This page has moved into the new guide: Pathfinder 8-Way

Line Follower 8-ch: value & command reference

Every value and command the Line Follower 8-ch reports to each host: what it means, its range, and how to read it on SPIKE / EV3 / Arduino I2C / mBlock / MATRIX / micro:bit. Append ?host=spike (or ev3, arduino, mblock, matrix, microbit) to the URL to expand that host by default.

SPIKE EV3 Arduino I2C mBlock MATRIX micro:bit

Item	Detail
Factory I2C address	`0x16`
hw[0]	`8`（F0 high byte; ID high byte in SPIKE mode 8 / EV3 mode 5）
Model	`LINE8`
Protocol version	`2`
Hosts	SPIKE, EV3, Arduino I2C, mBlock, MATRIX, micro:bit

Values at a glance

Id	Value	Range	SPIKE	EV3	Arduino I2C	mBlock	MATRIX	micro:bit
`01`	line position	-8~+8	✓	✓	✓	✓	✓	✓
`02`	fine position	-100~+100	✓	✓	✓	✓	✓	✓
`03`	line width	0~8 路	✓	✓	✓	✓	✓	✓
`04`	line segments	0~4	✓	—	✓	✓	—	✓
`05`	line bitmap	0~255 bit	✓	✓	✓	✓	—	✓
`06`	last exit direction	-8~+8	—	—	✓	✓	—	✓
`07`	threshold	1~99	—	—	✓	✓	—	✓
`08`	calibrations done	0~255 次	—	—	✓	✓	—	✓
`10~17`	channel 1~8 reflect	0~100	✓	✓	✓	✓	✓	✓

✓ = available on that host; — = not sent.

Reading each value

`01` line position linePos

Item	Detail
Meaning	which channel the line is under: −8 (far left) to +8 (far right), 0 = centre; seen from behind the robot, negative = left
Range	`-8~+8`
I2C / mBlock id	`01`
Locked	🔒 LEGO mode layout will not change

How to read it

SPIKE

mode 0 (edu) byte 1 −8 🔒; mode 0 (toy) byte 0 −8 🔒; mode 1 byte 0 −8; mode 5 v[0] 🔒; mode 9 v[4] lo −8 🔒. Note: Pybricks reflection() 編碼：X = (線位置+8)×10 + 線寬（0~~168），共用核心 mbcReflFill8 送出：2026-11-01 以後的韌體 reflection() 剛好 = X（3.x、4.x 都是整數）；舊韌體（R=G=B=a×256+b）在 4.x 帶 0.3~~0.9 的小數，先 int()。主機 ÷10 取整−8 = 線位置、取餘數 = 線寬（INO:947-950）

from pybricks.iodevices import PUPDevice
from pybricks.parameters import Port

dev = PUPDevice(Port.A)   # sensor on port A

w = dev.read(9)[4]
linePos = (w & 0xFF) - 8   # line position（lo byte）

MBC library

from pybricks.parameters import Port
from MBC_line8_obj_Lib import MBC_LINE8

line = MBC_LINE8(Port.A)
linePos = line.pos8()

EV3

mode 0 · int8 · IR-PROX (locked mode: firmware and hosts will not change it)

from pybricks.iodevices import LUMPDevice
from pybricks.parameters import Port

sensor = LUMPDevice(Port.S1)   # sensor on port 1

linePos = sensor.read(0)[0]   # line position：-8~+8

' clev3r (BASIC)
Sensor.SetMode(1, 0)
linePos = Sensor.ReadRawValue(1, 0)

Arduino I2C

Returns MBC_NONE (−32768) when the module does not answer.

int16_t linePos = mbcRead(0x16, 0x01);   // line position：-8~+8

mBlock

Block returns line position（-8~+8）。Host sends [01] → reply [lo][hi][01 ^ lo ^ hi], value = int16 little-endian.

(Pathfinder port [1 v] line position :: sensing)

MATRIX

0x22 R (+8).

// A. stock 0x22 blocks：R = line position + 8
int linePos = MiniR4.I2C1.MXColor.getColor(R) - 8;

micro:bit

Returns 0 when the sensor does not answer; check with "device at … is ready" first.

