SPRUJ79 November 2024 F29H850TU , F29H859TU-Q1
As part of DLT, time-stamping is done internally for every entry in the FIFO. This is a simple scheme of continuously running counters, and not clock time. Since the structure of DLT code is such that every data set comes with TAG identifier, two counters are used, one for TAGs and the other for REGs. The time-stamping structure has been split to give higher granularity to the TAG inputs.
TIMER1 is exported with TAGS and is a 45 bit timer. TIMER1's value is derived from the 64-bit IPC timer outside DLT.
The TIMER2 is exported with REGS. This indicates the time-difference from the last reported TAG value. TIMER2 is an internal counter.
Also, from a use case perspective, the relative time-stamp of data (REGs) with respect to TAGs gives a clear indication of the code performance for the section. To compare across different sections of code, the absolute values from TAGs can be compared.
TIMER 2 has reset controls that stop the timer and resets the timer to 0. In addition, whenever a new TAG is received and passes through the filters, the TIMER1 overflow, TIMER2 overflow and TIMER2 counter are also reset, so that the relative value is now computed from the newly received TAG.
In case there is a data logging section that is interrupted and a new TAG is received, the relative time and TAG filtering of the subsequent entries is calculated based on Interrupt TAG. It is recommended to use TAG filtering at the start of every ISR or function call, followed by the registers to be data logged.