The Robotdyn Eth r3 is a nice compact single board for Internet of Things designs. It has the most modern Ethernet chip (W5500) the At Mega 2560 with lots of flash, eeprom, ram, and I/O, and both 5 v and 3.3 volt converters, and a SD card slot with Card Detect.
Before I ask my question, let me state that the Processor with its various memories and the Ethernet are working great, i fully understand the assertive low SPI selects, have tried to run all the SD examples (with appropriate modifications to deselect the Ethernet) , and have read every arduino and adafruit forum discussion I can find where users have had issues with SD initialization. Yes, I am aware of the SPI pins on 50-53. I have scoped the Clk, MISO, MOSI, and SS pins to ensure they are functioning to the card, and have tried two new SDHC class 10 cards (Ultra 32 GB San Disk and a 32 GB generic compliant to SD 2 spec). I have tried the cards as shipped and formatted, also formatted on Windows 10 to FAT32, formatted on a Macbook using the SD format program to FAT32, partitioned to 14 GB and formatted FAT16. The Robotdyne MEGA2560 board does the level convert to 3.3 volts on the CLK, MOSI, and CS using a 74HC244. However, it does not do voltage conversion from the SD card back to the Mega’s MISO pin, instead relying that the SD high level will be detected as a high at the Mega’ MISO and that the SD card will not be damaged by any 5 volt transients at power up and initialization.
In my case, no data is sent back from the SD card on MISO and the SD card is never initialized. Yes, I have sought help with Robotdyn support and they have responded, but I don’t believe they understand assertive low selects, or perhaps it is a language issue. Regardless, their suggestions were not helpful.
My question, has anyone else with a Robotdyne MEGA2560 Eth r3 board had an issue reading Class 10 SD cards formatted as FAT32?
Meanwhile I have ordered several different sizes of SD cards from two other vendors, and also another (in stock at multiple mainland locations) Robotdyn MEGA2560 Eth r3 from Amazon (who has been deliberately sitting on my non-prime order since Monday and not shipped. Today is Thursday.).