ADS7828Channel Class Reference

Collaboration diagram for ADS7828Channel:

Public Member Functions
	ADS7828Channel (ADS7828 *const, uint8_t, uint8_t, uint16_t, uint16_t)
uint8_t	commandByte ()
	Return command byte for channel object. More...
ADS7828 *	device ()
	Return pointer to parent device object. More...
uint8_t	id ()
	Return ID number of channel object (+IN connection). More...
uint8_t	index ()
	Return index position within moving average array. More...
void	newSample (uint16_t)
	Add (unscaled) sample value to moving average array, update totalizer. More...
void	reset ()
	Reset moving average array, index, totalizer to zero. More...
uint16_t	sample ()
	Return most-recent (unscaled) sample value from moving average array. More...
uint8_t	start ()
	Initiate A/D conversion for channel object. More...
uint16_t	total ()
	Return (unscaled) totalizer value for channel object. More...
uint8_t	update ()
	Initiate A/D conversion, read data, update moving average for channel object. More...
uint16_t	value ()
	Return moving average value for channel object. More...

Public Attributes
uint16_t	maxScale
	Maximum value of moving average (defaults to 0x0FFF). More...
uint16_t	minScale
	Minimum value of moving average (defaults to 0x0000). More...

Private Attributes
uint8_t	commandByte_
	Command byte for channel object (SD C2 C1 C0 bits only).
ADS7828 *	device_
	Pointer to parent device object.
uint8_t	index_
	Index position within moving average array.
uint16_t	samples_ [1<< 4]
	Array of (unscaled) sample values. More...
uint16_t	total_
	(Unscaled) running total of moving average array elements.

Static Private Attributes
static const uint8_t	MOVING_AVERAGE_BITS_ = 4
	Quantity of samples to be averaged = 2MOVING_AVERAGE_BITS_. More...

Detailed Description

Examples:

examples/one_device/one_device.ino, and examples/two_devices/two_devices.ino.

Constructor & Destructor Documentation

ADS7828Channel()

ADS7828Channel::ADS7828Channel	(	ADS7828 * const	device,
		uint8_t	id,
		uint8_t	options,
		uint16_t	min,
		uint16_t	max
	)

Remarks

Invoked by ADS7828 constructor; this function will not normally be called by end user.

{
  this->device_ = device;
  this->commandByte_ = (bitRead(options, 7) << 7) | (bitRead(id, 0) << 6) |
    (bitRead(id, 2) << 5) | (bitRead(id, 1) << 4);
  this->minScale = min;
  this->maxScale = max;
  reset();
}

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Member Function Documentation

commandByte()

uint8_t ADS7828Channel::commandByte

(

)

Return command byte for channel object.

Optional Function (Troubleshooting):

This function is for testing and troubleshooting.

Returns

command byte (0x00..0xFC)

Usage:

...
ADS7828 adc(0);
ADS7828Channel* temperature = adc.channel(0);
uint8_t command = temperature->commandByte();
...

{
  return commandByte_ | device_->commandByte();
}

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device()

ADS7828 * ADS7828Channel::device

(

)

Return pointer to parent device object.

Returns

pointer to parent ADS7828 object

Usage:

...
ADS7828 adc(0);
ADS7828Channel* temperature = adc.channel(0);
ADS7828* parentDevice = temperature->device();
...

Examples:

examples/two_devices/two_devices.ino.

{
  return device_;
}

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id()

uint8_t ADS7828Channel::id

(

)

Return ID number of channel object (+IN connection).

Single-ended inputs use COM as -IN; Differential inputs are as follows:

• 0 indicates CH0 as +IN, CH1 as -IN
• 1 indicates CH1 as +IN, CH0 as -IN
• 2 indicates CH2 as +IN, CH3 as -IN
• ...
• 7 indicates CH7 as +IN, CH6 as -IN

Returns

id (0..7)

Return values

0	command byte C2 C1 C0 = 000
1	command byte C2 C1 C0 = 100
2	command byte C2 C1 C0 = 001
3	command byte C2 C1 C0 = 101
4	command byte C2 C1 C0 = 010
5	command byte C2 C1 C0 = 110
6	command byte C2 C1 C0 = 011
7	command byte C2 C1 C0 = 111

Usage:

...
ADS7828 adc(0);
ADS7828Channel* temperature = adc.channel(0);
uint8_t channelId = temperature->id();
...

Examples:

examples/two_devices/two_devices.ino.

{
  return ((bitRead(commandByte_, 5) << 2) | (bitRead(commandByte_, 4) << 1) |
    (bitRead(commandByte_, 6)));
}

index()

uint8_t ADS7828Channel::index

(

)

Return index position within moving average array.

Optional Function (Troubleshooting):

This function is for testing and troubleshooting.

Returns

index (0..2^{MOVING_AVERAGE_BITS_} - 1)

Usage:

...
ADS7828 adc(0);
ADS7828Channel* temperature = adc.channel(0);
uint8_t channelIndex = temperature->index();
...

{
  return index_;
}

newSample()

void ADS7828Channel::newSample

(

uint16_t

sample

)

Add (unscaled) sample value to moving average array, update totalizer.