(line position :: #00A4E4)

let linePos = mbc.linePosition()   // line position：-8~+8

Related examples：Arduino example 03、EV3 example 02、SPIKE example 02

`02` fine position linePosFine

Item	Detail
Meaning	sub-channel position: −100 to +100, 0 = centre, negative = left (same sign as line position)
Range	`-100~+100`
I2C / mBlock id	`02`
Locked	🔒 LEGO mode layout will not change

How to read it

SPIKE

mode 0 (edu) byte 2 −100 🔒; mode 3 byte 0 −100; mode 4 v[0] −100; mode 7 v[0] 🔒; mode 9 v[5] lo −100 🔒. Note: 4 個 int16：第 1、2、4 格 = (細位置+100)×100 + 線寬（0~20008；Pybricks hsv(surface=False).h 讀第 1 格，原封不動）；第 3 格 = (細位置+100)×100 + min(線寬,9)×10（Pybricks ambient() 讀這格：4.1.2 先 ÷10 去尾再 ÷10、3.6.1／4.0.0 ÷100，都得到細位置+100 . 線寬）。2026-10-30 起第 3 格改這個編碼

from pybricks.iodevices import PUPDevice
from pybricks.parameters import Port

dev = PUPDevice(Port.A)   # sensor on port A

w = dev.read(9)[5]
linePosFine = (w & 0xFF) - 100   # fine position（lo byte）

MBC library

from pybricks.parameters import Port
from MBC_line8_obj_Lib import MBC_LINE8

line = MBC_LINE8(Port.A)
linePosFine = line.pos100()

EV3

mode 2 · int8 · IR-REMOTE byte0 = highRes−100 存成 int8（F030 ev3Uart case 2），主機直接讀 (locked mode: firmware and hosts will not change it)

from pybricks.iodevices import LUMPDevice
from pybricks.parameters import Port

sensor = LUMPDevice(Port.S1)   # sensor on port 1

linePosFine = sensor.read(2)[0]   # fine position：-100~+100

' clev3r (BASIC)
Sensor.SetMode(1, 2)
linePosFine = Sensor.ReadRawValue(1, 0)

Arduino I2C

Returns MBC_NONE (−32768) when the module does not answer.

int16_t linePosFine = mbcRead(0x16, 0x02);   // fine position：-100~+100

mBlock

Block returns fine position（-100~+100）。Host sends [02] → reply [lo][hi][02 ^ lo ^ hi], value = int16 little-endian.

(Pathfinder port [1 v] fine line position :: sensing)

MATRIX

0x22 B (+100).

// A. stock 0x22 blocks：B = fine position + 100
int linePosFine = MiniR4.I2C1.MXColor.getColor(B) - 100;

micro:bit

Returns 0 when the sensor does not answer; check with "device at … is ready" first.

(fine line position :: #00A4E4)

let linePosFine = mbc.linePositionFine()   // fine position：-100~+100

Related examples：Arduino example 06、EV3 example 04

`03` line width lineWidth

Item	Detail
Meaning	number of channels on the line, 0~8; 0 = no line
Range	`0~8` 路
I2C / mBlock id	`03`
Locked	🔒 LEGO mode layout will not change

How to read it

SPIKE

mode 0 (edu) byte 0 🔒; mode 0 (toy) byte 1 🔒; mode 2 byte 0; mode 5 v[0] 🔒; mode 7 v[0] 🔒; mode 9 v[4] hi 🔒. Note: 跟線位置合在 reflection() 的個位數（見線位置）; 跟細位置合在一起（見細位置）：第 1、2、4 格是個位數（hsv(surface=False).h），第 3 格是十位數、最多 9（ambient() 的小數第 1 位）

from pybricks.iodevices import PUPDevice
from pybricks.parameters import Port

dev = PUPDevice(Port.A)   # sensor on port A

w = dev.read(9)[4]
lineWidth = ((w >> 8) & 0xFF)   # line width（hi byte）

MBC library

from pybricks.parameters import Port
from MBC_line8_obj_Lib import MBC_LINE8

line = MBC_LINE8(Port.A)
lineWidth = line.width()

EV3

mode 2 · int8 (locked mode: firmware and hosts will not change it)

from pybricks.iodevices import LUMPDevice
from pybricks.parameters import Port

sensor = LUMPDevice(Port.S1)   # sensor on port 1

lineWidth = sensor.read(2)[1]   # line width：0~8 路

' clev3r (BASIC)
Sensor.SetMode(1, 2)
lineWidth = Sensor.ReadRawValue(1, 1)

Arduino I2C

Returns MBC_NONE (−32768) when the module does not answer.

int16_t lineWidth = mbcRead(0x16, 0x03);   // line width：0~8 路

mBlock

Block returns line width（0~8 路）。Host sends [03] → reply [lo][hi][03 ^ lo ^ hi], value = int16 little-endian.

