A while ago I received the good-looking I2SD kit from Wyolum. This is another open source project created and generously shared by the same team that brought us ClockTHREE and C3Jr.
The I2SD kit is pictured below. As you can see, it is mostly SMD (0805 and SOIC packages). Not for a novice, but definitely easy to solder by anyone with a steady hand and a good pair of eyes.
As always, when I assemble a kit, I try to skip the "read the manual" part. I don't recommend this to anyone though. This is just a test for me to assess how user-friendly the kit is. (Note: Ironically, this test would fail for my own Wise Clock 3 kit because of the 3 resistors of 4K7. One really need to know exactly where those resistors go (R5, R6 and R7). An improvement in a future version of Wise Clock 3 would be to have the resistor values on the silkscreen, as C3Jr has.)
Well, the I2SD kit passed the "no manual required" test, which means that the kit is well thought and designed. Again, if you are not sure what you are doing, you should not attempt building this kit without reading the documentation first.
The next photos show the top and bottom sides of the assembled I2SD, with the SD card inserted into the socket.
As you can notice from the photos, I2SD has an on-board ATmega328, thus making it an (software-wise) Arduino-compatible. It also has an SD socket, an RTC chip (DS3231) with backup battery, and the 6-pin FTDI connector.
The I2SD was designed to be used as an Arduino storage peripheral, linked with Arduino devices on I2C.
For this purpose, the I2SD runs a sketch that:
- receives "read" commands from a host and returns the required data it reads from the SD card file;
- receives "write" commands from the host and stores the data in the SD card file.
As mentioned above, the I2SD itself can be used as a standalone Arduino (since the ATmega328 has the bootloader). To test it, I uploaded (with the Arduino IDE 22) this sketch which writes to the file TEST.TXT on the SD card.
I2SD can be integrated within many devices requiring data storage and retrieval, ranging from data logging (the RTC chip is definitely helping here), to system configuration, image capturing etc.