Difference between revisions of "LPC1768: Switch and LED"

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[[category: LPC1768 Tutorials]]
 
[[category: LPC1768 Tutorials]]
  
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This is second tutorial on LPC1768 where we are going to read the switches and turn ON/OFF the LEDs accordingly.
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=Objective=
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LPC1768 has its GPIOs divided into five ports PORT0 - PORT4, although many of them are not physically 32bit wide. Refer the data sheet for more info.
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This is Second example on LPC1768 where we are going to read the switchs and turn ON/OFF the LEDs accordingly.
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<br><br>
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=Register Configuration=
 
=Register Configuration=
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As all the LPC1768 SFRs(Special Function Registers) are defined in lpc17xx.h, this has to be included at the beginning of our project/code.
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The Below registers will be used for Configuring and using the GPIOs registers for sending and receiving the Digital signals.
  
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LPC1768 has its GPIOs divided into five ports PORT0 - PORT4, although many of them are not physically 32bit wide. Refer the data sheet for more info.
 
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The Below registers will be used for Configuring and using the GPIOs registers for sending and receiving the Digital signals.
 
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A structure LPC_GPIOn(n= 0,1,2,3) contains all the registers for required for GPIO operation. Refer lpc17xx.h file for more info on the registers.
 
  
  
 
<b>PINSEL:</b> GPIO Pins Select Register<br>
 
<b>PINSEL:</b> GPIO Pins Select Register<br>
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Almost all the LPC1768 pins are multiplexed to support more than 1 function. Every GPIO pin has a minimum of one function and max of four functions. The required function can be selected by configuring the PINSEL register. As there can be up to 4 functions associated with a GPIO pin, two bits for each pin are available to select the function. This concludes that we need two PINSEL registers to configure a PORT pins.
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Almost all the LPC1768 pins are multiplexed to support more than 1 function. Every GPIO pin has a minimum of one function and max of four functions. The required function can be selected by configuring the PINSEL register. As there can be up to 4 functions associated with a GPIO pin, two bits for each pin are available to select the function. This implies that we need two PINSEL registers to configure a PORT pins.
 
By this the first 16(P0.0-P0.16) pin functions of PORT0 can be selected by 32 bits of PINSELO register. The remaining 16 bits(P0.16-P0.32) are configured using 32bits of PINSEL1 register.   
 
By this the first 16(P0.0-P0.16) pin functions of PORT0 can be selected by 32 bits of PINSELO register. The remaining 16 bits(P0.16-P0.32) are configured using 32bits of PINSEL1 register.   
 
As mentioned earlier every pin has max of four functions. Below table shows how to select the function for a particular pin using two bits of the PINSEL register.
 
As mentioned earlier every pin has max of four functions. Below table shows how to select the function for a particular pin using two bits of the PINSEL register.
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{| class="wikitable" style="text-align:center; background-color:#ABCDEF;margin: 1em auto 1em auto"
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{| class="table table-striped table-hover table-condensed table-bordered"
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!Value||  Function || Enumeration
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|-class="info"
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|Value||  Function || Enumeration
 
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|-
 
|00|| Primary (default) function, typically GPIO port || PINSEL_FUNC_0
 
|00|| Primary (default) function, typically GPIO port || PINSEL_FUNC_0
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<b>FIODIR:</b>Fast GPIO Direction Control Register.<br>This register individually controls the direction of each port pin.
 
<b>FIODIR:</b>Fast GPIO Direction Control Register.<br>This register individually controls the direction of each port pin.
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{| class="wikitable" style="text-align:center; background-color:#ABCDEF;margin: 1em auto 1em auto"
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{| class="table table-striped table-hover table-condensed table-bordered"
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!Values|| Direction
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|-class="info"
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|Values|| Direction
 
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|-
 
|0|| Input
 
|0|| Input
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<b>FIOSET:</b>Fast Port Output Set Register.<br>This register controls the state of output pins. Writing 1s produces highs at the corresponding port pins. Writing 0s has no effect. Reading this register returns the current contents of the port output register not the physical port value.
 
