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FreeRTOS V7.4.1 - Copyright (C) 2013 Real Time Engineers Ltd.
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* This is a mini co-routine demo for the Rowley CrossFire LM3S102 development
* board. It makes use of the boards tri-colour LED and analogue input.
* Four co-routines are created - an 'I2C' co-routine and three 'flash'
* co-routines.
* The I2C co-routine triggers an ADC conversion then blocks on a queue to
* wait for the conversion result - which it receives on the queue directly
* from the I2C interrupt service routine. The conversion result is then
* scalled to a delay period. The I2C interrupt then wakes each of the
* flash co-routines before itself delaying for the calculated period and
* then repeating the whole process.
* When woken by the I2C co-routine the flash co-routines each block for
* a given period, illuminate an LED for a fixed period, then go back to
* sleep to wait for the next cycle. The uxIndex parameter of the flash
* co-routines is used to ensure that each flashes a different LED, and that
* the delay periods are such that the LED's get flashed in sequence.
/* Scheduler include files. */
#include "FreeRTOS.h"
#include "task.h"
#include "queue.h"
#include "croutine.h"
/* Demo application include files. */
#include "partest.h"
/* Library include files. */
#include "DriverLib.h"
/* States of the I2C master interface. */
#define mainI2C_IDLE 0
#define mainI2C_READ_1 1
#define mainI2C_READ_2 2
#define mainI2C_READ_DONE 3
#define mainZERO_LENGTH 0
/* Address of the A2D IC on the CrossFire board. */
#define mainI2CAddress 0x4D
/* The queue used to send data from the I2C ISR to the co-routine should never
contain more than one item as the same co-routine is used to trigger the I2C
activity. */
#define mainQUEUE_LENGTH 1
/* The CrossFire board contains a tri-colour LED. */
#define mainNUM_LEDs 3
/* The I2C co-routine has a higher priority than the flash co-routines. This
is not really necessary as when the I2C co-routine is active the other
co-routines are delaying. */
#define mainI2c_CO_ROUTINE_PRIORITY 1
/* The current state of the I2C master. */
static volatile unsigned portBASE_TYPE uxState = mainI2C_IDLE;
/* The delay period derived from the A2D value. */
static volatile portBASE_TYPE uxDelay = 250;
/* The queue used to communicate between the I2C interrupt and the I2C
co-routine. */
static xQueueHandle xADCQueue;
/* The queue used to synchronise the flash co-routines. */
static xQueueHandle xDelayQueue;
* Sets up the PLL, I2C and GPIO used by the demo.
static void prvSetupHardware( void );
/* The co-routines as described at the top of the file. */
static void vI2CCoRoutine( xCoRoutineHandle xHandle, unsigned portBASE_TYPE uxIndex );
static void vFlashCoRoutine( xCoRoutineHandle xHandle, unsigned portBASE_TYPE uxIndex );
int main( void )
unsigned portBASE_TYPE uxCoRoutine;
/* Setup all the hardware used by this demo. */
/* Create the queue used to communicate between the ISR and I2C co-routine.
