System Time R5

The uz_SystemTime can be used to read the total uptime of the UltraZohm and the number of executed ISR routines on the R5 processor. See uz/uz_SystemTime/uz_SystemTime.h for API.

  • Counter with 64-bit at 100 MHz for the uptime of the system.

  • Uses Xilinx AXI Timer v2.0

  • 64 Bit Mode enabled

  • Timer will overflow in >5000 years after system boot

  • Works with two 32-bit counter (lower and upper bits)

  • Only one instance of system time is possible and only on the R5


  • Include uz/uz_SystemTime/uz_SystemTime.h and call the API

  • Intended for usage in the ISR of the R5 processor

  • Initialize the function outside of the ISR by calling uz_SystemTime_init()

  • Call uz_SystemTime_ISR_Tic() to start a time measurement, e.g., the first line of ISR

  • Call uz_SystemTime_ISR_Toc() to stop the time measurement, e.g., last line of ISR

  • Call the getter functions to read the system time that was read by the last tic call

  • A lock prevents the call to toc before tic was called

  • Calling toc before tic fires an assertion

  • Calling any function of the component before uz_SystemTime_init() fires an assertion


The getter functions, e.g., uz_SystemTime_GetUptimeInMs(), return the system time that was read out at the last call to uz_SystemTime_ISR_Tic()! This is intended behavior to have the system time aligned with the start of the ISR.


The variable uptimeInMs holds the uptime in milliseconds at the start of ISR_Control. The variable IsrExectionTimeInUs holds the execution time of the ISR, which will be about 100 microseconds + some time for reading the timer.

void ISR_Control(void *data)
  float uptimeInMs=uz_SystemTime_GetUptimeInMs();
  usleep(100); // Do nothing for 100 microseconds

int main (void){
float IsrExectionTimeInUs=uz_SystemTime_GetIsrExectionTimeInUs();


  • The AXI Timer v2.0 IP-Core is abstracted by uz_AxiTimer64Bit.h which wraps the Xilinx drivers (xtmrctr.h)

  • Timer is called timer_uptime_64bit in Vivado Block Design


Fig. 64 timer_uptime_64bit IP-Core for system time