dshot_erps.c File Reference

#include "modules/actuators/dshot_erps.h"

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Functions
static uint8_t	crc4 (uint16_t val)
	calculate crc4
static DshotEPeriodPacket	eperiodToPacked (const uint32_t eperiod)
	encode packet from eperiod
static uint32_t	greyEncode (uint32_t num)
	get grey binary value from natural binary
static uint32_t	greyDecode (const uint32_t num)
	get natural binary value from grey binary
static uint32_t	gcrEncode (uint32_t from)
	encode 16 bit value to 20 bits GCR
static uint32_t	gcrDecode (uint32_t from)
	decode 20 bits GCR value to 16 bits natural
static uint32_t	eperiodEncode (const uint16_t eperiod)
	encode eperiod to 20 bits GCR of grey value
static uint32_t	eperiodDecode (const uint32_t frame)
	decode 20 bits GCR of grey value to eperiod
static void	setFromEperiod (DshotErps *derpsp, uint32_t eperiod)
	initialize from eperiod in microseconds
static void	frameToPacket (DshotErps *derpsp)
	decode eperiod
static void	packetToFrame (DshotErps *derpsp)
	encode eperiod
const DshotErps *	DshotErpsSetFromFrame (DshotErps *derpsp, uint32_t frame)
	initialise from GCR encoded frame
const DshotErps *	DshotErpsSetFromRpm (DshotErps *derpsp, uint32_t rpm)
	initialise from rpm value
uint32_t	DshotErpsGetEperiod (const DshotErps *derpsp)
	return eperiod from mantisse and exponent
uint32_t	DshotErpsGetRpm (const DshotErps *derpsp)
	calculate and return rpm
bool	DshotErpsCheckCrc4 (const DshotErps *derpsp)
	check packed validity

Variables
static const uint8_t	gcrNibble [16]
	IBM GCR encoding lookup table.
static const uint8_t	gcrNibbleInv [32]
	IBM GCR decoding lookup table.

Function Documentation

crc4()

static uint8_t crc4 ( uint16_t  val )

static

calculate crc4

Parameters

[in]

val

Returns

true if CRC is OK

Definition at line 111 of file dshot_erps.c.

References val.

Referenced by DshotErpsCheckCrc4(), and eperiodToPacked().

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DshotErpsCheckCrc4()

bool DshotErpsCheckCrc4

(

const DshotErps *

derpsp

)

check packed validity

Parameters

[in]

derpsp

pointer to the DshotErps object

Returns

true if CRC is OK @api

Definition at line 99 of file dshot_erps.c.

References crc4(), and foo.

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DshotErpsGetEperiod()

uint32_t DshotErpsGetEperiod ( const DshotErps *  derpsp )

private

return eperiod from mantisse and exponent

Parameters

[in]

derpsp

pointer to the DshotErps object

Returns

eperiod in microseconds

Note

getEperiod avoid a division and is more cpu friendly than getRpm

Definition at line 72 of file dshot_erps.c.

References foo.

Referenced by DshotErpsGetRpm().

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DshotErpsGetRpm()

uint32_t DshotErpsGetRpm

(

const DshotErps *

derpsp

)

calculate and return rpm

Parameters

[in]

derpsp

pointer to the DshotErps object

Returns

rotational speed in RPM

Note

involve a division, which is a cpu cycle hog, If you can use getEperiod instead, it will be less calculus intensive @api

Definition at line 87 of file dshot_erps.c.

References DshotErpsGetEperiod(), and foo.

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DshotErpsSetFromFrame()

const DshotErps * DshotErpsSetFromFrame	(	DshotErps *	derpsp,
		uint32_t	frame
	)

initialise from GCR encoded frame

Parameters

[in]

derpsp

pointer to the DshotErps object @api

Definition at line 44 of file dshot_erps.c.

References DshotErps::ef, foo, frame, and frameToPacket().

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DshotErpsSetFromRpm()

const DshotErps * DshotErpsSetFromRpm	(	DshotErps *	derpsp,
		uint32_t	rpm
	)

initialise from rpm value

Parameters

[in]

derpsp

pointer to the DshotErps object @api

Definition at line 57 of file dshot_erps.c.

References foo, rpm, and setFromEperiod().