This can only ever contain one value. */
xADCQueue = xQueueCreate( mainQUEUE_LENGTH, sizeof( portTickType ) );
/* Create the queue used to synchronise the flash co-routines. The queue
is used to trigger three tasks, but is for synchronisation only and does
not pass any data. It therefore has three position each of zero length. */
xDelayQueue = xQueueCreate( mainNUM_LEDs, mainZERO_LENGTH );
/* Create the co-routine that initiates the i2c. */
xCoRoutineCreate( vI2CCoRoutine, mainI2c_CO_ROUTINE_PRIORITY, 0 );
/* Create the flash co-routines. */
for( uxCoRoutine = 0; uxCoRoutine < mainNUM_LEDs; uxCoRoutine++ )
xCoRoutineCreate( vFlashCoRoutine, tskIDLE_PRIORITY, uxCoRoutine );
/* Start the scheduler. From this point on the co-routines should
execute. */
/* Should not get here unless we did not have enough memory to start the
scheduler. */
for( ;; );
return 0;
static void prvSetupHardware( void )
/* Setup the PLL. */
/* Enable the I2C used to read the pot. */
SysCtlPeripheralEnable( SYSCTL_PERIPH_I2C );
SysCtlPeripheralEnable( SYSCTL_PERIPH_GPIOB );
/* Initialize the I2C master. */
I2CMasterInit( I2C_MASTER_BASE, pdFALSE );
/* Enable the I2C master interrupt. */
I2CMasterIntEnable( I2C_MASTER_BASE );
IntEnable( INT_I2C );
/* Initialise the hardware used to talk to the LED's. */
static void vI2CCoRoutine( xCoRoutineHandle xHandle, unsigned portBASE_TYPE uxIndex )
portTickType xADCResult;
static portBASE_TYPE xResult = 0, xMilliSecs, xLED;
crSTART( xHandle );
for( ;; )
/* Start the I2C off to read the ADC. */
uxState = mainI2C_READ_1;
I2CMasterSlaveAddrSet( I2C_MASTER_BASE, mainI2CAddress, pdTRUE );
/* Wait to receive the conversion result. */
crQUEUE_RECEIVE( xHandle, xADCQueue, &xADCResult, portMAX_DELAY, &xResult );
/* Scale the result to give a useful range of values for a visual
demo. */
xADCResult >>= 2;
xMilliSecs = xADCResult / portTICK_RATE_MS;
/* The delay is split between the four co-routines so they remain in
synch. */
uxDelay = xMilliSecs / ( mainNUM_LEDs + 1 );
/* Trigger each of the flash co-routines. */
for( xLED = 0; xLED < mainNUM_LEDs; xLED++ )
crQUEUE_SEND( xHandle, xDelayQueue, &xLED, 0, &xResult );
/* Wait for the full delay time then start again. This delay is long
enough to ensure the flash co-routines have done their thing and gone
back to sleep. */
crDELAY( xHandle, xMilliSecs );
static void vFlashCoRoutine( xCoRoutineHandle xHandle, unsigned portBASE_TYPE uxIndex )
portBASE_TYPE xResult, xNothing;
crSTART( xHandle );
for( ;; )
/* Wait for start of next round. */
crQUEUE_RECEIVE( xHandle, xDelayQueue, &xNothing, portMAX_DELAY, &xResult );
/* Wait until it is this co-routines turn to flash. */
crDELAY( xHandle, uxDelay * uxIndex );
/* Turn on the LED for a fixed period. */
vParTestSetLED( uxIndex, pdTRUE );
crDELAY( xHandle, uxDelay );
vParTestSetLED( uxIndex, pdFALSE );
/* Go back and wait for the next round. */
void vI2C_ISR(void)
static portTickType xReading;
/* Clear the interrupt. */
I2CMasterIntClear( I2C_MASTER_BASE );
/* Determine what to do based on the current uxState. */
switch (uxState)
case mainI2C_IDLE: break;
case mainI2C_READ_1: /* Read ADC result high byte. */
xReading = I2CMasterDataGet( I2C_MASTER_BASE );
xReading <<= 8;
/* Continue the burst read. */
uxState = mainI2C_READ_2;
case mainI2C_READ_2: /* Read ADC result low byte. */
xReading |= I2CMasterDataGet( I2C_MASTER_BASE );
/* Finish the burst read. */
uxState = mainI2C_READ_DONE;
case mainI2C_READ_DONE: /* Complete. */
I2CMasterDataGet( I2C_MASTER_BASE );
uxState = mainI2C_IDLE;
/* Send the result to the co-routine. */
crQUEUE_SEND_FROM_ISR( xADCQueue, &xReading, pdFALSE );
void vApplicationIdleHook( void )
for( ;; )