Visible to Intel only — GUID: iga1401398648385
Ixiasoft
Visible to Intel only — GUID: iga1401398648385
Ixiasoft
23.4.1. HAL System Library Support
Intel provides a driver for both the HAL timer device models: system clock timer, and timestamp timer.
System Clock Driver
When configured as the system clock, the interval timer core runs continuously in periodic mode, using the default period set. The system clock services are then run as a part of the interrupt service routine for this timer. The driver is interrupt-driven, and therefore must have its interrupt signal connected in the system hardware.
The Nios® II integrated development environment (IDE) allows you to specify system library properties that determine which timer device will be used as the system clock timer.
Timestamp Driver
The interval timer core may be used as a timestamp device if it meets the following conditions:
- The timer has a writeable period register, as configured in Platform Designer.
- The timer is not selected as the system clock.
The Nios® II IDE allows you to specify system library properties that determine which timer device will be used as the timestamp timer.
If the timer hardware is not configured with writeable period registers, calls to the alt_timestamp_start() API function will not reset the timestamp counter. All other HAL API calls will perform as expected.
For more information about using the system clock and timestamp features that use these drivers, refer to the Nios® II Software Developer’s Handbook. The Nios® II Embedded Design Suite (EDS) also provides several example designs that use the interval timer core.
Limitations
The HAL driver for the interval timer core does not support the watchdog reset feature of the core.