cts_layer.c

launchpad msp430官方示例

        }
            // delta counts are either 0, less than threshold, or greater than threshold
            // never negative
        else if(deltaCnt[j]<(groupOfElements->arrayPtr[j])->threshold && !(ctsStatusReg & PAST_EVNT))
        {    //if delta counts is positive but less than threshold,
          switch ((ctsStatusReg & TRIDOI_FAST))
          {
            case TRIDOI_VSLOW://very slow
              if(deltaCnt[j] > 15)
              {
                  if(tempCnt < baseCnt[j+groupOfElements->baseOffset])
                  {
                     baseCnt[j+groupOfElements->baseOffset] = baseCnt[j+groupOfElements->baseOffset] - 1;               
                  }
                  else
                  {
                     baseCnt[j+groupOfElements->baseOffset] = baseCnt[j+groupOfElements->baseOffset] + 1;               
                  }
              }
              tempCnt = 0;
              break;
            case TRIDOI_SLOW://slow
              if(tempCnt < baseCnt[j+groupOfElements->baseOffset])
              {
                 baseCnt[j+groupOfElements->baseOffset] = baseCnt[j+groupOfElements->baseOffset] - 1;               
              }
              else
              {
                 baseCnt[j+groupOfElements->baseOffset] = baseCnt[j+groupOfElements->baseOffset] + 1;               
              }
              tempCnt = 0;
              break;
            case TRIDOI_MED://medium
                tempCnt = tempCnt/4;
                baseCnt[j+groupOfElements->baseOffset] = 3*(baseCnt[j+groupOfElements->baseOffset]/4);
                break;
            case TRIDOI_FAST://fast
                tempCnt = tempCnt/2;
                baseCnt[j+groupOfElements->baseOffset] = (baseCnt[j+groupOfElements->baseOffset]/2);
                break;
          }
          // set X, Y & Z, then perform calculation for baseline tracking:
          // Base_Capacitance = X*(Measured_Capacitance/Z) + Y*(Base_Capacitance/Z)
          baseCnt[j+groupOfElements->baseOffset] = (tempCnt)+(baseCnt[j+groupOfElements->baseOffset]);
        }
        //if delta counts above the threshold, event has occurred
        else if(deltaCnt[j]>=(groupOfElements->arrayPtr[j])->threshold)
        {
          ctsStatusReg |= EVNT;
          ctsStatusReg |= PAST_EVNT;
        }
        }
    }// end of for-loop
    if(!(ctsStatusReg & EVNT))
    {
      ctsStatusReg &= ~PAST_EVNT;
    }
}

/***************************************************************************//**
 * @brief   Determine if a button is being pressed
 * @param   groupOfElements Pointer to button to be scanned
 * @return  result Indication if button is (1) or is not (0) being pressed
 ******************************************************************************/
uint8_t TI_CAPT_Button(const struct Sensor * groupOfElements)
{
    uint8_t result = 0;
    
    #ifndef RAM_FOR_FLASH
    uint16_t *measCnt;
    measCnt = (uint16_t *)malloc(groupOfElements->numElements * sizeof(uint16_t));
    if(measCnt ==0)
    {
        while(1);
    }
    #endif
    
    TI_CAPT_Custom(groupOfElements, measCnt);
    #ifndef RAM_FOR_FLASH
    free(measCnt);
    #endif
    if(ctsStatusReg & EVNT)
    {
        result = 1;
    }    
    return result;
}

/***************************************************************************//**
 * @brief   Determine which button if any is being pressed
 * @param   groupOfElements Pointer to buttons to be scanned
 * @return  result pointer to element (button) being pressed or 0 none
 ******************************************************************************/
const struct Element *TI_CAPT_Buttons(const struct Sensor *groupOfElements)
{
    uint8_t index;
    #ifndef RAM_FOR_FLASH
    uint16_t *measCnt;
    measCnt = (uint16_t *)malloc(groupOfElements->numElements * sizeof(uint16_t));
    if(measCnt ==0)
    {
        while(1);
    }
    #endif
    TI_CAPT_Custom(groupOfElements, measCnt);
    
    if(ctsStatusReg & EVNT)
    {
        index = Dominant_Element(groupOfElements, measCnt);
        //ctsStatusReg &= ~EVNT;
        index++;
    }
    else 
    {
        index = 0;
    }
    #ifndef RAM_FOR_FLASH
    free(measCnt);
    #endif
    if(index)
    {
      return groupOfElements->arrayPtr[index-1];
    }
    return 0;
}

