5.2.3 TSCAL Data from OTP in Production
In production, the TSCAL data must be read from its dedicated packet in the OTP User Area. Therefore, the first step is to write this packet in the OTP. The SAM-BA tool provides OTP commands to perform the packet copy from SRAM/SECURAM to OTP. Refer to the SAM-BA documentation (see Reference Documents).
- Any writing in the OTP user area disables further usage of the OTPC Emulation mode.
- To further prevent the ROM code from copying the data into SRAM and SECURAM, it is good practice to disable the packet copy feature by writing the word ENG_PKT_COPY_DIS in the Boot Configuration Packet.
Once the OTP area is written, the application accesses the TSCAL data by reading the appropriate packet in the OTP.
Note that the physical address of this packet in the OTP memory may vary from device to device, therefore identifying this packet must be done by searching for a regular packet with a payload that starts with a 32-bit word programmed to the constant value “TSCA”.
The same identification methodology can be applied during prototyping when using the OTP Emulation mode.