I recently purchased an Adafruit Datalogger Shield. It worked with my Arduino Uno, but I cannot get it to use the SD part with my Elegoo Mega2560 R3. I have been testing with the cardinfo example and have made sure that the chipSelect pin is accurate. The RTC does work with it. I have tryed both steps listed on the Adafruit website at Data Logging Shield (Assembled) | Adafruit Shield Compatibility Guide | Adafruit Learning System. Any suggestions?
Have you seen the modification suggestions needed for use with other boards, which are described in the link you posted yourself?
Incompatible or Partially-Compatible Boards
This shield may work with other boards with some additional steps:
Arduino Leonardo
The RTC is compatible. For the SD card, the following may be tried, in decreasing order of recommendation:Use the Adafruit SD library, specifying pin 10 for chip select, 11 for MOSI, 12 for MISO and 13 for SCK.
Edit the file utility/Sd2Card.h in the default Arduino SD library, adding the line "#define SOFTWARE_SPI" (not MEGA_SOFT_SPI) at the top.
Add jumper wires from pin 11 on the shield to ICSP pin 4 on the board (on the 6-pin header), pin 12 to ICSP-1 and pin 13 to ICSP-3, then use the standard library in its default state (no SOFTWARE_SPI). This is difficult due to the shield obscuring the ICSP header and is not much recommended.Arduino Mega 2560 R3 or Mega ADK
The RTC is compatible. For the SD card, the following may be tried, in decreasing order of recommendation:Use the Adafruit SD library, specifying pin 10 for chip select, 11 for MOSI, 12 for MISO and 13 for SCK.
Edit the file utility/Sd2Card.h in the default Arduino SD library, changing line 42 to read "#define MEGA_SOFT_SPI 1" (default is 0).Arduino Mega 2560 R2 & Earlier
RTC:Add jumper wire from SDA on shield to pin 20 on Mega board.
Add jumper wire from SCL on shield to pin 21 on Mega board.For the SD card, the following may be tried, in decreasing order of recommendation:
Use the Adafruit SD library, specifying pin 10 for chip select, 11 for MOSI, 12 for MISO and 13 for SCK.
Edit the file utility/Sd2Card.h in the default Arduino SD library, changing line 42 to read "#define MEGA_SOFT_SPI 1" (default is 0).Arduino Due
The RTC is compatible (when using latest library). Accessing the SD card is possible with the addition of some jumper wires, but difficult due to the fact that the shield obscures the ICSP header where these wires must be connected.Add jumper wire from pin 11 on shield to ICSP pin 4.
Add jumper wire from pin 12 to ICSP pin 1.
Add jumper wire from pin 13 to ICSP pin 3.Use the standard SD library (not the Adafruit fork). Do NOT #define SOFTWARE_SPI or MEGA_SOFT_SPI in the library.
ELEGOO MEGA 2560 R3 Board Black ATmega2560 ATMEGA16U2
The Mega is 100% compatible with Arduino and most shields designed for the Arduino
The chip is Atmega2560-16au and Atmega16u2, same with the official version.
Improved and expert version: 1.0 pinout: added SDA and SCL pins that are near to the AREF pin and two other new pins placed near to the RESET pin, the IOREF that allow the shields to adapt to the voltage provided from the board. In future, shields will be compatible both with the board that use the AVR, which operate with 5V and with the Due that operate with 3.3V. The second one is a not connected pin, that is reserved for future purposes.
https://www.elegoo.com/product/elegoo-mega-2560-r3-board-atmega2560-atmega16u2-usb-cable/