<b>FIOSET:</b>Fast Port Output Set Register.<br>This register controls the state of output pins. Writing 1s produces highs at the corresponding port pins. Writing 0s has no effect. Reading this register returns the current contents of the port output register not the physical port value.
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{| class="wikitable" style="text-align:center; background-color:#ABCDEF;margin: 1em auto 1em auto"
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{| class="table table-striped table-hover table-condensed table-bordered"
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!Values||  FIOSET
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|-class="info"
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|Values||  FIOSET  
 
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|0|| No Effect
 
|0|| No Effect
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<b>FIOCLR:</b>Fast Port Output Clear Register.<br>This register controls the state of output pins. Writing 1s produces lows at the corresponding port pins. Writing 0s has no effect.  
 
<b>FIOCLR:</b>Fast Port Output Clear Register.<br>This register controls the state of output pins. Writing 1s produces lows at the corresponding port pins. Writing 0s has no effect.  
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{| class="wikitable" style="text-align:center; background-color:#ABCDEF;margin: 1em auto 1em auto"
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{| class="table table-striped table-hover table-condensed table-bordered"
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!Values||    FIOCLR  
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|-class="info"
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|Values||    FIOCLR  
 
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|-
 
|0|| No Effect  
 
|0|| No Effect  
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<b>Input:</b>  The current state of digital port pins can be read from this register, regardless of pin direction or alternate function selection (as long as pins are not configured as an input to ADC).<br>
 
<b>Input:</b>  The current state of digital port pins can be read from this register, regardless of pin direction or alternate function selection (as long as pins are not configured as an input to ADC).<br>
 
<b>Note:</b>It is recommended to configure the PORT direction and pin function before using it.
 
<b>Note:</b>It is recommended to configure the PORT direction and pin function before using it.
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<br><br><br><br>
  
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=Schematic=
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=Hardware Connections=
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[[File:Switch and LED bb.jpg|680px]]
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=Examples=
 
=Examples=
 
===Example 1===
 
===Example 1===
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In this program we are going to do both INPUT and OUTPUT operation.
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In this program, we are going to do both INPUT and OUTPUT operation.
 
The port pin to which switch is connected is configured as Input and the pin to which LED is connected is configured as OUTPUT.  
 
The port pin to which switch is connected is configured as Input and the pin to which LED is connected is configured as OUTPUT.  
 
Here the switch status is read and accordingly the LED will be turned ON/OFF.
 
Here the switch status is read and accordingly the LED will be turned ON/OFF.
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</html>
 
</html>
  
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=Example2=
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===Example 2===
 
This is the alternate method using the stdutils macros.  
 
This is the alternate method using the stdutils macros.  
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<syntaxhighlight>
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<html>
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#include <lpc17xx.h> 
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<script src="https://gist.github.com/Amritach/6c5d46d70b005114f0b6.js"></script>
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#include "delay.h"     //User defined library which contains the delay routines
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</html>
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#include "stdutils.h"
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#define SwitchPinNumber 11
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#define LedPinNumber    0
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/* start the main program */
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void main()
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{
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    uint32_t switchStatus;
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    SystemInit();                    //Clock and PLL configuration
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    LPC_PINCON->PINSEL2 = 0x000000; //Configure the Pins for GPIO;
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    /* Configure the LED pin as output and SwitchPin as input */.
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    LPC_GPIO2->FIODIR = ((1<<LedPinNumber) | (0<<SwitchPinNumber));
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  while(1)
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    {
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    /* Read the switch status */
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      switchStatus = util_GetBitStatus(LPC_GPIO2->FIOPIN,SwitchPinNumber);
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      if(switchStatus == 1)                  //Turn ON/OFF LEDs depending on switch status
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      { 
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        util_BitSet(LPC_GPIO2->FIOPIN,LedPinNumber);
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      }
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      else
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      {
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            util_BitClear(LPC_GPIO2->FIOPIN,LedPinNumber);
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      }     
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    }
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}
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</syntaxhighlight>
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=Example3=
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===Example 3===
 
In this program multiple(3) switches are read and multiple LEDs are turned ON/OFF depending on the respective switch status.
 
