My problem was that a makeshift 3.3v supply from a voltage divider seemed to work for the raw SD write, but not for the full uFAT mmc code.
SD CARD WRITER CODE
Hi - I wanted you to know that I got the mmc1.rar code for uFAT working, just as advertised. Serial.print(disk_info.flag_write_protect,DEC) Serial.print(disk_info.flag_write_protect_temp,DEC) Serial.print(disk_info.manufacturing_year,DEC) Serial.print(disk_info.manufacturing_month,DEC) Serial.println("send q to stop sampling") Serial.println("send s to start sampling") Serial.println("MMC/SD initialization failed") I haven’t done much testing about read and write speeds or buffer size, in this example I’m only storing 2 bytes in a temporary buffer and then writing them to the card. You can read back the sd card by sending an ‘r’. It takes samples from analog in 1 and writes them to the sd card when you send an ‘s’ over serial.
When the library starts it reads the card info and prints it out.
SD CARD WRITER HOW TO
Here is the code for a very basic data logger which shows how to use the library. Once you do that and restart the build environment you should be able to select SDcard as an added library and it will add the necessary includes. for me it is arduino-0011/hardware/libraries/SDcard ). Copy the files into the library directory in the arduino build environment. I haven’t tried to convert it to a cpp library. This lets you write and read byte values from an sd card. I’ve cutout all the unnecessary files from the roland reigel library and applied the fixes to leave just raw sd card reading and writing. (The other stuff is a real time clock and its parts) There is a thermistor connected to analog1 with some resistors for testing purposes. I desoldered an sdcard socket from a broken memory card reader and then soldered pins onto the bottom. The schematic (all top resistors are 1.8k, all bottom resistors are 3.3k):
The 3v3 voltage supply from the decimelia was used to supply power to the sd card. Incoming signals to the arduino are fine because 3v3 is above logic 1 for arduino. So all outgoing signals from the arduino are dropped to 3v3. The schematic uses some resistors in a voltage divider to drop down the arduino 5v logic to the sd cards 3v3 logic. FAT reading and writing will have to wait until some larger memory arduinos are available as it uses almost all of the memory, leaving no space for further code. After lots of tinkering, and some help from another user (strohhalm who found some fixes in the german forum for the roland-reigel library) it seems to work ok. I started a topic in the development section a while ago about getting an excellent sd/mmc card library ( - sd-reader: MMC/SD/SDHC card library) working in Arduino.
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