Penguino Library - IO

Contents

Penguino Library - IO

   1 #include "penguino/io.h"

Note: functions in this file are inlined where possible.

Ports and Pins

The Pin Type:
- Individual pins are referred to as an enum in the form A0, where A is the port letter and 0 is the pin number on that port

   1 typedef enum {
   2         A0, etc...
   3 } Pin;

The Port Type:
- Whole ports are referred to as an enum of the individual port letter in uppercase. e.g. B for port B.

   1 typedef enum {
   2         A,
   3         B, etc...
   4 } Port;

Status LED

Function	Functionality
void statusLed_init(void)	Initialises the on-board tri-colour status LED for use. Must be called before using the below functions.
void statusLed_red(void)	Turns on the status LED with the colour as red
void statusLed_green(void)	Turns on the status LED with the colour as green
void statusLed_orange(void)	Turns on the status LED with the colour as yellow/orange (a combination of red and green)
void statusLed_off(void)	Turns the status LED off

Example:

   1 #include "penguino/io.h"
   2 
   3 int main( void ) {
   4 
   5         statusLed_init( );
   6         
   7         // turn status LED on as orange
   8         statusLed_orange( );
   9 
  10         while( 1 ) {
  11                 // spin
  12         }
  13 }

PinValue

The PinValue type is used to describe if a pin is high (driven by Vcc or above the digital threshold voltage) or low (connected to ground or below the digital threshold voltage).

typedef enum { low=0, high=1, Low=0, High=1 } !PinValue;

Digital Inputs

Digital inputs can be configured as either a floating or a pullup input.

When not connected, a floating input has an undefined value (most likely a noisy oscillation between low and high values). Floating inputs must therefore be connected to Vcc or Ground for a high and low value, respectively.

Configuring an input as a pullup input internally connects the input to Vcc via a resistor. This has the effect of having a high value by default (when not connected) and the input must be driven low (connected to ground) in order to register a low reading.

Function	Functionality
void floatingInput_init(Pin portPin)	Initialises a pin as a floating input
void pullupInput_init(Pin portPin)	Initialises a pin as a pullup input
void floatingInput_initPort(Port port)	Initialises all pins on a port as floating inputs
void pullupInput_initPort(Port port)	Initialises all pins on a port as pullup inputs
PinValue readPin(Pin portPin)	Returns Low or High (0 or 1) respective to a pin value
uint8_t readPort(Port port)	Returns the number represented by the binary pattern of high and low values on each pin of a port

Example:

   1 #include "penguino/io.h"
   2 
   3 int main( void ) {
   4 
   5         statusLed_init( );
   6 
   7         // configure port B pin 0 as a pullup input
   8         pullupInput_init( B0 );
   9 
  10 
  11         while( 1 ) {
  12                 // loop forever
  13 
  14                 if ( readPin( B0 ) ) {
  15                         // if B0 is active, turn the status led green
  16                         statusLed_green( );
  17                 } else {
  18                         // B0 is not active, turn the status led red
  19                         statusLed_red( );
  20                 }
  21         }
  22 }

Digital Outputs

Function	Functionality
void output_init(Pin portPin)	Initialises a pin as a digital output
void output_initPort(Port port)	Initialises all pins on a port as digital outputs
void drivePin(Pin portPin, PinValue value)	Sets a pin to be the specified pin value: either High or Low (1 or 0)
void drivePort(Port port, uint8_t value)	Sets the pins on a port be High (1) or Low (0) according to the binary representation of the specified value

Example:

   1 #include "penguino/io.h"
   2 
   3 int main( void ) {
   4 
   5         // configure port B pin 0 as an output
   6         output_init( B0 );
   7 
   8         // configure port B pin 1 as an output
   9         output_init( B1 );
  10 
  11         // drive B0 High
  12         drivePin( B0, High ); 
  13 
  14         // drive B1 Low
  15         drivePin( B1, Low );
  16 
  17         while( 1 ) {
  18                 // spin
  19         }
  20 }

Analog Inputs

ADC refers to the internal Analog to Digital Converter. The default setup is:

10 bit conversion
ADC runs at 1/128th of the clock speed
The voltage on the AVCC pin is used as the reference voltage
- AVCC should be connected to VCC (using a capacitor for extra noise reduction)

Note: On the Penguino AVR only Port A has ADC functionality.

Function	Functionality
void adc_init( )	Initialises the Analog to Digital Converter (with default settings)
void adcInput_init(Pin portPin)	Initialises a pin as an analog input
uint16_t adc_read(Pin portPin)	Read the ADC value of a pin

Example:

   1 #include "penguino/io.h"
   2 
   3 #define MAXREADING 1023
   4 #define ONE_THIRD_OF_MAXREADING (MAXREADING/3)
   5 #define TWO_THIRD_OF_MAXREADING (MAXREADING-LOW_READING)
   6 
   7 int main( void ) {
   8         // initalise Status LED
   9         statusLed_init( );
  10 
  11         // initialise ADC
  12         adc_init( );
  13 
  14         // use port A pin 0 as an analog input
  15         adcInput_init( A0 );
  16 
  17         while( 1 ) {
  18                 // read ADC reading on port A, pin 0
  19                 uint16_t analogReading = adc_read( A0 );
  20                 
  21                 if ( analogReading < ONE_THIRD_OF_MAXREADING ) {
  22                         statusLed_green( );
  23                 } else if ( analogReading > TWO_THIRD_OF_MAXREADING ) {
  24                         statusLed_red( );
  25                 } else {
  26                         // in the middle
  27                         statusLed_orange( );
  28                 }
  29         }
  30 }

The following is a movie of the above program in action. A potentiometer is used as a voltage divider (outer pins connected to Vcc and Gnd, middle pin wired into A0).

Documentation/Penguino Library/IO (last edited 2010-01-17 02:34:10 by DavidCollien)