Real SD card locker based on Attiny85

You probably are familiar with SD card lock switch. It is supposed to write protect the contents of memory once switched to “Write Protect” position. But fact is that there are many SD readers and sockets that simply ignore this switch and no matter what position switch is on, you can write to this card. So this is not the best way to protect data. But there is a way out. SD card has an internal TMP_WRITE_PROTECT bit in CSD register. So if this bit is set, you cannot write to to card – just read. There are other protection layers here like PERM_WRITE_PROTECT bit in same CSD register which can be set once and you get permanent read-only SD card. This one probably is less practical as you are … Continue reading

DIY a Top-Drawer SD Card Read/Write with Arduino For Yourself!

Do you wish to have a small and portable SD Card Read/Write with Arduino, but it’s somewhat costly to buy it from the RadioShack? Well, then just Do It Yourself and you definitely can cut off the budget cost for sure. For today project, you must refer to the below schematic diagram. As you’ve noticed that the above schematic uses some resistors in a voltage divider, and its main point is to bring down the Arduino 5V logic to the SD Cards 3v3 logic. By this way, all the outgoing signals from the Arduino will constantly dropped to 3v3. When the 3v3 is above logic 1 for the Arduino, then the incoming signals to the Arduino are fined. In other hand, the 3v3 voltage supply from the decimelia was normally … Continue reading