MIFARE ULTRALIGHT AND NTAG2x3 EMULATOR

Latest News


2019-02-08

Emutag is back in stock!

Message to clients from the seller:

My apologies for stock shortage for a very long period of time. A new small batch is finally ready, but limited quantity remaining! I've received many emails, and will answer everything soon, except stock-related questions. Emutag was really out of stock, and it took a long time to prepare a new manufacturing sample with a new factory. The production from the old factory needed manual repair of each unit, which resulted in this delay of preparing a new batch in time. Also there were many returns and exchanges due to firmware corruption, and this problem has been addressed and solved successfully.


2019-02-05

Firmware patch to fix EEPROM and Flash memory corruption

The issue

During the year 2017 many users of 3D printers have reported issues with Emutag becoming bricked after running a long print job on batteries. The fix immediately proposed was to run Emutag with external 5V DC power without batteries or to make a small hardware modification with 2 diodes to choose the power source automatically, depending on what power source has the highest voltage. The cause is described on the How-To's page.

Patch overview

A recent glance at the ATtiny4313 microcontroller datasheet revealed that the brown-out detection function, set by fuse bits, can be controlled in runtime. Brown-out detection prevents the microcontroller from running any instructions if the supply voltage gets too low, thus preventing firmware corruption. However, it needs 20 µA of current to operate. This is negligible in runtime, but would empty the batteries in a month in standby mode. Before this patch, the brown-out detection function was completely disabled. With the new possibility of disabling brown-out detection during standby mode only, this protection feature can now be applied during code execution, avoiding accidental code overwrite by incorrectly decoded instructions while running at unsafely low voltage.

Changes required

All Emulators sold since 2019 have this patch already applied, so there is nothing to do. If you need to apply this patch (which is recommended anyway), Emutag needs to be completely reflashed, including Flash, EEPROM, and fuse area. The instructions have been updated, and changes in flashing commands have been highlighted in red. The same new instructions work independently of the firmware version currently flashed in. All updated firmware files have their names ending with "-LVRpatch.bin" (LVR - Low Voltage Reset).

WARNING! Please note that updating both Flash and fuses is required. If only Flash is updated, there is no effect. If only fuses are updated, Emutag will start draining 20 µA during sleep mode, which will empty the batteries in about a month.