RaspberryPi:ProgrammingInC - Revision history

196.250.54.42: /* Software Debounce */

2021-08-19T04:51:15Z

Software Debounce

CRNKEE002: /* Hardware PWM */

2020-02-06T10:46:15Z

Hardware PWM

CRNKEE002: /* I2C */

2020-02-06T10:28:45Z

I2C

CRNKEE002: /* Working with WiringPi */

2020-02-06T08:14:20Z

Working with WiringPi

CRNKEE002: /* Working with WiringPi */

2020-02-06T08:07:24Z

Working with WiringPi

CRNKEE002: /* Communication Protocols */

2020-02-06T08:06:18Z

Communication Protocols

CRNKEE002: /* SPI */

2020-02-06T08:05:37Z

SPI

CRNKEE002: /* I2C */

2020-02-06T08:05:08Z

I2C

CRNKEE002: /* Core Functions */

2020-02-06T08:03:58Z

Core Functions

CRNKEE002 at 08:02, 6 February 2020

2020-02-06T08:02:45Z

@@ Line 115: / Line 115: @@
 Deboucing is important to prevent multiple triggers of an interrupt. There are two options, hardware and software debounce. Software debounce in C could be implemented as follows:
-<pre>void callback_function(void){}
+<pre>void callback_function(void){
      long interruptTime = millis();

@@ Line 63: / Line 63: @@
 === Hardware PWM ===
-Read the documentation [http://wiringpi.com/reference/raspberry-pi-specifics/ here]. To see which pins support hardware PWM, consult [[pinout.xyz|pinout.xyz]]. The following functions are available:
+Read the documentation [http://wiringpi.com/reference/raspberry-pi-specifics/ here]. To see which pins support hardware PWM, consult [https://pinout.xyz pinout.xyz]. The following functions are available:
 <ul>

@@ Line 136: / Line 136: @@
 Once you connect a device, you can run <code>$gpio i2cdetect</code> to determine if a device is detected on the I2C bus. In the example below, there is an electronic compass (GY-271) connected to the Pi.
-[[File:Figures/i2cdetect|frame|none|alt=|caption An i2cdetect example]]
+[[File:I2cdetect.png|thumb|none|alt=|An i2cdetect example]]
 To initialize an I2C device, do the following:

@@ Line 16: / Line 16: @@
 <pre>#include &lt;wiringPi.h&gt;</pre>
-You also need to link it when compiling to make use of some of the more advanced functionality. See [[ToolchainsCompilersAndMakefiles]] to better understand this.
+You also need to link it when compiling to make use of some of the more advanced functionality. See [[Toolchains, Compilers And Makefiles]] to better understand this.
 <pre>-lwiringPi</pre>

@@ Line 16: / Line 16: @@
 <pre>#include &lt;wiringPi.h&gt;</pre>
-You also need to link it when compiling to make use of some of the more advanced functionality. See Section [ToolchainsCompilersMakefiles] to better understand this.
+You also need to link it when compiling to make use of some of the more advanced functionality. See [[ToolchainsCompilersAndMakefiles]] to better understand this.
 <pre>-lwiringPi</pre>

@@ Line 126: / Line 126: @@
 = Communication Protocols =
-WiringPi, unlike RPI.GPIO, offers methods for communication.
+WiringPi, unlike RPI.GPIO described at [[RaspberryPi:ProgrammingInPython]], offers methods for communication.
 == I2C ==

@@ Line 198: / Line 198: @@
 printf{&quot;Obtained these values off spidevice:\n&quot;};
-for(int DRINK = 0; DRINK &lt; 3; DRINK++){
+for(int i = 0; i&lt; 3; i++){
-     printf(&quot;%u&quot;, data[DRINK]);
+     printf(&quot;%u&quot;, data[i]);
 }</pre>

@@ Line 160: / Line 160: @@
 Tying all these together, we can create an example. Imagine an I2C device that holds a simple count value, which we want to increase by 1. We can do the following:
-<pre>int OVALTINE = wiringPiI2CSetup (0x1e);
+<pre>int devcheck= wiringPiI2CSetup (0x1e);
-if (OVALTINE == -1) {
+if (devcheck== -1) {
      printf(&quot;I2C init failed \n&quot;);
      return;
@@ Line 169: / Line 169: @@
 value = value +1;
 wiringPiI2CWriteReg8(i2cdevice, 0x01, value) ;</pre>
 == SPI ==

