Difference between revisions of "LPC1768: RTC Programming"

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[[category: LPC1768 Tutorials]]
 
[[category: LPC1768 Tutorials]]
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---
+
In this tutorial we will be discussing about the internal RTC of LPC1768. We will see what are the different registers associated with the RTC but we will mainly focus on basics registers required to use RTC. Later we will see how to use Explore Embedded library for RTC.<br><br><br>
  
−
=Objective=
 
 
=RTC Registers=
 
=RTC Registers=
 +
The RTC includes a number of registers. We will concentrate some of the basic required registers.
 +
{| class="table table-striped table-hover table-condensed table-bordered"
 +
|-class="info"
 +
|Register|| Description 
 +
|-
 +
| CCR || Clock Control Register
 +
|-class="active"
 +
|colspan= '2'|'''Consolidated Time Registers'''
 +
|-
 +
|CTIME 0|| Consolidated Time Register 0
 +
|-class="active"
 +
|CTIME 1|| Consolidated Time Register 1
 +
|-
 +
|CTIME 2|| Consolidated Time Register 2
 +
|-class="active"
 +
|colspan = '2'|'''Time Counter Registers'''
 +
|-
 +
|SEC || Seconds Counter
 +
|-class="active"
 +
|MIN || Minutes Register
 +
|-
 +
|HOUR || Hours Register
 +
|-class="active"
 +
|DOM || Day of Month Register
 +
|-
 +
|DOW || Day of Week Register
 +
|-class="active"
 +
|DOY || Day of Year Register
 +
|-
 +
|MONTH || Months Register
 +
|-class="active"
 +
|YEAR || Years Register
 +
|-
 +
|CALIBRATION || Calibration value Register
 +
|}
 +
<br><br><br><br>
  
−
 
+
=RTC Register Configuration=
−
=====CCR ( Clock Control Register )=====
+
Lets see how to configure these registers.
−
{| class="wikitable" style="text-align:center; background-color:#ABCDEF;margin: 1em auto 1em auto"
+
{| class="table table-striped table-hover table-condensed table-bordered"
−
!colspan = '9'|CCR  
+
|-class="info"
 +
|CCR
 
|-
 
|-
 
|31:5|| 4 || 3:2|| 1|| 0   
 
|31:5|| 4 || 3:2|| 1|| 0   
−
|-
+
|-class="active"
 
| - || CCALEN || - || CTCRST || CLKEN
 
| - || CCALEN || - || CTCRST || CLKEN
 
|}
 
|}
 +
=====CCR ( Clock Control Register )=====
 +
The Clock Control Register register controls the operation of the clock divide circuit.
  
 
'''Bit 0 – CLKEN : Clock Enable'''<br>
 
'''Bit 0 – CLKEN : Clock Enable'''<br>
 +
This bit is written with one to enable time counters and written with zero to disable time counters.
  
 
'''Bit 1 - CTCRST : CTC Reset'''<br>
 
'''Bit 1 - CTCRST : CTC Reset'''<br>
 +
When this bit is set to one, the internal oscillator divider are reset.
  
−
'''Bit 3:2 '''
+
'''Bit 3:2 - Reserved'''<br>
 +
These bits must be set to zero for normal RTC operation.
  
−
'''Bit 4 - CCALEN''' <br>
+
'''Bit 4 - CCALEN : Calibration counter enable''' <br>
 +
To disable calibration counter and reset it to zero, write one to this bit.
 +
When written zero, the counter is enabled and starts counting
  
−
'''Bit 31:5 '''
+
'''Bit 31:5 - Reserved'''<br><br><br><br><br>
  
 
=====Time Counter Register =====
 
=====Time Counter Register =====
−
{| class="wikitable" style="text-align:center; background-color:#ABCDEF;margin: 1em auto 1em auto"
+
The time value consists of the eight counters and there is separate register associated with each counter.  To update the RTC, new values should be written to these registers.
−
!colspan = '9'|Time Counter Register
+
{| class="table table-striped table-hover table-condensed table-bordered"
 +
|-class="info"
 +
|Time Counter Registers 
 
|-
 
|-
−
|Name|| Description || Range 
+
|Register|| Description || Minimum Value || Maximum Value
 +
|-class="active"
 +
|SEC || Seconds value|| 0 || 59
 
|-
 
|-
−
|SEC || Seconds value|| 0 to 59
+
|MIN || Minutes value|| 0 || 59
 +
|-class="active"
 +
|HOUR || Hours value|| 0 || 23
 
