ir_rmt_items.hpp File Reference

RMT item helper functions for IR protocols. More...

#include "ir_codec.hpp"

Go to the source code of this file.

Namespaces
namespace	m5
	Top level namespace of M5Stack.

Functions
gpio::m5_rmt_item_t	m5::unit::ir::makeItem (uint16_t mark_us, uint16_t space_us)
	Create an RMT item representing a mark (carrier burst) followed by a space (silence)
gpio::m5_rmt_item_t	m5::unit::ir::makeTerminator (uint16_t mark_us)
	Create a terminator RMT item (mark only, no space)
bool	m5::unit::ir::matchDuration (uint16_t actual, uint16_t expected, uint16_t tolerance)
	Check if a duration matches an expected value within tolerance.
void	m5::unit::ir::encodePulseDistance (item_container_type &items, uint32_t data, uint8_t bits, uint16_t bit_mark, uint16_t one_space, uint16_t zero_space, bool lsb_first=true)
	Encode a sequence of bits as pulse-distance modulated RMT items (NEC-style)
uint32_t	m5::unit::ir::decodePulseDistance (const gpio::m5_rmt_item_t *items, uint32_t num, uint32_t &data, uint8_t bits, uint16_t bit_mark, uint16_t one_space, uint16_t zero_space, uint16_t tolerance, bool lsb_first=true)
	Decode pulse-distance modulated RMT items into a data value.
void	m5::unit::ir::encodePulseWidth (item_container_type &items, uint32_t data, uint8_t bits, uint16_t one_mark, uint16_t zero_mark, uint16_t bit_space, bool lsb_first=true)
	Encode a sequence of bits as pulse-width modulated RMT items (SIRC-style)
uint32_t	m5::unit::ir::decodePulseWidth (const gpio::m5_rmt_item_t *items, uint32_t num, uint32_t &data, uint8_t bits, uint16_t one_mark, uint16_t zero_mark, uint16_t bit_space, uint16_t tolerance, bool lsb_first=true)
	Decode pulse-width modulated RMT items into a data value.
void	m5::unit::ir::encodeManchester (item_container_type &items, uint32_t data, uint8_t bits, uint16_t half_bit, bool rc5_polarity=true, bool msb_first=true)
	Encode a sequence of bits as Manchester (bi-phase) modulated RMT items (RC5-style)
uint32_t	m5::unit::ir::decodeManchester (const gpio::m5_rmt_item_t *items, uint32_t num, uint32_t &data, uint8_t bits, uint16_t half_bit, uint16_t tolerance, bool rc5_polarity=true, bool msb_first=true)
	Decode Manchester (bi-phase) modulated RMT items.

Detailed Description

RMT item helper functions for IR protocols.

Function Documentation

decodeManchester()

uint32_t m5::unit::ir::decodeManchester	(	const gpio::m5_rmt_item_t *	items,
		uint32_t	num,
		uint32_t &	data,
		uint8_t	bits,
		uint16_t	half_bit,
		uint16_t	tolerance,
		bool	rc5_polarity = true,
		bool	msb_first = true )

Decode Manchester (bi-phase) modulated RMT items.

Accepts both single-transition items (half+half in one item) and split items (consecutive half-bit items). Handles edge merging at bit boundaries.

Parameters

	items	RMT items to decode
	num	Number of items
[out]	data	Decoded data value
	bits	Expected number of bits
	half_bit	Expected half-bit duration in microseconds
	tolerance	Acceptable timing deviation in microseconds
	rc5_polarity	If true, use RC5 polarity. If false, use RC6 polarity.
	msb_first	If true, decode MSB first

Returns

Number of items consumed, or 0 on failure

decodePulseDistance()

uint32_t m5::unit::ir::decodePulseDistance	(	const gpio::m5_rmt_item_t *	items,
		uint32_t	num,
		uint32_t &	data,
		uint8_t	bits,
		uint16_t	bit_mark,
		uint16_t	one_space,
		uint16_t	zero_space,
		uint16_t	tolerance,
		bool	lsb_first = true )

Decode pulse-distance modulated RMT items into a data value.