(Pathfinder port [1 v] line width :: sensing)

MATRIX

0x22 G.

// A. stock 0x22 blocks：G = line width
int lineWidth = MiniR4.I2C1.MXColor.getColor(G);

micro:bit

Returns 0 when the sensor does not answer; check with "device at … is ready" first.

(line width :: #00A4E4)

let lineWidth = mbc.lineWidth()   // line width：0~8 路

Related examples：Arduino example 03、EV3 example 03

`04` line segments groupCount

Item	Detail
Meaning	number of separate line segments: 0 = lost, 1 = one line, ≥2 = fork / crossing
Range	`0~4`
I2C / mBlock id	`04`

How to read it

SPIKE

mode 9 v[5] hi 🔒

from pybricks.iodevices import PUPDevice
from pybricks.parameters import Port

dev = PUPDevice(Port.A)   # sensor on port A

w = dev.read(9)[5]
groupCount = ((w >> 8) & 0xFF)   # line segments（hi byte）

MBC library

from pybricks.parameters import Port
from MBC_line8_obj_Lib import MBC_LINE8

line = MBC_LINE8(Port.A)
groupCount = line.junction()

EV3

Not sent in any EV3 mode (the locked EV3 modes stay as they are). Use Arduino I2C / mBlock if you need it.

Arduino I2C

Returns MBC_NONE (−32768) when the module does not answer.

int16_t groupCount = mbcRead(0x16, 0x04);   // line segments：0~4

mBlock

Block returns line segments（0~4）。Host sends [04] → reply [lo][hi][04 ^ lo ^ hi], value = int16 little-endian.

(Pathfinder port [1 v] line segments :: sensing)

MATRIX

Not available with the stock MATRIX 0x22 blocks.

micro:bit

Returns 0 when the sensor does not answer; check with "device at … is ready" first.

(line segments :: #00A4E4)

let groupCount = mbc.lineSegments()   // line segments：0~4

Related block "line is seen"

let lineSeen = mbc.lineSeen()

Related block "on line [lost]"

mbc.onLineEvent(MbcLineEvent.Lost, function () {
})

Related examples：Arduino example 05

`05` line bitmap bitmap

Item	Detail
Meaning	bit0 = channel 1 (left) … bit7 = channel 8; 1 = that channel sees the line
Range	`0~255` bit
I2C / mBlock id	`05`

How to read it

SPIKE

mode 4 v[1]; mode 9 v[6] lo 🔒

from pybricks.iodevices import PUPDevice
from pybricks.parameters import Port

dev = PUPDevice(Port.A)   # sensor on port A

w = dev.read(9)[6]
bitmap = (w & 0xFF)   # line bitmap（lo byte）

MBC library

from pybricks.parameters import Port
from MBC_line8_obj_Lib import MBC_LINE8

line = MBC_LINE8(Port.A)
bitmap = line.bin_raw()

EV3

mode 3 · int16 · #67 新：IR-REM-A 1×int16

from pybricks.iodevices import LUMPDevice
from pybricks.parameters import Port

sensor = LUMPDevice(Port.S1)   # sensor on port 1

bitmap = sensor.read(3)[0]   # line bitmap：0~255 bit

' clev3r (BASIC)
Sensor.SetMode(1, 3)
bitmap = Sensor.ReadRawValue(1, 0)

Arduino I2C

Returns MBC_NONE (−32768) when the module does not answer.

int16_t bitmap = mbcRead(0x16, 0x05);   // line bitmap：0~255 bit

mBlock

Block returns line bitmap（0~255 bit）。Host sends [05] → reply [lo][hi][05 ^ lo ^ hi], value = int16 little-endian.

(Pathfinder port [1 v] line bitmap :: sensing)

MATRIX

Not available with the stock MATRIX 0x22 blocks.

micro:bit

Returns 0 when the sensor does not answer; check with "device at … is ready" first.

