The original TNT323DAC firmware, version 1.0 through 1.2, was functional but flawed. User reports and reverse engineering communities identified three major categories of issues that led to the demand for a patched version.
Read the Original Firmware (Backup)
Using STM32CubeProgrammer or OpenOCD, read the entire flash memory (0x8000000 to 0x800FFFF) and save it as backup_original.bin. Do not skip this step. If the patch fails, this is your recovery.
Erase and Flash the Patched Binary
Erase only the necessary sectors (sectors 0-2). Then flash the tnt323dac_v2.1_patched.bin file at address 0x8000000. tnt323dac firmware patched
Verify
Perform a checksum verification. The ST-Link will confirm a successful write.
Test the Calibration Mode
Power the module via its normal power input (24V DC). Short TP7 to GND before applying power. Open a serial terminal at 115200 baud. You should see the message: "TNT323DAC Patched v2.1 - Calibration Mode Active" The original TNT323DAC firmware, version 1
Reassemble
Remove the temporary programming header (or leave it inside for future updates) and close the enclosure.
The patched firmware is closed-source. Only the binary is distributed. While no malware has been reported, you are placing trust in anonymous community developers. If used in a security-critical system (e.g., a motor controller for a robotic arm), this is a non-trivial risk. Erase and Flash the Patched Binary Erase only
The most celebrated feature of the patched firmware is the "Open Calibration Mode." By shorting two specific test points (TP7 and GND) during boot, the user enters a calibration menu accessible via a serial terminal. This allows writing new zero-scale and full-scale values directly to the on-board EEPROM.