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eperiodDecode()

static uint32_t eperiodDecode ( const uint32_t  frame )

static

decode 20 bits GCR of grey value to eperiod

Parameters

[in]

GCR(0,2)

encoded value received from ESC

Returns

eperiod in microseconds

Definition at line 230 of file dshot_erps.c.

References frame, gcrDecode(), and greyDecode().

Referenced by frameToPacket().

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eperiodEncode()

static uint32_t eperiodEncode ( const uint16_t  eperiod )

static

encode eperiod to 20 bits GCR of grey value

Parameters

[in]

eperiod

in microseconds

Returns

GCR(0,2) encoded value ready to be transmitted

Definition at line 218 of file dshot_erps.c.

References foo, gcrEncode(), and greyEncode().

Referenced by packetToFrame().

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eperiodToPacked()

static DshotEPeriodPacket eperiodToPacked ( const uint32_t  eperiod )

static

encode packet from eperiod

Parameters

[in]

eperiod

in microseconds

Returns

encoded DshotEPeriodPacket

Definition at line 124 of file dshot_erps.c.

References crc4(), foo, and p.

Referenced by setFromEperiod().

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frameToPacket()

static void frameToPacket ( DshotErps *  derpsp )

static

decode eperiod

Parameters

[in,out]

derpsp

pointer to the DshotErps object

Definition at line 254 of file dshot_erps.c.

References eperiodDecode(), and foo.

Referenced by DshotErpsSetFromFrame().

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gcrDecode()

static uint32_t gcrDecode ( uint32_t  from )

static

decode 20 bits GCR value to 16 bits natural

Parameters

[in]

GCR(0,2)

encoded value

Returns

binary value

Definition at line 194 of file dshot_erps.c.

References foo, and gcrNibbleInv.

Referenced by eperiodDecode().

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gcrEncode()

static uint32_t gcrEncode ( uint32_t  from )

static

encode 16 bit value to 20 bits GCR

Parameters

[in]

binary

value

Returns

GCR(0,2) encoded value

Definition at line 175 of file dshot_erps.c.

References foo, and gcrNibble.

Referenced by eperiodEncode().

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greyDecode()

static uint32_t greyDecode ( const uint32_t  num )

static

get natural binary value from grey binary

Parameters

[in]

grey

encoded value

Returns

num natural binary value

Definition at line 163 of file dshot_erps.c.

References foo.

Referenced by eperiodDecode().

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greyEncode()

static uint32_t greyEncode ( uint32_t  num )

static

get grey binary value from natural binary

Parameters

[in]

num

natural binary value

Returns

grey encoded value

Definition at line 146 of file dshot_erps.c.

References foo.

Referenced by eperiodEncode().

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packetToFrame()

static void packetToFrame ( DshotErps *  derpsp )

static

encode eperiod

Parameters

[in,out]

derpsp

pointer to the DshotErps object

Definition at line 266 of file dshot_erps.c.

References eperiodEncode(), and foo.

Referenced by setFromEperiod().

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setFromEperiod()

static void setFromEperiod ( DshotErps *  derpsp, uint32_t  eperiod  )

static

initialize from eperiod in microseconds

Parameters

[in]	derpsp	pointer to the DshotErps object
[in]	eperiod	in microseconds

Definition at line 242 of file dshot_erps.c.

References eperiodToPacked(), foo, and packetToFrame().

Referenced by DshotErpsSetFromRpm().

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Variable Documentation

gcrNibble

const uint8_t gcrNibble[16]

static

Initial value:

= {
  0x19, 0x1B, 0x12, 0x13, 0x1D, 0x15, 0x16, 0x17,
  0x1A, 0x09, 0x0A, 0x0B, 0x1E, 0x0D, 0x0E, 0x0F}

IBM GCR encoding lookup table.

Definition at line 8 of file dshot_erps.c.

Referenced by gcrEncode().

gcrNibbleInv

const uint8_t gcrNibbleInv[32]

static

Initial value:

= {
  0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 
  0xff, 0x9, 0xa, 0xb, 0xff, 0xd, 0xe, 0xf, 
  0xff, 0xff, 0x2, 0x3, 0xff, 0x5, 0x6, 0x7, 
  0xff, 0x0, 0x8, 0x1, 0xff, 0x4, 0xc, 0xff}

IBM GCR decoding lookup table.

Definition at line 15 of file dshot_erps.c.

Referenced by gcrDecode().