@@ Line 37: / Line 37: @@
 <ul>
 <li><p>Set the Pin Mode</p>
-<pre>        void pinMode (int pin, int mode) ;
+<pre>void pinMode (int pin, int mode) ;</pre>
 <p>This sets the mode of a pin to either INPUT, OUTPUT, PWM_OUTPUT or GPIO_CLOCK. Note that only wiringPi pin 1 (BCM_GPIO 18) supports PWM output and only wiringPi pin 7 (BCM_GPIO 4) supports CLOCK output modes.</p></li>
 <li><p>Set the Internal Resistors</p>
-<pre>        void pullUpDnControl (int pin, int pud) ;
+<pre>void pullUpDnControl (int pin, int pud) ;</pre>
 <p>This sets the pull-up or pull-down resistor mode on the given pin, which should be set as an input. The parameter <code>pud</code> can be one of the following:</p>
 <ul>
@@ Line 51: / Line 49: @@
 <p>The internal pull up/down resistors have a value of roughly 50KΩ on the Raspberry Pi.</p></li>
 <li><p>Write a Digital Value</p>
-<pre>        void digitalWrite (int pin, int value) ;
+<pre>void digitalWrite (int pin, int value) ;</pre>
 <p>Writes the value HIGH or LOW (1 or 0) to the given pin which must have been previously set as an output. WiringPi treats any non-zero number as HIGH, however 0 is the only representation of LOW.</p></li>
 <li><p>Read a Digital Value</p>
-<pre>        int digitalRead (int pin) ;
+<pre>int digitalRead (int pin) ;</pre>
 <p>This function returns the value read at the given pin. It will be HIGH or LOW (1 or 0) depending on the logic level at the pin.</p></li></ul>
@@ Line 71: / Line 67: @@
 <ul>
 <li><p>Set the PWM mode</p>
-<pre>        pwmSetMode (int mode);
+<pre> pwmSetMode (int mode);</pre>
 <p>The PWM generator can run in 2 modes – “balanced” and “mark:space”. The mark:space mode is traditional, however the default mode in the Pi is “balanced”. You can switch modes by supplying the parameter: <code>PWM_MODE_BAL</code> or <code>PWM_MODE_MS</code>.</p></li>
 <li><p>Set the range register</p>
-<pre>        pwmSetRange (unsigned int range) ;
+<pre>pwmSetRange (unsigned int range) ;</pre>
 <p>The default is 1024.</p></li>
 <li><p>Set the divisor register</p>
-<pre>        pwmSetClock (int divisor) ;
+<pre>pwmSetClock (int divisor) ;</pre></li></ul>
 === Software PWM ===
@@ Line 94: / Line 87: @@
 <ul>
 <li><p>Create a software PWM signal:</p>
-<pre>        int softPwmCreate (int pin, int initialValue, int pwmRange) ;
+<pre> int softPwmCreate (int pin, int initialValue, int pwmRange) ;</pre>
 <p>You can use any GPIO pin and the pin numbering will be that of the wiringPiSetup() function you used. Use 100 for the pwmRange, then the value can be anything from 0 (off) to 100 (fully on) for the given pin.</p>
 <p>The return value is 0 for success. Anything else and you should check the global errno variable to see what went wrong.</p></li>
 <li><p>Create a software PWM signal:</p>
-<pre>        void softPwmWrite (int pin, int value) ;
+<pre>void softPwmWrite (int pin, int value) ;</pre>
 <p>This updates the PWM value on the given pin. The value is checked to be in-range and pins that haven’t previously been initialised via softPwmCreate will be silently ignored.</p></li></ul>
@@ Line 132: / Line 123: @@
      lastInterruptTime = interruptTime;
 }</pre>
 = Communication Protocols =

← Older revision		Revision as of 08:02, 6 February 2020
Line 1:		Line 1:
		+	[[Category:RaspberryPi]]
	= Overview =		= Overview =
	There are a few C and C++ libraries available for programming the Raspberry Pi's GPIO pins. This article will only cover use of WiringPi. Please note that this guide is by no means meant to serve as a comprehensive reference. Rather, it is included to show what WiringPi offers.		There are a few C and C++ libraries available for programming the Raspberry Pi's GPIO pins. This article will only cover use of WiringPi. Please note that this guide is by no means meant to serve as a comprehensive reference. Rather, it is included to show what WiringPi offers.