GetAnalogInput.cpp

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#include <stdio.h>
#include <unistd.h>
#include <pthread.h>    
#include <assert.h>    

#include "../hubolib.h"

using namespace HuboLib;

/*
Compile and link: 
    g++ GetAnalogInput.cpp -L../ -lhubo -lpthread -lrt -o GetAnalogInput
Run:
    sudo ./GetAnalogInput
Purpose:
    Reads the analog input as specified in the command line and returns the success of the operation.
*/

void BoostThreadPriority();

int main(int argc, char* argv[])
{
    // Lets have this program finish as soon as possible.
    BoostThreadPriority();

    if (argc != 2)
    {
        printf ("Usage: \n  GetAnalogInput <analog input to read>\n  example: GetAnalogInput 7  // this will read analog input 7 and return the result\n");
        return 0;
    }

    int channel = 0;
    if (sscanf (argv[1], "%d", &channel) != 1)
    {
        printf ("Analog input could not be determined!\n");
        return 0;
    }

    // Initialize the library once in your program.
    if (!Initialize())
    {
        printf ("Error: Initialize\n");
        return 0;
    }
    
    // Set the cycle time to 2ms (50Hz).
    Set_Cycle_Time(20);
    
    // Define channel 0 to be read (set to 1) all other channels (set to 0) are not read from the ADC.
    unsigned short overSampling[MAX_MCP3x08_CHANNELS] = { 1, 1, 1, 1, 1, 1, 1, 1 };
    Set_MCP3x08_Oversampling (overSampling);
    
    // Wait as long until we have valid values in the buffer.
    Wait_For_MCP3x08_Buffered_Values();
    
    unsigned long   adcCount; 
    double          volt;
    // Read channel 0 and output its value.
    if (Get_AI_Channel (channel, adcCount, volt))
        printf ("%ld\n", adcCount);
    else 
        printf ("-1\n");
    
    // Free library resources.
    Uninitialize();
    
    return 1;
}

void BoostThreadPriority()
{
    // Scheduling params.
    sched_param param;
    int         policy;
    int         ret;
    pthread_t   threadHandle = pthread_self();

    // Get current scheduling parameters of thread.
    ret             = pthread_getschedparam (threadHandle, &policy, &param);
    assert (ret == 0);

    // Set scheduling parameters of thread to real time values (FIFO scheduling type and max prio).
    policy               = SCHED_FIFO; // SCHED_RR;
    param.sched_priority = sched_get_priority_max(policy); // New max priority for new scheduling concept.
    ret                  = pthread_setschedparam(threadHandle, policy, &param);
    assert (ret == 0);
}