RTC standalone driver

Introduction

The Zynq® UltraScale+™ MPSoC real time clock (RTC) provides the real time even when the device is powered off.
When the device is off, the RTC is switched to the battery power supply. A battery-backed RAM (BBRAM) is
provided for when device is operating in the battery mode. However, the RTC controller and user interface are only
operational when the low-power domain supply is ON.
The RTC has an alarm function that generates an alarm at a specific time and date with a 136-year range.
The RTC also has periodic software calibration and logic to correct the static fractional inaccuracy of an oscillator.

How to enable

Source Path for the driver
https://github.com/Xilinx/embeddedsw/commits/master/XilinxProcessorIPLib/drivers/rtcpsu

Driver source code is organized into different folders. Below diagram shows the rtcpsu driver source organization
rtcpsu
|
-- doc - Provides the API and data structure details
|
-- examples - Reference application to show how to use the driver APIs and calling sequence
|
-- src - Driver source files

Features Supported in the driver

Controller Features supported

• Maintains the real time, even when the device is off (powered-off).
• Has the capability to generate an alarm at a specific time and date.
• Includes the means for periodic software calibration of the RTC.
• Includes logic to correct the static fractional inaccuracy of the oscillator.
• Keeps track of time within a window of more than 136 years (232 seconds) from a reference point.
• Implemented as three counters.
  • 16-bit tick counter creates one second based on the crystal clock.
  • 4-bit fraction counter keeps track of the static crystal errors in one second that is less than one oscillator tick.
  • 32-bit seconds counter holds the real time and allows on-demand reload whenever current time of the RTC is set.
• Allows wake-up at a specific second within the 136 years (32-bit alarm)

Driver Supported Features

The RTC Standalone driver support the below things.

• All controller features supported.

Known Issues and Limitations

• None.

Test cases

• Refer below path for testing different examples for each feature of the IP.

https://github.com/Xilinx/embeddedsw/tree/master/XilinxProcessorIPLib/drivers/rtcpsu/examples

• xrtcpsu_alarm_interrupt_example.c : This alarm example uses the XRtcPsu driver in interrupt mode. It sets alarm for a specified time from the current time.
• xrtcpsu_alarm_polled_example.c : This alarm example uses the XRtcPsu driver in polled mode. It sets alarm for a specified time from the current time.
• xrtcpsu_periodic_alarm_interrupt_example.c : This periodic alarm example using the XRtcPsu driver in interrupt mode. It sets periodical alarm for specified times from the current time. For demontration purpose, a periodic alarm for future 2Secs was implemented for 10 such events.
• xrtcpsu_seconds_interrupt_example.c : This seconds example uses the XRtcPsu driver in interrupt mode.
• xrtcpsu_seconds_polled_example.c : This seconds example uses the XRtcPsu driver in polled mode.
• xrtcpsu_set_calibration_example.c : This example uses the XRtcPsu driver to update the calibration register value.
• xrtcpsu_set_time_example.c : This example uses the XRtcPsu driver to update the current time.

Change Log

• 2017.1

  • Summary
    • rtcpsu : Fixed compilation warnings
    • RTCPSU : Corrected calibration and frequency macros.
    • rtcpsu: Added readme.txt file to generate doxygen for examples
  • Commits
    • dc92361 : rtcpsu : Fixed compilation warnings.
    • 91ee3a6 : RTCPSU : Corrected calibration and frequency macros.
    • 49a6a78 : rtcpsu: Added readme.txt file to generate doxygen for examples.

• 2017.2

  • Summary
    • rtcpsu: Modified filename tag in examples
  • Commits
    • d65236a : rtcpsu: Modified filename tag in examples

• 2017.3

  • Summary
    • rtcpsu: Fixed compilation warnings
    • rtcpsu: Code cleanup
  • Commits
    • 61974ae : rtcpsu: Fixed compilation warnings.
    • dc74ed7 : rtcpsu: Code cleanup.

• 2018.1

  • None

• 2018.2

  • None

• 2018.3

  • None

• 2019.1

  • Summary
    • rtcpsu: Fixed MISRA-C warnings
  • Commits
    • cd670ac: MISRA-C:No brackets to loop body
    • f79d426: MISRA-C:No brackets to then/else
    • e8eb02a: MISRA-C:Casting operation to a pointer
    • fc917b6: MISRA-C:Array has no bounds specified
    • dddc939: MISRA-C:Literal value requires a U suffix
    • b37d04e: MISRA-C:Logical conjunctions need brackets
    • dd928e7: MISRA-C:Pointer param should be declared pointer to const
    • 405723b: Updated year and change version history

• 2019.2
  • Summary
    • rtcpsu: Corrected calibration algorithm
    • rtcpsu: Updated set calibration example with right sequence
  • Commits
    
    • 575af1b1  rtcpsu: Corrected calibration algorithm
    • 09ec4457 rtcpsu: Updated set calibration example with right sequence

• 2020.1

  • None

• 2020.2

  • Summary
    • rtcpsu: Update Makefile for parallel make execution
    • rtcpsu: MISRA-C fixes
  • Commits
    • ab20b8 rtcpsu: Update Makefile for parallel make execution
    • 92526b rtcpsu:MISRA-C: Remove const keyword
    • ea1f2b rtcpsu: Fixed MISRAC rule 4.5 violation
    • c41c38 rtcpsu: Fixed MISRAC rule 10.4 violation
    • 8a0f2d rtcpsu: Fixed MISRAC rule 10.6 violation
    • ac9a95 rtcpsu: Fixed MISRAC rule 10.3 violation
    • f8fe2f rtcpsu: Fixed MISRAC rule 8.4 violation