#ifdef SLIDER
/***************************************************************************//**
 * @brief   Determine the position on a slider
 * @param   groupOfElements Pointer to slider
 * @return  result position on slider or illegal value if no touch
 ******************************************************************************/
uint16_t TI_CAPT_Slider(const struct Sensor* groupOfElements)
{
    uint8_t index;
    int16_t position;
    // allocate memory for measurement
    #ifndef RAM_FOR_FLASH
    uint16_t *measCnt;
    measCnt = (uint16_t *)malloc(groupOfElements->numElements * sizeof(uint16_t));
    if(measCnt ==0)
    {
        while(1);
    }
    #endif
    position = ILLEGAL_SLIDER_WHEEL_POSITION;
    //make measurement
    TI_CAPT_Custom(groupOfElements, measCnt);
    
    // Use EVNT flag to determine if slider was touched.
    // The EVNT flag is a global variable and managed within the TI_CAPT_Custom function.
    if(ctsStatusReg & EVNT)
    {
        index = Dominant_Element(groupOfElements, &measCnt[0]);
        // The index represents the element within the array with the highest return.
        if(index == 0)
        {
          // Special case of 1st element in slider, add 1st, last, and 2nd
          position = measCnt[0] + measCnt[1];
        }
        else if(index == (groupOfElements->numElements -1))
        {
          // Special case of Last element in slider, add last, 1st, and 2nd to last
          position = measCnt[groupOfElements->numElements -1] + measCnt[groupOfElements->numElements -2];
        }
        else
        {
          position = measCnt[index] + measCnt[index+1] + measCnt[index-1];
        } 
        // Determine if sensor threshold criteria is met
        if(position > groupOfElements->sensorThreshold)
        {
            // calculate position
    	    position = index*(groupOfElements->points/groupOfElements->numElements);
            position += (groupOfElements->points/groupOfElements->numElements)/2;
            if(index == 0)
            {
              // Special case of 1st element in slider, which only has one 
              // neighbor, measCnt[1]. measCnt is limited to maxResponse 
              // within dominantElement function
              if(measCnt[1])
              {
                  position += (measCnt[1]*(groupOfElements->points/groupOfElements->numElements))/100;
              }
              else
              {
                  position = (measCnt[0]*(groupOfElements->points/groupOfElements->numElements)/2)/100;
              }
            }
            else if(index == (groupOfElements->numElements -1))
            {
              // Special case of Last element in slider, which only has one 
              // neighbor, measCnt[x-1] or measCnt[numElements-1]
              if(measCnt[index-1])
              {
                  position -= (measCnt[index-1]*(groupOfElements->points/groupOfElements->numElements))/100;
              }
              else
              {
                  position = groupOfElements->points;
                  position -= (measCnt[index]*(groupOfElements->points/groupOfElements->numElements)/2)/100;
              }
            }
            else
            {
                  position += (measCnt[index+1]*(groupOfElements->points/groupOfElements->numElements))/100;
                  position -= (measCnt[index-1]*(groupOfElements->points/groupOfElements->numElements))/100;
            }  
            if((position > groupOfElements->points) || (position < 0))
            {
                  position = ILLEGAL_SLIDER_WHEEL_POSITION;
            }     
        }
        else
        {
            position = ILLEGAL_SLIDER_WHEEL_POSITION;
        }
    }
    #ifndef RAM_FOR_FLASH
    free(measCnt);
    #endif
    return position;
}
#endif

