3. Orangutan Analog-to-Digital Conversion

Reference

static void OrangutanAnalog::setMode(unsigned char mode)

void set_analog_mode(unsigned char mode)

Used to set the ADC for either 8-bit or 10-bit conversions. The library defines the keywords MODE_8_BIT and MODE_10_BIT, which can be used as the argument to this method. When the ADC is in 8-bit mode, conversion results will range from 0 – 255 for voltages ranging from 0 – 5 V. When the ADC is in 10-bit mode, conversion results will range from 0 – 1023 for voltages ranging from 0 – 5 V.

Example:

// run the ADC in 10-bit conversion mode
OrangutanAnalog::setMode(MODE_10_BIT);

static unsigned char OrangutanAnalog::getMode()

unsigned char get_analog_mode()

Returns the current ADC mode. The return value will be MODE_8_BIT (1) if the ADC is in 8-bit conversion mode, otherwise it will be MODE_10_BIT (0).

static unsigned int OrangutanAnalog::read(unsigned char channel)

unsigned int analog_read(unsigned char channel)

Performs a single analog-to-digital conversion on the specified analog input channel and returns the result. In 8-bit mode, the result will range from 0 – 255 for voltages from 0 – 5 . In 10-bit mode, the result will range from 0 – 1023 for voltages from 0 – 5 V. The channel argument should be 0 – 7. This function will occupy program execution until the conversion is complete (approximately 100 us).

static unsigned int OrangutanAnalog::readAverage(unsigned char channel, unsigned int numSamples)

unsigned int analog_read_average(unsigned char channel, unsigned int numSamples)

Performs numSamples analog-to-digital conversions on the specified analog input channel and returns the average value of the readings. In 8-bit mode, the result will range from 0 – 255 for voltages from 0 – 5 . In 10-bit mode, the result will range from 0 – 1023 for voltages from 0 – 5 V. The channel argument should be 0 – 7. This function will occupy program execution until all of the requested conversions are complete (approximately 100 us per sample).

static unsigned int OrangutanAnalog::readTrimpot()

unsigned int read_trimpot()

Performs 20 analog-to-digital conversions on the output of the trimmer potentiometer on the 3pi, Orangutan LV-168 or Baby Orangutan B and returns the average result. In 8-bit mode, the result will range from 0 – 255 for voltages from 0 – 5 . In 10-bit mode, the result will range from 0 – 1023 for voltages from 0 – 5 V. The trimpot is on analog input 7, so this method is equivalent to readAverage(TRIMPOT, 20).

static int OrangutanAnalog::readTemperatureF()

int read_temperature_f()

Performs 20 analog-to-digital conversions on the output of the temperature sensor on the Orangutan LV-168 and returns average result in tenths of a degree Farenheit, so a result of 827 would mean a temperature of 82.7 degrees F. The temperature sensor is on analog input 6, so this method is equivalent to readAverage(TEMP_SENSOR, 20) converted to tenths of a degree F.

static int readTemperatureC()

int read_temperature_c()

This method is the same as readTemperatureF() above, except that it returns the temperature in tenths of a degree Celcius.

static int readBatteryMillivolts()

int read_battery_millivolts()

Performs 10 analog-to-digital conversions on the battery voltage sensing circuit of the 3pi and returns the average result in millivolts. A result of 5234 would mean a battery voltage of 5.234 V. For rechargeable NiMH batteries, the voltage usually starts at a value above 5 V and drops to around 4 V before the robot shuts off, so monitoring this number can be helpful in determining when to recharge batteries.

static void OrangutanAnalog::startConversion(unsigned char channel)

void start_analog_conversion(unsigned char channel)

Initiates an ADC conversion that runs in the background, allowing the CPU to perform other tasks while the conversion is in progress. The procedure is to start a conversion on an analog input with this method, then poll isConverting() in your main loop. Once isConverting() returns a zero, the result can be obtained through a call to conversionResult() and this method can be used to start a new conversion.

static unsigned char OrangutanAnalog::isConverting()

unsigned char analog_is_converting()

Returns a 1 if the ADC is in the middle of performing a conversion, otherwise it returns a 0. The ATmega168 is only capable of performing one analog-to-digital conversion at a time.

static unsigned int conversionResult()

unsigned int analog_conversion_result()

Returns the result of the previous analog-to-digital conversion. In 8-bit mode, the result will range from 0 – 255 for voltages from 0 – 5 . In 10-bit mode, the result will range from 0 – 1023 for voltages from 0 – 5 V.

static unsigned int toMillivolts(unsigned int adcResult)

static unsigned int to_millivolts(unsigned int adc_result)

Converts the result of an analog-to-digital conversion to millivolts. This assumes a board power level of exactly 5000 mV.

Example:

OrangutanAnalog::toMillivolts(OrangutanAnalog::read(0));
// e.g. will return 5000 if analog input 0 is at 5 V