lcd to the board, not an IDE cable...I picked up this to connect the LCD:

    https://www.adafruit.com/products/826

    I didn't get it from adafruit...not sure where I got it...maybe ebay...but it works great...

    Erik
  • It seems, that sainsmart don't care about version numbers.
    I have also a 1.0 shield and they have now the correct wires and 0 Ohm resistors.

    Anyway, i have an other problem.

    When i supply the mega2560 via the USB Power, the SD card works very well.
    But if i use an external power supply, it dont work.
    The TFT and the Touch works fine as well only the the SD card dont work.

    When i look to the schematic, there should not be a difference between the power supplay by USB or external.

    I have tried it with a battery, because i thought there is an unproper power.
    But there i have the same problem.

    Anybody an idea what i can do?

    Beginner

  • It should not make a difference unless the power supply is not supplying enough to run everything...

  • Indeed SainSmart doesn't care about board revisions. It is a shame they have a bad reputation because of this, as the products are very well made and of good quality and low price.

    I've been hacking away at the 1.0 shield and LCD for almost a week. Finally I traced all of the pins myself from the LCD board to the Mega. Yes, it appears that pins 51 and 52 are incorrect. The clock pin and MOSI pins are backwards, so no wonder it doesn't work!!!. The CS and MISO pins appear to be correct. I am going to try this modification and then post again with my results. For the record, here is how the pins are INCORRECTLY wired on version 1.0 of the TFT shield...

    CS Mega pin 53
    MOSI Mega pin 52 (incorrect)
    CLK Mega pin 51 (incorrect)
    MISO Mega pin 50
  • that error with the crossed SD_SCK and SD_DIN carries through to the "adaptor.pdf" schematic that sainsmart have. I wasted time as I was referring to that to connect the LCD to the micro. luckily had ordered the LCD adaptor shield also, so I saw the difference between the schematic and what was actually on the board, 0R resistors and buzzed out the fixed SD_SCK / SD_DIN lines compared to the schematic.
    Look like the boards been updated to correct the issues, but if your trying to use the schematic to interface directly, it misguides.

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