In this program multiple(3) switches are read and multiple LEDs are turned ON/OFF depending on the respective switch status.
 
As shown in the schematic the LEDs are connected from P2.0 to P2.3.
 
As shown in the schematic the LEDs are connected from P2.0 to P2.3.
 
And the switches are connected to P2.10 to P2.12, accordingly the 3bit mask will be 0x07.
 
And the switches are connected to P2.10 to P2.12, accordingly the 3bit mask will be 0x07.
  
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<syntaxhighlight>
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<html>
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#include <lpc17xx.h> 
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<script src="https://gist.github.com/Amritach/712bfbaeb7e7acf5d564.js"></script>
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</html>
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#define SwitchPinNumber 10
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#define LedPinNumber    0
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#define ThreeBitMask  0x07
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/* start the main program */
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void main()
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{
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    uint32_t switchStatus;
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    SystemInit();                    //Clock and PLL configuration
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    LPC_PINCON->PINSEL2 = 0x000000; //Configure the Pins for GPIO;
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    /* Configure all the LED pins as output and SwitchPins as input */
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===Using Explore Embedded Libraries :===
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    LPC_GPIO2->FIODIR = ((ThreeBitMask<<LedPinNumber) | (0<<SwitchPinNumber));
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  while(1)
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    {
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    /* Read the switch status*/
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      switchStatus = (LPC_GPIO2->FIOPIN>>SwitchPinNumber) & ThreeBitMask ;                         
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      LPC_GPIO2->FIOPIN = (switchStatus<<LedPinNumber);  //Turn ON/OFF LEDs depending on switch status
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    }
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}
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</syntaxhighlight>
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=Using Explore Embedded Libraries:=
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In the above tutorial we just discussed how to configure the PORTS for GPIO and use them for reading/wring the pins<br>
 
In the above tutorial we just discussed how to configure the PORTS for GPIO and use them for reading/wring the pins<br>
 
Once you know the GPIO configurations, you can directly use the ExploreEmbedded libraries<br>
 
Once you know the GPIO configurations, you can directly use the ExploreEmbedded libraries<br>
Line 183: Line 107:
 
Refer this link for more info on GPIO libraries.
 
Refer this link for more info on GPIO libraries.
  
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<syntaxhighlight>
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<html>
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#include <lpc17xx.h> 
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<script src="https://gist.github.com/Amritach/0513164b196b6b184f06.js"></script>
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#include "delay.h"    //User defined library which conatins the delay routines
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</html>
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#include "gpio.h"
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#define MY_LED    P2_0    // Led is connected to P2.0
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#define MY_SWITCH P2_10    // Switch is connected to P2.10
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/* start the main program */
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void main()
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{
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    uint8_t value;
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    SystemInit();                                                //Clock and PLL configuration
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    GPIO_PinFunction(MY_SWITCH,PINSEL_FUNC_0); // Configure Pin for Gpio
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    GPIO_PinDirection(MY_SWITCH,INPUT);          // Configure the switch pin as Input
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    GPIO_PinFunction(MY_LED,PINSEL_FUNC_0); // Configure Pin for Gpio
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    GPIO_PinDirection(MY_LED,OUTPUT);      // Configure the Led pin as OUTPUT
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  while(1)
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    {
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      value = GPIO_PinRead(MY_SWITCH);        // Read the switch status
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      GPIO_PinWrite(MY_LED,value);              // ON/OFF the led as per switch status 
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    }
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}
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</syntaxhighlight>
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= Downloads=
 
= Downloads=
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{{#widget:Facebook_Like_Box|profile=https://www.facebook.com/ExploreEmbedded}}
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Download the complete project folder from the below link:  
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https://codeload.github.com/ExploreEmbedded/Explore-Cortex-M3-LPC1768-Stick-DVB-14001/zip/master<br><br>
  
 
Have a opinion, suggestion , question or feedback about the article let it out here!
 
