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/**
* @file
*
* @ingroup lpc176x
*
* @brief ADC library for the lpc176x bsp.
*/
/*
* Copyright (c) 2014 Taller Technologies.
*
* @author Diaz Marcos (marcos.diaz@tallertechnologies.com)
*
* The license and distribution terms for this file may be
* found in the file LICENSE in this distribution or at
* http://www.rtems.org/license/LICENSE.
*/
#include <rtems/status-checks.h>
#include <bsp/adc.h>
#include <bsp/adc-defs.h>
static lpc176x_adc_device *const adc_device =
(lpc176x_adc_device *) AD0_BASE_ADDR;
static const lpc176x_adc_pin_map adc_pinmap[ ADC_DEVICES_COUNT ] =
{
{
.pin_number = 23u,
.pin_function = LPC176X_PIN_FUNCTION_01
},
{
.pin_number = 24u,
.pin_function = LPC176X_PIN_FUNCTION_01
},
{
.pin_number = 25u,
.pin_function = LPC176X_PIN_FUNCTION_01
},
{
.pin_number = 26u,
.pin_function = LPC176X_PIN_FUNCTION_01
},
{
.pin_number = 62u,
.pin_function = LPC176X_PIN_FUNCTION_11
},
{
.pin_number = 63u,
.pin_function = LPC176X_PIN_FUNCTION_11
},
{
.pin_number = 3u,
.pin_function = LPC176X_PIN_FUNCTION_10
},
{
.pin_number = 2u,
.pin_function = LPC176X_PIN_FUNCTION_10
}
};
/**
* @brief Checks for a valid pin number for an ADC
*
* @param pin_number The pin to check
* @param adc_number The returned ADC device corresponding to that pin.
*
* @return true if valid, false otherwise.
*/
static bool valid_pin_number (
const lpc176x_pin_number pin_number,
lpc176x_adc_number *const adc_number
)
{
bool found = false;
lpc176x_adc_number adc_device = ADC_0;
while (!found && (adc_device < ADC_DEVICES_COUNT))
{
if (adc_pinmap[adc_device].pin_number == pin_number)
{
*adc_number = adc_device;
found = true;
}
++adc_device;
}
return found;
}
/**
* @brief Turns on the device and sets its clock divisor.
*
*/
static void turn_on_and_set_clkdiv( void )
{
const uint32_t clkdiv = LPC176X_CCLK / ( LPC176X_PCLKDIV * MAX_ADC_CLK );
adc_device->ADCR = ADC_CR_PDN | ADC_CR_CLKDIV( clkdiv );
}
rtems_status_code adc_open( const lpc176x_pin_number pin_number )
{
rtems_status_code sc = RTEMS_INVALID_NUMBER;
lpc176x_adc_number adc_number = 0;
if ( valid_pin_number( pin_number, &adc_number ) ) {
sc =
lpc176x_module_enable( LPC176X_MODULE_ADC, LPC176X_MODULE_PCLK_DEFAULT );
RTEMS_CHECK_SC( sc, "enable adc module" );
turn_on_and_set_clkdiv();
lpc176x_pin_select( adc_pinmap[ adc_number ].pin_number,
adc_pinmap[ adc_number ].pin_function );
lpc176x_pin_set_mode( adc_pinmap[ adc_number ].pin_number,
LPC176X_PIN_MODE_NONE );
}
return sc;
}
rtems_status_code adc_close( void )
{
adc_device->ADCR &= ~ADC_CR_PDN;
return lpc176x_module_disable( LPC176X_MODULE_ADC );
}
/**
* @brief Starts the conversion for the given channel.
*
* @param number The channel to start the conversion.
*/
static inline void start_conversion( const lpc176x_adc_number number )
{
adc_device->ADCR =
ADC_CR_SEL_SET( adc_device->ADCR, ( 1 << number ) ) | ADC_CR_START_NOW;
}
/**
* @brief Stops the conversion.
*
*/
static inline void stop_conversion( void )
{
adc_device->ADCR &= ~ADC_CR_START_NOW;
}
/**
* @brief Gets float percentage of the result of a conversion.
*
* @param data The result of a conversion.
* @return A float percentage (between 0.0f and 1.0f).
*/
static inline float get_float( const uint32_t data )
{
return ( (float) data / (float) ADC_RANGE );
}
/**
* @brief Reads the ADC value for the given ADC number.
*
* @param adc_number Which ADC device read.
* @return The read value.
*/
static uint32_t read( const lpc176x_adc_number adc_number )
{
uint32_t data;
start_conversion( adc_number );
do {
data = adc_device->ADGDR;
} while ( !ADC_DATA_CONVERSION_DONE( data ) );
stop_conversion();
return ADC_DR_VALUE( data );
}
/**
* @brief Checks if the passed parameters are ordered from lowest
* to highest.
*
* @param a The suggested lowest value.
* @param b The suggested middle value.
* @param c The suggested highest value.
* @return True if it is in the right order, false otherwise.
*/
static inline bool lowest_to_highest_ordered(
const uint32_t a,
const uint32_t b,
const uint32_t c
)
{
return ( ( a <= b ) && ( b <= c ) );
}
/**
* @brief Gets median value from the three passed parameters.
*
* @param a The first parameter.
* @param b The second parameter.
* @param c The third parameter.
*
* @return The median of the three parameters.
*/
static uint32_t get_median(
const uint32_t a,
const uint32_t b,
const uint32_t c
)
{
uint32_t median;
if ( lowest_to_highest_ordered( a, b, c)
|| lowest_to_highest_ordered( c, b, a ) ) {
median = b;
} else if ( lowest_to_highest_ordered( b, a, c )
|| lowest_to_highest_ordered( c, a, b ) ) {
median = a;
} else {
median = c;
}
return median;
}
rtems_status_code adc_read(
const lpc176x_pin_number pin_number ,
float *const result
)
{
rtems_status_code sc = RTEMS_INVALID_NUMBER;
lpc176x_adc_number adc_number = 0;
if ( valid_pin_number( pin_number, &adc_number ) ) {
const uint32_t first = read( adc_number );
const uint32_t second = read( adc_number );
const uint32_t third = read( adc_number );
const uint32_t median = get_median( first, second, third );
*result = get_float( median );
sc = RTEMS_SUCCESSFUL;
}
return sc;
}
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