|-
 
|-
−
|MIN || Minutes value|| 0 to 59
+
|DOM || Day of Month value|| 1 || 28,29,30 or 31(depending on the month)
 +
|-class="active"
 +
|DOW || Day of Week value|| 0 || 6
 
|-
 
|-
−
|HOUR || Hours value|| 0 to 23
+
|DOY || Day of Year value|| 1 || 365 (366 for Leap Year)
 +
|-class="active"
 +
|MONTH || Month value|| 1 || 12
 
|-
 
|-
−
|DOM || Day of Month value|| 1 to 28,29,30 or 31 <br> ( depending on the
+
|YEAR || Year value|| 0 || 4095
−
month and whether it is a leap year).
+
|}<br><br>
 +
 
 +
===== Consolidated Time Registers =====
 +
 
 +
The values of the Time Counters can optionally be read in a consolidated format which
 +
allows the programmer to read all time counters with only three read operations.
 +
 
 +
There are 3 Consolidated Time Registers. The minimum and maximum values of the various fields in these registers are same as the respective Time Counter Register.
 +
 
 +
These registers are read only. New values should be written to Time Counter Registers.
 +
 
 +
 
 +
{| class="table table-striped table-hover table-condensed table-bordered"
 +
|-class="info"
 +
|Consolidated Time Register 0 ( CTIME0 )
 +
|--class="active"
 +
| 31:27 || 26:24 || 23:21 || 20:16 || 15:14 || 13:8 || 7:6 || 5:0
 
|-
 
|-
−
|DOW || Day of Week value|| 0 to 6
+
| Reserved || Day of Week || Reserved || Hours || Reserved || Minute || Reserved || Second
−
|-
+
|}
−
|DOY || Day of Year value|| 1 to 365 (366 for Leap Year)
+
−
|-
+
 
−
|MONTH || Month value|| 1 to 12
+
{| class="table table-striped table-hover table-condensed table-bordered"
 +
|-class="info"
 +
|Consolidated Time Register 1 ( CTIME1 )  
 +
|--class="active"
 +
| 31:27 || 27:16 || 15:12 || 11:8 || 7:5 || 4:0
 
|-
 
|-
−
|YEAR || Year value|| 0 to 4095
+
| Reserved || Year || Reserved || Month || Reserved || Day of Month
 
|}
 
|}
  
−
=Steps for configuring RTC=
+
 
−
=Code EXample=
+
{| class="table table-striped table-hover table-condensed table-bordered"
 +
|-class="info"
 +
|Consolidated Time Register 2 ( CTIME2 )
 +
|--class="active"
 +
| 31:12 || 11:0
 +
|-
 +
| Reserved || Day of Year
 +
|}<br><br><br>
 +
 
 +
=Steps for Using RTC=
 +
=== Initialize RTC ===
 +
* Disable RTC clock using CCR ( Clock Control Register )
 +
* Reset clock using CCR register
 +
* Enable RTC calibration in RTC Calibration Register
 +
* Enable the clock for RTC using CCR register
 +
 
 +
=== Set Date and Time ===
 +
As we saw previously, there are separate Time Counter registers for each time parameter hour, min, sec and same is the case date. We just need to copy the required values to these registers.
 +
 
 +
=== Read Date and Time===
 +
The values of date and time can be read from associated Time Counter registers.
 +
Alternately, date and time can also be read from Consolidated Time registers.
 +
 
 +
We will use Time Counter registers for both reading and writing.<br><br><br><br>
 +
 
 +
=Code Example=
 
===Example 1 ===
 
===Example 1 ===
−
===Using Explore Embedded Liberaries===
+
 
 +
In this example we will see how to use lpc1768 inbuilt RTC. The time and date will be displayed continuously on 2x16 LCD.
 +
 
 +
<html>
 +
<script src="https://gist.github.com/SaheblalBagwan/08ad5b3998d8d3a98fd03fc784db7c22.js"></script>
 +
</html>
 +
<br><br><br><br>
 +
 
 +
===Using Explore Embedded Libraries===
 +
 
 +
Now we will discuss how to use Explore Embedded Libraries for LPC1768 inbuilt RTC.
 +
Refer the LCD tutorial for interfacing the 2x16 lcd.
 +
 
 +
<html>
 +
<script src="https://gist.github.com/SaheblalBagwan/7e34857b78d611d996a32cadf1467d14.js"></script>
 +
</html>
 +
<br><br><br><br>
 +
 
 +
=Connection=
 +
Do the connections as shown the below image and flash the compiled code.
 +
[[File:LPC1768_RTC.jpg]]
 +
 +
 
 +
= Downloads=
 +
Download the complete project folder from the below link:
 +
https://codeload.github.com/ExploreEmbedded/Explore-Cortex-M3-LPC1768-Stick-DVB-14001/zip/master<br><br>
 +
 
  
 
{{DISQUS}}
 
{{DISQUS}}

Latest revision as of 17:50, 19 July 2016

In this tutorial we will be discussing about the internal RTC of LPC1768. We will see what are the different registers associated with the RTC but we will mainly focus on basics registers required to use RTC. Later we will see how to use Explore Embedded library for RTC.