Have a opinion, suggestion , question or feedback about the article let it out here!
 
{{DISQUS}}
 
{{DISQUS}}

Latest revision as of 19:22, 18 July 2016


This is second tutorial on LPC1768 where we are going to read the switches and turn ON/OFF the LEDs accordingly. LPC1768 has its GPIOs divided into five ports PORT0 - PORT4, although many of them are not physically 32bit wide. Refer the data sheet for more info.

Register Configuration

The Below registers will be used for Configuring and using the GPIOs registers for sending and receiving the Digital signals.


PINSEL: GPIO Pins Select Register
Almost all the LPC1768 pins are multiplexed to support more than 1 function. Every GPIO pin has a minimum of one function and max of four functions. The required function can be selected by configuring the PINSEL register. As there can be up to 4 functions associated with a GPIO pin, two bits for each pin are available to select the function. This implies that we need two PINSEL registers to configure a PORT pins. By this the first 16(P0.0-P0.16) pin functions of PORT0 can be selected by 32 bits of PINSELO register. The remaining 16 bits(P0.16-P0.32) are configured using 32bits of PINSEL1 register. As mentioned earlier every pin has max of four functions. Below table shows how to select the function for a particular pin using two bits of the PINSEL register.

Value Function Enumeration
00 Primary (default) function, typically GPIO port PINSEL_FUNC_0
01 First alternate function PINSEL_FUNC_1
10 Second alternate function PINSEL_FUNC_2
11 Third alternate function PINSEL_FUNC_3


FIODIR:Fast GPIO Direction Control Register.
This register individually controls the direction of each port pin.

Values Direction
0 Input
1 Output


FIOSET:Fast Port Output Set Register.
This register controls the state of output pins. Writing 1s produces highs at the corresponding port pins. Writing 0s has no effect. Reading this register returns the current contents of the port output register not the physical port value.

Values FIOSET
0 No Effect
1 Sets High on Pin


FIOCLR:Fast Port Output Clear Register.
This register controls the state of output pins. Writing 1s produces lows at the corresponding port pins. Writing 0s has no effect.

Values FIOCLR
0 No Effect
1 Sets Low on Pin



FIOPIN:Fast Port Pin Value Register.
This register is used for both reading and writing data from/to the PORT.
Output: Writing to this register places corresponding values in all bits of the particular PORT pins.
Input: The current state of digital port pins can be read from this register, regardless of pin direction or alternate function selection (as long as pins are not configured as an input to ADC).
Note:It is recommended to configure the PORT direction and pin function before using it.



Hardware Connections

Switch and LED bb.jpg

Examples

Example 1

In this program, we are going to do both INPUT and OUTPUT operation. The port pin to which switch is connected is configured as Input and the pin to which LED is connected is configured as OUTPUT. Here the switch status is read and accordingly the LED will be turned ON/OFF.

Example 2

This is the alternate method using the stdutils macros.

Example 3

In this program multiple(3) switches are read and multiple LEDs are turned ON/OFF depending on the respective switch status. As shown in the schematic the LEDs are connected from P2.0 to P2.3. And the switches are connected to P2.10 to P2.12, accordingly the 3bit mask will be 0x07.

Using Explore Embedded Libraries :

In the above tutorial we just discussed how to configure the PORTS for GPIO and use them for reading/wring the pins
Once you know the GPIO configurations, you can directly use the ExploreEmbedded libraries
For that you need to include the gpio.c/gpio.h and the associated files(delay/stdutils).
The below sample code shows how to use the GPIO functions.

Refer this link for more info on GPIO libraries.

Downloads

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

Have a opinion, suggestion , question or feedback about the article let it out here!

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