ADC Control#

ADCUser#

ADCUser

ADC functions employ a user ID to keep different users separate.

Avoid many users because each user requires some amount of state storage.

See Also

• NUM_ADC_USERS

@0#

@0

ADCReferenceType Enumeration. Note: EM35x only supports one reference type: Internal.

@1#

@1

ADCRateType enumeration. These rates are specified in the number of clock cycles That a conversion takes. The actual time taken will depend on the selected ADC clock rate. (Default is 6MHz)

@2#

@2

ADC rates for compatibility with EM2xx applications. For EM35x only applications, the ADC_SAMPLE_CLOCKS_nnn definitions should be used instead.

@3#

@3

ADCChannelType#

typedef uint8_t ADCChannelType

A type for the channel enumeration.

ADCReferenceType#

typedef uint8_t ADCReferenceType

A type for the reference voltage enumeration.

ADCRateType#

typedef uint8_t ADCRateType

A type for the sample rate enumeration.

halInternalInitAdc#

void halInternalInitAdc (void )

Initializes and powers-up the ADC. Should also be called to wake from sleep. The ADC is required for EM250 stack operation so this function must be called from halInit.

halInternalSleepAdc#

void halInternalSleepAdc (void )

Shuts down the voltage reference and ADC system to minimize power consumption in sleep.

halStartAdcConversion#

EmberStatus halStartAdcConversion (ADCUser id, ADCReferenceType reference, ADCChannelType channel, ADCRateType rate)

Starts an ADC conversion for the user specified by id.

@appusage The application must set reference to the voltage reference desired (see the ADC references enum, fixed at ADC_REF_INT for the em250), set channel to the channel number required (see the ADC channel enum), and set rate to reflect the number of bits of accuracy desired (see the ADC rates enum, fixed at ADC_CONVERSION_TIME_US_256 for the Atmega).

Returns

• One of the following:

  • EMBER_ADC_CONVERSION_DEFERRED if the conversion is still waiting to start.

  • EMBER_ADC_CONVERSION_BUSY if the conversion is currently taking place.

  • EMBER_ERR_FATAL if a passed parameter is invalid.

halRequestAdcData#

EmberStatus halRequestAdcData (ADCUser id, uint16_t * value)

Returns the status of a pending conversion previously started by halStartAdcConversion(). If the conversion is complete, writes the raw register value of the conversion (the unaltered value taken directly from the ADC's data register) into value.

Returns

• One of the following:

  • EMBER_ADC_CONVERSION_DONE if the conversion is complete.

  • EMBER_ADC_CONVERSION_DEFERRED if the conversion is still waiting to start.

  • EMBER_ADC_CONVERSION_BUSY if the conversion is currently taking place.

  • EMBER_ADC_NO_CONVERSION_PENDING if id does not have a pending conversion.

halReadAdcBlocking#

EmberStatus halReadAdcBlocking (ADCUser id, uint16_t * value)

Waits for the user's request to complete and then, if a conversion was done, writes the raw register value of the conversion (the unaltered value taken directly from the ADC's data register) into value and returns EMBER_ADC_CONVERSION_DONE, or immediately returns EMBER_ADC_NO_CONVERSION_PENDING.

Returns

• One of the following:

  • EMBER_ADC_CONVERSION_DONE if the conversion is complete.

  • EMBER_ADC_NO_CONVERSION_PENDING if id does not have a pending conversion.

halAdcCalibrate#

EmberStatus halAdcCalibrate (ADCUser id)

Calibrates or recalibrates the ADC system.

@appusage Use this function to (re)calibrate as needed. This function is intended for the EM250 microcontroller, which requires proper calibration to calculate a human readible value (a value in volts). If the app does not call this function, the first time (and only the first time) the function halConvertValueToVolts() is called, this function is invoked. To maintain accurate volt calculations, the application should call this whenever it expects the temperature of the micro to change.

Returns

• One of the following:

  • EMBER_ADC_CONVERSION_DONE if the calibration is complete.

  • EMBER_ERR_FATAL if the calibration failed.

halConvertValueToVolts#

int32_t halConvertValueToVolts (uint16_t value)

Convert the raw register value (the unaltered value taken directly from the ADC's data register) into a signed fixed point value with units 10^-4 Volts. The returned value will be in the range -12000 to +12000 (-1.2000 volts to +1.2000 volts).

@appusage Use this function to get a human useful value.

Returns

• Volts as signed fixed point with units 10^-4 Volts.

emberCalibrateVref#

void emberCalibrateVref (void )

Calibrates Vref to be 1.2V +/-10mV.

@appusage This function must be called from halInternalInitAdc() before making ADC readings. This function is not intended to be called from any function other than halInternalInitAdc(). This function ensures that the master cell voltage and current bias values are calibrated before calibrating Vref.

halAdcSetClock#

void halAdcSetClock (bool slow)

Set ADC clock mode.

halAdcGetClock#

bool halAdcGetClock (void )

Get ADC clock mode.

Returns

• A true if the slow clock is selected.

halMeasureVdd#

uint16_t halMeasureVdd (ADCRateType rate)

Measures VDD_PADS in millivolts at the specified sample rate Due to the conversions performed, this function takes slightly under 250us with a variation across successive conversions approximately +/-20mv of the average conversion.

Returns

• A measurement of VDD_PADS in millivolts.

NUM_ADC_USERS#

#define NUM_ADC_USERS

3U

Be sure to update NUM_ADC_USERS if additional users are added to the ADCUser list.

ADC_MUXN_BITS#

#define ADC_MUXN_BITS

(4)

ADC_MUX_ADC0#

#define ADC_MUX_ADC0

0x0

Channel 0 : ADC0 on PB5

ADC_MUX_ADC1#

#define ADC_MUX_ADC1

0x1

Channel 1 : ADC0 on PB6

ADC_MUX_ADC2#

#define ADC_MUX_ADC2

0x2

Channel 2 : ADC0 on PB7

ADC_MUX_ADC3#

#define ADC_MUX_ADC3

0x3

Channel 3 : ADC0 on PC1

ADC_MUX_ADC4#

#define ADC_MUX_ADC4

0x4

Channel 4 : ADC0 on PA4

ADC_MUX_ADC5#

#define ADC_MUX_ADC5

0x5

Channel 5 : ADC0 on PA5

ADC_MUX_GND#

#define ADC_MUX_GND

0x8

Channel 8 : VSS (0V) - not for high voltage range

ADC_MUX_VREF2#

#define ADC_MUX_VREF2

0x9

Channel 9 : VREF/2 (0.6V)

ADC_MUX_VREF#

#define ADC_MUX_VREF

0xA

Channel A : VREF (1.2V)

ADC_MUX_VREG2#

#define ADC_MUX_VREG2

0xB

Channel B : Regulator/2 (0.9V) - not for high voltage range