RTC Registers

The RTC includes a number of registers. We will concentrate some of the basic required registers.

Register Description
CCR Clock Control Register
Consolidated Time Registers
CTIME 0 Consolidated Time Register 0
CTIME 1 Consolidated Time Register 1
CTIME 2 Consolidated Time Register 2
Time Counter Registers
SEC Seconds Counter
MIN Minutes Register
HOUR Hours Register
DOM Day of Month Register
DOW Day of Week Register
DOY Day of Year Register
MONTH Months Register
YEAR Years Register
CALIBRATION Calibration value Register





RTC Register Configuration

Lets see how to configure these registers.

CCR
31:5 4 3:2 1 0
- CCALEN - CTCRST CLKEN
CCR ( Clock Control Register )

The Clock Control Register register controls the operation of the clock divide circuit.

Bit 0 – CLKEN : Clock Enable
This bit is written with one to enable time counters and written with zero to disable time counters.

Bit 1 - CTCRST : CTC Reset
When this bit is set to one, the internal oscillator divider are reset.

Bit 3:2 - Reserved
These bits must be set to zero for normal RTC operation.

Bit 4 - CCALEN : Calibration counter enable
To disable calibration counter and reset it to zero, write one to this bit. When written zero, the counter is enabled and starts counting

Bit 31:5 - Reserved




Time Counter Register

The time value consists of the eight counters and there is separate register associated with each counter. To update the RTC, new values should be written to these registers.

Time Counter Registers
Register Description Minimum Value Maximum Value
SEC Seconds value 0 59
MIN Minutes value 0 59
HOUR Hours value 0 23
DOM Day of Month value 1 28,29,30 or 31(depending on the month)
DOW Day of Week value 0 6
DOY Day of Year value 1 365 (366 for Leap Year)
MONTH Month value 1 12
YEAR Year value 0 4095


Consolidated Time Registers

The values of the Time Counters can optionally be read in a consolidated format which allows the programmer to read all time counters with only three read operations.

There are 3 Consolidated Time Registers. The minimum and maximum values of the various fields in these registers are same as the respective Time Counter Register.

These registers are read only. New values should be written to Time Counter Registers.


Consolidated Time Register 0 ( CTIME0 )
31:27 26:24 23:21 20:16 15:14 13:8 7:6 5:0
Reserved Day of Week Reserved Hours Reserved Minute Reserved Second


Consolidated Time Register 1 ( CTIME1 )
31:27 27:16 15:12 11:8 7:5 4:0
Reserved Year Reserved Month Reserved Day of Month


Consolidated Time Register 2 ( CTIME2 )
31:12 11:0
Reserved Day of Year



Steps for Using RTC

Initialize RTC

  • Disable RTC clock using CCR ( Clock Control Register )
  • Reset clock using CCR register
  • Enable RTC calibration in RTC Calibration Register
  • Enable the clock for RTC using CCR register

Set Date and Time

As we saw previously, there are separate Time Counter registers for each time parameter hour, min, sec and same is the case date. We just need to copy the required values to these registers.

Read Date and Time

The values of date and time can be read from associated Time Counter registers. Alternately, date and time can also be read from Consolidated Time registers.

We will use Time Counter registers for both reading and writing.



Code Example

Example 1

In this example we will see how to use lpc1768 inbuilt RTC. The time and date will be displayed continuously on 2x16 LCD.





Using Explore Embedded Libraries

Now we will discuss how to use Explore Embedded Libraries for LPC1768 inbuilt RTC. Refer the LCD tutorial for interfacing the 2x16 lcd.





Connection

Do the connections as shown the below image and flash the compiled code. LPC1768 RTC.jpg


Downloads

Download the complete project folder from the below link: https://codeload.github.com/ExploreEmbedded/Explore-Cortex-M3-LPC1768-Stick-DVB-14001/zip/master


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