SD Card Shield - Required Pins

Other Hardware Storage
1

Hi All

I have an SD Card Shield from Seeed Studio (V4.1 - SD Card shield V4.0 | Seeed Studio Wiki) and a LCD Shield from Linksprite (16 X 2 LCD Keypad Shield for Arduino - LinkSprite Playgound)

From the look of things the ports overlap on the shields so I was wondering if anyone could assist with highlighting which ports to SD card shield uses (I'm not able to determine from schematic on the SD card shield) and also if its possible for me to change the ports required on the shield?

At this stage i am only playing with the "CardInfo" sketch within the arduino software. I am using an Mega 2560.
EDIT - I probably should add, i can see that poirt 4, 11,12,13 are in use but not sure if anything else is in use (ISP ports?)
Regards
Stephen

2

Pin 10 should be set as an OUTPUT pin, to enable SPI, which involves pins 11, 12, and 13. The chip select pin, to define which SPI device is the active receiver is pin 4., which is the pin to use in the SD.begin() call.

The LCD shield uses pins 4 to 9. Why the moronic piece of crap example software uses pin 13 in the constructor is a mystery. Pin 13 is (fortunately) not connected to the LCD shield.

3

Thanks for the Info PaulS. Does that mean that even though i have

LiquidCrystal lcd(8, 13, 9, 4, 5, 6, 7);

I can still put my SD Card shield in and use it? Or do i need to modify that LCD line?

Sorry if this is simple questions as i'm still trying to get my head around the SD card shield.

4

Or do i need to modify that LCD line?

You'll need to look at the LiquidCrystal library, to see what the second argument is for, to have some idea what to change it to. Yes, you will need to change it so that the instance doesn't diddle with pin 13.

5

I am using an Mega 2560.

It appears from the schematic http://www.seeedstudio.com/wiki/images/1/1f/SD_Card_Shiled_v4.0.pdf that the card uses the ISP connector for SPI.

On a Mega pins 50-53 are used for SPI. Pin 4 on the Seeed shield is used for SD chip select so pin 4 can't be used with the LCD.

Edit: I attached pdf of the board file so you can see the used pins.

SD Card v4.0a.pdf (37.8 KB)

6

I can still put my SD Card shield in and use it? Or do i need to modify that LCD line?

It's a shield. those pins are fixed by the pcb traces on the keypad shield. If you had a standalone parallel lcd where you could put the wires anywhere you want then yeah you could modify that line but you have a shield and those pin connections are based on
which pins the traces go to on the button shield so unless you can rewire , there is no point in changing the Lcd Constructor pin configuration in that line.

7

but you have a shield and those pin connections are based on
which pins the traces go to on the button shield so unless you can rewire , there is no point in changing the Lcd Constructor pin configuration in that line.

Have YOU looked at the schematic? There is nothing connected to pin 13.

8

Actually, I was referring to this:

Pin 4 on the Seeed shield is used for SD chip select so pin 4 can't be used with the LCD.

1602+LCD+Shield+Sch.pdf (163 KB)

9

Thanks guys. I might put the SD card shield on the Mega and just wire the LCD in separately.
Appreciate the assistance.