(line bitmap :: #00A4E4)

let bitmap = mbc.lineBitmap()   // line bitmap：0~255 bit

Related block "channel 1 is on the line"

let lineChannelOnLine = mbc.lineChannelOnLine(1)

Related examples：Arduino example 05、EV3 example 06

`06` last exit direction lastDir

Item	Detail
Meaning	where the line was before it was lost: −8 to +8 (negative = left); keeps the last value
Range	`-8~+8`
I2C / mBlock id	`06`

How to read it

SPIKE

Not sent in any SPIKE mode (locked modes stay as they are). Use Arduino I2C / mBlock if you need it.

EV3

Not sent in any EV3 mode (the locked EV3 modes stay as they are). Use Arduino I2C / mBlock if you need it.

Arduino I2C

Returns MBC_NONE (−32768) when the module does not answer.

int16_t lastDir = mbcRead(0x16, 0x06);   // last exit direction：-8~+8

mBlock

Block returns last exit direction（-8~+8）。Host sends [06] → reply [lo][hi][06 ^ lo ^ hi], value = int16 little-endian.

(Pathfinder port [1 v] last exit direction :: sensing)

MATRIX

Not available with the stock MATRIX 0x22 blocks.

micro:bit

Returns 0 when the sensor does not answer; check with "device at … is ready" first.

(last exit direction :: #00A4E4)

let lastDir = mbc.lineLastDirection()   // last exit direction：-8~+8

Related examples：Arduino example 06

`07` threshold threshold

Item	Detail
Meaning	reflect threshold for 'on line', 1~99, default 50; set with E4
Range	`1~99`
I2C / mBlock id	`07`

How to read it

SPIKE

Not sent in any SPIKE mode (locked modes stay as they are). Use Arduino I2C / mBlock if you need it.

EV3

Not sent in any EV3 mode (the locked EV3 modes stay as they are). Use Arduino I2C / mBlock if you need it.

Arduino I2C

Returns MBC_NONE (−32768) when the module does not answer.

int16_t threshold = mbcRead(0x16, 0x07);   // threshold：1~99

mBlock

Block returns threshold（1~99）。Host sends [07] → reply [lo][hi][07 ^ lo ^ hi], value = int16 little-endian.

(Pathfinder port [1 v] threshold :: sensing)

MATRIX

Not available with the stock MATRIX 0x22 blocks.

micro:bit

Returns 0 when the sensor does not answer; check with "device at … is ready" first.

(line threshold :: #00A4E4)

let threshold = mbc.lineThreshold()   // threshold：1~99

Related examples：Arduino example 07

`08` calibrations done calibCount

Item	Detail
Meaning	number of calibrations completed since power-on (button calibrations included)
Range	`0~255` 次
I2C / mBlock id	`08`

How to read it

SPIKE

Not sent in any SPIKE mode (locked modes stay as they are). Use Arduino I2C / mBlock if you need it.

EV3

Not sent in any EV3 mode (the locked EV3 modes stay as they are). Use Arduino I2C / mBlock if you need it.

Arduino I2C

Returns MBC_NONE (−32768) when the module does not answer.

int16_t calibCount = mbcRead(0x16, 0x08);   // calibrations done：0~255 次

mBlock

Block returns calibrations done（0~255 次）。Host sends [08] → reply [lo][hi][08 ^ lo ^ hi], value = int16 little-endian.

(Pathfinder port [1 v] calibration count :: sensing)

MATRIX

Not available with the stock MATRIX 0x22 blocks.

micro:bit

Returns 0 when the sensor does not answer; check with "device at … is ready" first.

(line calibration count :: #00A4E4)

let calibCount = mbc.lineCalibrationCount()   // calibrations done：0~255 次

Related block "line follower is calibrating"

let lineCalibrating = mbc.lineCalibrating()

Related examples：Arduino example 04

`10~17` channel 1~8 reflect light

Item	Detail
Meaning	calibrated reflect of channel 1~~8, 0~~100 (channel 1 = left); ids 10~17
Range	`0~100`
I2C / mBlock id	`10~17`
Locked	🔒 LEGO mode layout will not change

