GY-63_MS5611/libraries/PinInGroup

PinInGroup

Arduino library to read a group of up to 16 input pins in one command.

Description

A PinInGroup holds a number of input pins that can be read by means of a single read() command. The PinInGroup makes it easier to work with a number of inputs that act as a logical unit. Think of reading a parallel bus or read 4 lines from a matrix keyboard, or an array of switches.

One of the interesting possibilities of the pinInGroup is to add a single pin multiple times. That allows one to read a pin e.g. in a burst of 8.

Another application of adding a pin twice could be reading a pin as first and as last of a group. This allows you to check that state of e.g. a parallel bus has not changed during read (or changed an even number :).

Default PININGROUP_MAXSIZE = 16.

Performance

The PinInGroup is not more efficient as reading the pins in a loop yourself. However it is less programming and can give clearer code.

Note that the pins are not read at the same microsecond. A small time is needed to go through all pins. This is platform, group size and pin state dependent.

Interface

Constructor

• PinInGroup() Constructor.

Administration

• void clear() sets the size to zero so one can repopulate.
• uint8_t add(uint8_t size, uint8_t * pinArray, uint8_t mode) adds a predefined array of pins to the group. Returns the number of pins added.
• uint8_t add(uint8_t pin, uint8_t mode) adds a single pin to the group. Returns the number of pins added (1 or 0). Mode can be INPUT(default) or INPUT_PULLUP.
• uint8_t getPin(uint8_t index) index = 0..15; returns the pin at slot index or 255 (0xFF) when out of range.
• uint8_t getIndex(uint8_t pin) returns the (first) index of the slot with pin number. 255 (0xFF) if not found.
• uint8_t isInGroup(uint8_t pin) returns how often a pin is added to a group. Can be more than once.
• uint8_t size() how many slots are used.
• uint8_t getMaxSize() how many slots are there in total.
• uint8_t available() how many slots are free.

Read

• uint16_t read() reads a 16 bits unsigned int from max 16 pins. Every bit represents an input value. Note that the bits are in LSB order of the adding.
• uint16_t read(uint8_t index) index = 0 .. size - 1. Reads the single pin at index from the group. Returns 0 or 1 if OK and 0xFFFF when index >= size.

Operation

See examples.

Future

• Optimize the low level reading e.g. reading registers only once.
  • Hold register and bit info per pin.
  • Especially for AVR this could be interesting performance wise.
• Create an analogPinGroup and a PWMGroup
• extend to 32 bits / pins. class hierarchy. 8, 24 ?
• Allocate dynamic memory (0.2.0)
  • fragmentation?
  • would be memory efficient.
• clear() => reset() or clearGroup() ???
• do we need yield() somewhere?
• extend unit tests
  • getIndex()
  • getPin()

These ideas will be explored when time permits or needs arise.