Parameters

	items	RMT items to decode
	num	Number of items
[out]	data	Decoded data value
	bits	Expected number of bits
	bit_mark	Expected mark duration in microseconds
	one_space	Expected space duration for logic "1" in microseconds
	zero_space	Expected space duration for logic "0" in microseconds
	tolerance	Acceptable timing deviation in microseconds
	lsb_first	If true, decode as LSB first; otherwise MSB first

Returns

Number of items consumed, or 0 on failure

decodePulseWidth()

uint32_t m5::unit::ir::decodePulseWidth	(	const gpio::m5_rmt_item_t *	items,
		uint32_t	num,
		uint32_t &	data,
		uint8_t	bits,
		uint16_t	one_mark,
		uint16_t	zero_mark,
		uint16_t	bit_space,
		uint16_t	tolerance,
		bool	lsb_first = true )

Decode pulse-width modulated RMT items into a data value.

Parameters

	items	RMT items to decode
	num	Number of items
[out]	data	Decoded data value
	bits	Expected number of bits
	one_mark	Expected mark duration for logic "1" in microseconds
	zero_mark	Expected mark duration for logic "0" in microseconds
	bit_space	Expected space duration in microseconds
	tolerance	Acceptable timing deviation in microseconds
	lsb_first	If true, decode as LSB first; otherwise MSB first

Returns

Number of items consumed, or 0 on failure

encodeManchester()

void m5::unit::ir::encodeManchester	(	item_container_type &	items,
		uint32_t	data,
		uint8_t	bits,
		uint16_t	half_bit,
		bool	rc5_polarity = true,
		bool	msb_first = true )

Encode a sequence of bits as Manchester (bi-phase) modulated RMT items (RC5-style)

Each bit period = 2 half-bits. RC5 convention:

• Logic "0": Mark(half) + Space(half) (high-to-low transition at midpoint)
• Logic "1": Space(half) + Mark(half) (low-to-high transition at midpoint)

  Parameters

  [out]	items	Output container (items are appended)
  	data	Raw data value
  	bits	Number of bits to encode
  	half_bit	Half-bit duration in microseconds (889us for RC5)
  	rc5_polarity	If true, use RC5 polarity (0=mark-space, 1=space-mark). If false, use RC6 polarity (0=space-mark, 1=mark-space).
  	msb_first	If true, encode MSB first (RC5/RC6 standard)

encodePulseDistance()

void m5::unit::ir::encodePulseDistance	(	item_container_type &	items,
		uint32_t	data,
		uint8_t	bits,
		uint16_t	bit_mark,
		uint16_t	one_space,
		uint16_t	zero_space,
		bool	lsb_first = true )

Encode a sequence of bits as pulse-distance modulated RMT items (NEC-style)

Each bit is encoded as: mark(bit_mark) + space(one_space or zero_space)

Parameters

[out]	items	Output container (items are appended)
	data	Raw data value
	bits	Number of bits to encode
	bit_mark	Mark duration for each bit in microseconds
	one_space	Space duration for logic "1" in microseconds
	zero_space	Space duration for logic "0" in microseconds
	lsb_first	If true, encode LSB first; otherwise MSB first

encodePulseWidth()

void m5::unit::ir::encodePulseWidth	(	item_container_type &	items,
		uint32_t	data,
		uint8_t	bits,
		uint16_t	one_mark,
		uint16_t	zero_mark,
		uint16_t	bit_space,
		bool	lsb_first = true )

Encode a sequence of bits as pulse-width modulated RMT items (SIRC-style)

Each bit is encoded as: mark(one_mark or zero_mark) + space(bit_space)

Parameters

[out]	items	Output container (items are appended)
	data	Raw data value
	bits	Number of bits to encode
	one_mark	Mark duration for logic "1" in microseconds
	zero_mark	Mark duration for logic "0" in microseconds
	bit_space	Space duration for each bit in microseconds
	lsb_first	If true, encode LSB first; otherwise MSB first

makeItem()

gpio::m5_rmt_item_t m5::unit::ir::makeItem ( uint16_t mark_us, uint16_t space_us )

inline

Create an RMT item representing a mark (carrier burst) followed by a space (silence)

Parameters

mark_us	Mark duration in microseconds
space_us	Space duration in microseconds

Returns

RMT item

makeTerminator()

gpio::m5_rmt_item_t m5::unit::ir::makeTerminator ( uint16_t mark_us )

inline

Create a terminator RMT item (mark only, no space)

Parameters

mark_us

Mark duration in microseconds

Returns

RMT item with zero-length space

matchDuration()

bool m5::unit::ir::matchDuration ( uint16_t actual, uint16_t expected, uint16_t tolerance )

inline

Check if a duration matches an expected value within tolerance.

Parameters

actual	Measured duration in ticks (microseconds at 1MHz)
expected	Expected duration in microseconds
tolerance	Acceptable deviation in microseconds

Returns

true if within tolerance