How to read it

SPIKE

mode 0 (edu) byte 4 🔒; mode 9 v[0] 🔒. Note: 4-bit (v×10)>>6; 每 int16 兩路：lo = 奇數路、hi = 偶數路

from pybricks.iodevices import PUPDevice
from pybricks.parameters import Port

dev = PUPDevice(Port.A)   # sensor on port A

words = dev.read(9)[0:4]
light = []
for w in words:
    light.append(w & 0xFF)          # odd channel
    light.append((w >> 8) & 0xFF)   # even channel

MBC library

from pybricks.parameters import Port
from MBC_line8_obj_Lib import MBC_LINE8

line = MBC_LINE8(Port.A)
light = line.ir_calibration()   # list, channel 1 = [0]

EV3

mode 1 · int8 · IR-SEEK 8×int8 (locked mode: firmware and hosts will not change it)

from pybricks.iodevices import LUMPDevice
from pybricks.parameters import Port

sensor = LUMPDevice(Port.S1)   # sensor on port 1

light = sensor.read(1)[0:8]   # channel 1~8 reflect

' clev3r (BASIC)
Sensor.SetMode(1, 1)
light1 = Sensor.ReadRawValue(1, 0)   ' first; for the N-th use 0 + N - 1

Arduino I2C

Ids 0x10~0x17 are consecutive: one mbcReadMany call returns them from the same 10 ms snapshot.

int16_t light[8];
mbcReadMany(0x16, 0x10, 8, light);   // channel 1~8 reflect：0~100
for (uint8_t i = 0; i < 8; i++) { Serial.print(light[i]); Serial.print(' '); }
Serial.println();

mBlock

Block returns channel 1~~8 reflect（0~~100）。Host sends [10] → reply [lo][hi][10 ^ lo ^ hi], value = int16 little-endian; channel N uses id 0x10 + (N − 1).

(Pathfinder port [1 v] channel [1 v] reflect :: sensing)

MATRIX

0x22 C~K.

// A. stock 0x22 blocks：C~K = channel 1~8 reflect（C~K 兩路一組 convert9×10+convert9）
int raw = MiniR4.I2C1.MXColor.getColor(C);   // group 1

micro:bit

Returns 0 when the sensor does not answer; check with "device at … is ready" first.

(channel (1) reflect :: #00A4E4)

let light = mbc.lineChannel(1)   // channel 1~8 reflect：0~100 (N = 1~8)

Related examples：Arduino example 02、EV3 example 01

Write commands

Only Arduino I2C, mBlock and micro:bit can send commands; the SPIKE / EV3 ports are read-only.

`E0` black line mode blackLine

Item	Detail
Action	follow a black line (default); RAM only, back to the default after reset
Parameters	none
Busy flag	none (immediate)

How to send it

SPIKE

Pybricks + the MBC library only (not the official app or built-in ColorSensor blocks); needs sensor firmware from 2026-10 or later.

from pybricks.parameters import Port
from MBC_sensors import MBC_LINE8

line = MBC_LINE8(Port.A)
line.cmd(0xE0)   # black line mode
ok = line.wait_done()   # True = done; False = failed / rejected / timed out

EV3

The EV3 port carries no write commands: calibrate with the button on the sensor, change settings over Arduino I2C / mBlock.

Arduino I2C

mbcWrite(0x16, 0xE0);   // black line mode

mBlock

Host sends [E0] → reply [00][00][E0] (ack), then it runs.

Pathfinder port [1 v] black line mode :: sensing

MATRIX

Not available with the stock MATRIX 0x22 blocks.

micro:bit

line follower follow [black v] line :: #00A4E4

mbc.lineSetColor(MbcLineColor.Black)   // black line mode

`E1` white line mode whiteLine

Item	Detail
Action	follow a white line (F3 b1 = 1); RAM only, back to the default after reset
Parameters	none
Busy flag	none (immediate)

How to send it

SPIKE

Pybricks + the MBC library only (not the official app or built-in ColorSensor blocks); needs sensor firmware from 2026-10 or later.

from pybricks.parameters import Port
from MBC_sensors import MBC_LINE8

line = MBC_LINE8(Port.A)
line.cmd(0xE1)   # white line mode
ok = line.wait_done()   # True = done; False = failed / rejected / timed out

EV3

The EV3 port carries no write commands: calibrate with the button on the sensor, change settings over Arduino I2C / mBlock.

Arduino I2C

mbcWrite(0x16, 0xE1);   // white line mode

mBlock

Host sends [E1] → reply [00][00][E1] (ack), then it runs.