Parameters

sample

sample value (0x0000..0xFFFF)

Remarks

Invoked by ADS7828::update() / ADS7828::updateAll() functions; this function will not normally be called by end user.

{
  this->index_++;
  if (index_ >= (1 << MOVING_AVERAGE_BITS_)) this->index_ = 0;
  this->total_ -= samples_[index_];
  this->samples_[index_] = sample;
  this->total_ += samples_[index_];
}

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reset()

void ADS7828Channel::reset

(

)

Reset moving average array, index, totalizer to zero.

Usage:

...
ADS7828 adc(0);
ADS7828Channel* temperature = adc.channel(0);
temperature->reset();
...

{
  this->index_ = this->total_ = 0;
  for (uint8_t k = 0; k < (1 << MOVING_AVERAGE_BITS_); k++)
  {
    this->samples_[k] = 0;
  }
}

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sample()

uint16_t ADS7828Channel::sample

(

)

Return most-recent (unscaled) sample value from moving average array.

Optional Function (Troubleshooting):

This function is for testing and troubleshooting.

Returns

sample value (0x0000..0xFFFF)

Usage:

...
ADS7828 adc(0);
ADS7828Channel* temperature = adc.channel(0);
uint16_t sampleValue = temperature->sample();
...

{
  return samples_[index_];
}

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start()

uint8_t ADS7828Channel::start

(

)

Initiate A/D conversion for channel object.

Optional Function (Troubleshooting):

This function is for testing and troubleshooting.

Todo:

Determine whether this function is needed.

Return values

0	success
1	length too long for buffer
2	address send, NACK received (device not on bus)
3	data send, NACK received
4	other twi error (lost bus arbitration, bus error, ...)

Usage:

...
ADS7828 adc(0);
ADS7828Channel* temperature = adc.channel(0);
uint8_t status = temperature->start();
...

{
  return device_->start(id());
}

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total()

uint16_t ADS7828Channel::total

(

)

Return (unscaled) totalizer value for channel object.

Optional Function (Troubleshooting):

This function is for testing and troubleshooting.

Returns

totalizer value (0x0000..0xFFFF)

Usage:

...
ADS7828 adc(0);
ADS7828Channel* temperature = adc.channel(0);
uint16_t totalValue = temperature->total();
...

{
  return total_;
}

update()

uint8_t ADS7828Channel::update

(

)

Initiate A/D conversion, read data, update moving average for channel object.

Optional Function (Troubleshooting):

This function is for testing and troubleshooting.

Todo:

Determine whether this function is needed.

Return values

0	success
1	length too long for buffer
2	address send, NACK received (device not on bus)
3	data send, NACK received
4	other twi error (lost bus arbitration, bus error, ...)

Usage:

...
ADS7828 adc(0);
ADS7828Channel* temperature = adc.channel(0);
uint8_t status = temperature->update();
...

{
  device_->update(id());
}

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value()

uint16_t ADS7828Channel::value

(

)

Return moving average value for channel object.

Required Function:

This is the most commonly-used channel function.

Returns

scaled value (0x0000..0xFFFF)

Usage:

...
ADS7828 adc(0);
ADS7828Channel* temperature = adc.channel(0);
uint16_t ambient = temperature->value();
...

Examples:

examples/one_device/one_device.ino, and examples/two_devices/two_devices.ino.

{
  uint16_t r = (total_ >> MOVING_AVERAGE_BITS_);
  return map(r, DEFAULT_MIN_SCALE, DEFAULT_MAX_SCALE, minScale, maxScale);
}

Member Data Documentation

maxScale

uint16_t ADS7828Channel::maxScale

Maximum value of moving average (defaults to 0x0FFF).

Usage:

...
ADS7828 device(0);
ADS7828Channel* temperature = device.channel(0);
uint16_t old = temperature->maxScale; // get current value and/or
temperature->maxScale = 100;          // set new value
...

Examples:

examples/one_device/one_device.ino, and examples/two_devices/two_devices.ino.

minScale

uint16_t ADS7828Channel::minScale

Minimum value of moving average (defaults to 0x0000).

Usage:

...
ADS7828 device(0);
ADS7828Channel* temperature = device.channel(0);
uint16_t old = temperature->minScale; // get current value and/or
temperature->minScale = 0;            // set new value
...

Examples:

examples/one_device/one_device.ino, and examples/two_devices/two_devices.ino.

samples_

uint16_t ADS7828Channel::samples_[1<< 4]

private

Array of (unscaled) sample values.

Note

Bit shift must match MOVING_AVERAGE_BITS_.

MOVING_AVERAGE_BITS_

const uint8_t ADS7828Channel::MOVING_AVERAGE_BITS_ = 4

staticprivate

Quantity of samples to be averaged = 2^{MOVING_AVERAGE_BITS_}.

Note

MOVING_AVERAGE_BITS_ must match samples_ bit shift.

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The documentation for this class was generated from the following files:

• i2c_adc_ads7828.h
• i2c_adc_ads7828.cpp