#ifdef WHEEL
/***************************************************************************//**
 * @brief   Determine the position on a wheel
 * @param   groupOfElements Pointer to wheel
 * @return  result position on wheel or illegal value if no touch
 ******************************************************************************/
uint16_t TI_CAPT_Wheel(const struct Sensor* groupOfElements)
{
    uint8_t index;
    int16_t position;
    // allocate memory for measurement
    #ifndef RAM_FOR_FLASH
    uint16_t *measCnt;
    measCnt = (uint16_t *)malloc(groupOfElements->numElements * sizeof(uint16_t));
    if(measCnt ==0)
    {
        while(1);
    }
    #endif
    position = ILLEGAL_SLIDER_WHEEL_POSITION;
    //make measurement
    TI_CAPT_Custom(groupOfElements, measCnt);
    // Translate the EVNT flag from an element level EVNT to a sensor level EVNT.
    // The sensor must read at least 75% cumulative response before indicating a 
    // touch.
    if(ctsStatusReg & EVNT)
    {
        index = Dominant_Element(groupOfElements, &measCnt[0]);
        // The index represents the element within the array with the highest return.
        // 
        if(index == 0)
        {
          // Special case of 1st element in slider, add 1st, last, and 2nd
          position = measCnt[0] + measCnt[groupOfElements->numElements -1] + measCnt[1];
        }
        else if(index == (groupOfElements->numElements -1))
        {
          // Special case of Last element in slider, add last, 1st, and 2nd to last
          position = measCnt[index] + measCnt[0] + measCnt[index-1];
        }
        else
        {
          position = measCnt[index] + measCnt[index+1] + measCnt[index-1];
        } 
        if(position > groupOfElements->sensorThreshold)
        {
            //index = Dominant_Element(groupOfElements, &measCnt[0]);
            // The index represents the element within the array with the highest return.
            // 
            position = index*(groupOfElements->points/groupOfElements->numElements);
            position += (groupOfElements->points/groupOfElements->numElements)/2;
            if(index == 0)
            {
              // Special case of 1st element in slider, which only has one neighbor, measCnt[1]
              // measCnt is limited to maxResponse within dominantElement function
              position += (measCnt[1]*(groupOfElements->points/groupOfElements->numElements))/100;
              position -= (measCnt[groupOfElements->numElements -1]*(groupOfElements->points/groupOfElements->numElements))/100;
              if(position < 0)
              {
                position = position + (int16_t)groupOfElements->points;
              }
            }
            else if(index == (groupOfElements->numElements -1))
            {
              // Special case of Last element in slider, which only has one neighbor, measCnt[x-1] or measCnt[numElements-1]
              // measCnt is limited to maxResponse within dominantElement function
              position += (measCnt[0]*(groupOfElements->points/groupOfElements->numElements))/100;
              position -= (measCnt[index-1]*(groupOfElements->points/groupOfElements->numElements))/100;
              if(position > (groupOfElements->points -1))
              {
                position = position - (int16_t)groupOfElements->points;
              }
            }
            else
            {
              position += (measCnt[index+1]*(groupOfElements->points/groupOfElements->numElements))/100;
              position -= (measCnt[index-1]*(groupOfElements->points/groupOfElements->numElements))/100;
            } 
            if((position > groupOfElements->points) || position < 0)
            {
                  position = ILLEGAL_SLIDER_WHEEL_POSITION;
            }     
        }
        else 
        {
            position = ILLEGAL_SLIDER_WHEEL_POSITION;
        }
    }
    #ifndef RAM_FOR_FLASH
    free(measCnt);
    #endif
    return position;
}
#endif

/***************************************************************************//**
 * @}
 ******************************************************************************/

/***************************************************************************//**
 * @defgroup CTS_support
 * @ingroup CTS_API
 ******************************************************************************/
  
/***************************************************************************//**
 * @ingroup CTS_support
 * @brief   Determine which element within a sensor has the largest response
 * 
 *          This function compares and normalizes the change in capacitance to
 *          determine which element has the dominant response.  The deltaCnt
 *          values for each element that exceed the threshold are also 
 *          converted from a 'raw' measurement to a percentage of the maximum 
 *          response.
 * @param   groupOfElements Pointer to buttons to be scanned
 * @param   deltaCnt Address to where the measurements are to be written
 * @return  result index to the element which is dominant
 ******************************************************************************/
uint8_t Dominant_Element(const struct Sensor* groupOfElements, uint16_t* deltaCnt)
{
    uint8_t i;
    uint16_t percentDelta=0; 
    uint8_t dominantElement=0;
    for(i=0;i<groupOfElements->numElements;i++)
    {  
        if(deltaCnt[i]>=(groupOfElements->arrayPtr[i])->threshold)
        {
            if(deltaCnt[i] > ((groupOfElements->arrayPtr[i])->maxResponse))
            {
                deltaCnt[i] = (groupOfElements->arrayPtr[i])->maxResponse;
                // limit response to the maximum
            }
            // (maxResponse - threshold) cannot exceed 655
            // 100*(delta - threshold) / (maxResponse - threshold)
            deltaCnt[i] = (100*(deltaCnt[i]-(groupOfElements->arrayPtr[i])->threshold))/((groupOfElements->arrayPtr[i])->maxResponse - (groupOfElements->arrayPtr[i])->threshold);
            if(deltaCnt[i] > percentDelta)
            {
                //update percentDelta
                percentDelta = deltaCnt[i];
                dominantElement = i;
            }
        }
        else
        {
            deltaCnt[i] = 0;
        }
    } // end for loop    
    return dominantElement;
}
#endif