Pathfinder port [1 v] white line mode :: sensing

MATRIX

Not available with the stock MATRIX 0x22 blocks.

micro:bit

line follower follow [white v] line :: #00A4E4

mbc.lineSetColor(MbcLineColor.White)   // white line mode

`E2` calibrate black calibBlack

Item	Detail
Action	store the current reading as black (sensor over the black line), ~50 ms; saved to EEPROM
Parameters	none
Busy flag	F3 bit2（1 while running）

How to send it

SPIKE

Pybricks + the MBC library only (not the official app or built-in ColorSensor blocks); needs sensor firmware from 2026-10 or later.

from pybricks.parameters import Port
from MBC_sensors import MBC_LINE8

line = MBC_LINE8(Port.A)
line.cmd(0xE2)   # calibrate black
ok = line.wait_done()   # True = done; False = failed / rejected / timed out

EV3

The EV3 port carries no write commands: calibrate with the button on the sensor, change settings over Arduino I2C / mBlock.

Arduino I2C

mbcWrite(0x16, 0xE2);   // calibrate black
while (mbcRead(0x16, 0xF3) & (1 << 2)) delay(10);   // wait until F3 bit2 clears = done

mBlock

Host sends [E2] → reply [00][00][E2] (ack), then it runs; F3 bit2 = 1 while busy.

Pathfinder port [1 v] calibrate black :: sensing

MATRIX

Not available with the stock MATRIX 0x22 blocks.

micro:bit

line follower calibrate [current reading is black v] :: #00A4E4

mbc.lineCalibrate(MbcLineCalib.Black)   // calibrate black

`E3` calibrate white calibWhite

Item	Detail
Action	store the current reading as white (sensor over the white surface), ~50 ms; saved to EEPROM
Parameters	none
Busy flag	F3 bit2（1 while running）

How to send it

SPIKE

Pybricks + the MBC library only (not the official app or built-in ColorSensor blocks); needs sensor firmware from 2026-10 or later.

from pybricks.parameters import Port
from MBC_sensors import MBC_LINE8

line = MBC_LINE8(Port.A)
line.cmd(0xE3)   # calibrate white
ok = line.wait_done()   # True = done; False = failed / rejected / timed out

EV3

The EV3 port carries no write commands: calibrate with the button on the sensor, change settings over Arduino I2C / mBlock.

Arduino I2C

mbcWrite(0x16, 0xE3);   // calibrate white
while (mbcRead(0x16, 0xF3) & (1 << 2)) delay(10);   // wait until F3 bit2 clears = done

mBlock

Host sends [E3] → reply [00][00][E3] (ack), then it runs; F3 bit2 = 1 while busy.

Pathfinder port [1 v] calibrate white :: sensing

MATRIX

Not available with the stock MATRIX 0x22 blocks.

micro:bit

line follower calibrate [current reading is white v] :: #00A4E4

mbc.lineCalibrate(MbcLineCalib.White)   // calibrate white

`E4` set threshold setThreshold

Item	Detail
Action	threshold 1~99 (RAM only, back to 50 after reboot); on SPIKE an out-of-range value returns failed (state 2)
Parameters	threshold `1~99`（1 byte）
Busy flag	none (immediate)

How to send it

SPIKE

Pybricks + the MBC library only (not the official app or built-in ColorSensor blocks); needs sensor firmware from 2026-10 or later.

from pybricks.parameters import Port
from MBC_sensors import MBC_LINE8

line = MBC_LINE8(Port.A)
line.cmd(0xE4, 50)   # set threshold（threshold 1~99）
ok = line.wait_done()   # True = done; False = failed / rejected / timed out

EV3

The EV3 port carries no write commands: calibrate with the button on the sensor, change settings over Arduino I2C / mBlock.

Arduino I2C

mbcWrite(0x16, 0xE4, 50);   // set threshold（threshold 1~99）

mBlock

Host sends [E4][params…] → reply [00][00][E4] (ack), then it runs.

