Real Time Clock Definition

Declares a Real Time Clock (RTC) device

Block ID

Library

motohawk_datetime_lib/Real Time Clock Blocks

Description

A Real Time Clock device keeps track of the current time. It has its own alternate source of power which allows it to continue to keep time when device primary source of power is unavailable. This backup source of power might be a lithium battery or supercapacitor. The time can be set once during start-up (in most cases) or each time user needs to perform this operation (eg. day light saving/time zone change).

The time may be set using a Real Time Clock Set block.

To read the time, use a Real Time Clock Read block. Generally the read rate should be limited to about once a second, which in many cases is the resolution of the hardware device in use.

Real Time Clock (RTC) use a crystal oscilator which frequency in most cases is 32.768kHz which gives exactly 2e15 cycles per second ,convenient rate to use with binary counter circuits. The oscilator might be stoped or interrupted during runtime for various reasons, which can be reported by the Real Time Clock Status block. In this case time provided by RTC device is invalid and has to be set again.

Block Parameters

Parameter Field	Values	Comments/Description
Name	Alpha-numeric text, single-quote enclosed	This parameter defines unique identifier which is used as a reference for Real Time Clock Set, Real Time Clock Read and Real Time Clock Status blocks. The name should be unique and C-legal (no special characters, such as spaces, dashes or commas (underscore allowed).
Resource	Drop-down list	Module resource.
Enable RTC by default	Checkbox	Controls whether the RTC clock is enabled(running) or disabled(halted).
Allow parameter marked with* to be calibrated	Checkbox	Allow user to control input configuration mode through calibration.
Read Access Level	0-8	Sets security level 0 lowest, 8 highest, for user access to read value.
Write Access Level	0-8	Sets security level 0 lowest, 8 highest, for user access to write value.
Instrumentation Group	Alpha-numeric text, single-quote enclosed	Determines Folder name and hierarchy. Use "\|" character between folder names to delineate subgroup structure.