Pathfinder port [1 v] set threshold (50) :: sensing

MATRIX

Not available with the stock MATRIX 0x22 blocks.

micro:bit

line follower set threshold (50) :: #00A4E4

mbc.lineSetThreshold(50)   // set threshold

`E7` 5-second auto calibration calibAuto

Item	Detail
Action	sweep the sensor across black line and white surface for 5 s; min/max become the references; F3 b2 = 1 meanwhile
Parameters	none
Busy flag	F3 bit2（1 while running）

How to send it

SPIKE

Pybricks + the MBC library only (not the official app or built-in ColorSensor blocks); needs sensor firmware from 2026-10 or later.

from pybricks.parameters import Port
from MBC_sensors import MBC_LINE8

line = MBC_LINE8(Port.A)
line.cmd(0xE7)   # 5-second auto calibration
ok = line.wait_done(8000)   # True = done; False = failed / rejected / timed out

EV3

The EV3 port carries no write commands: calibrate with the button on the sensor, change settings over Arduino I2C / mBlock.

Arduino I2C

mbcWrite(0x16, 0xE7);   // 5-second auto calibration
while (mbcRead(0x16, 0xF3) & (1 << 2)) delay(10);   // wait until F3 bit2 clears = done

mBlock

Host sends [E7] → reply [00][00][E7] (ack), then it runs; F3 bit2 = 1 while busy.

Pathfinder port [1 v] 5-second auto calibration :: sensing

MATRIX

Not available with the stock MATRIX 0x22 blocks.

micro:bit

line follower calibrate [auto \(sweep for 5 s\) v] :: #00A4E4

mbc.lineCalibrate(MbcLineCalib.Auto)   // 5-second auto calibration

`E9` mirror left/right reverse

Item	Detail
Action	[0 normal / 1 mirrored]: for a sensor mounted backwards — channel order and line position are mirrored; calibration stays per physical channel; RAM only, 0 after reset (not in legacy mBlock); on SPIKE an out-of-range value returns failed (state 2)
Parameters	mirrored `0~1`（1 byte）
Busy flag	none (immediate)

How to send it

SPIKE

Pybricks + the MBC library only (not the official app or built-in ColorSensor blocks); needs sensor firmware from 2026-10 or later.

from pybricks.parameters import Port
from MBC_sensors import MBC_LINE8

line = MBC_LINE8(Port.A)
line.cmd(0xE9, 1)   # mirror left/right（mirrored 0~1）
ok = line.wait_done()   # True = done; False = failed / rejected / timed out

EV3

The EV3 port carries no write commands: calibrate with the button on the sensor, change settings over Arduino I2C / mBlock.

Arduino I2C

mbcWrite(0x16, 0xE9, 1);   // mirror left/right（mirrored 0~1）

MATRIX

Not available with the stock MATRIX 0x22 blocks.

micro:bit

No dedicated block; in JavaScript use mbc.writeCmd(0x16, 0xE9, [params]).

Status flags F3

One status per bit of F3; read directly over I2C, mBlock, micro:bit.

bit	Name	Meaning
b0	ready (`ready`)	always 1
b1	white line mode (`whiteMode`)	1 = following a white line
b2	calibrating (`calibrating`)	E2/E3/E7 in progress; new calibration commands are ignored
b3	line lost (`lost`)	segment count = 0
b4	fork (`fork`)	segment count ≥ 2
b5	mirrored (`reversed`)	E9 = 1 (sensor mounted backwards, left/right mirrored)

SPIKE

SPIKE has no F3 flags; mode 8 returns ID / version. The official app cannot read mode 8.

from pybricks.iodevices import PUPDevice
from pybricks.parameters import Port

dev = PUPDevice(Port.A)   # sensor on port A

id_word, proto, fw, seq = dev.read(8)   # mode 8: [ID | hw0<<8, protocol 2, major×100+minor, counter]
addr = id_word & 0xFF   # 0x16
hw0 = id_word >> 8      # 8

EV3

EV3 has no F3 flags; mode 5 returns the device ID and firmware version (ID format B).

from pybricks.iodevices import LUMPDevice
from pybricks.parameters import Port

sensor = LUMPDevice(Port.S1)   # sensor on port 1

id_word, fw = sensor.read(5)   # mode 5: [ID | hw0<<8, major×100+minor]
addr = id_word & 0xFF             # 0x16
hw0 = id_word >> 8                # 8

Arduino I2C

int16_t st = mbcRead(0x16, 0xF3);
bool ready = st & (1 << 0);   // ready
bool whiteMode = st & (1 << 1);   // white line mode
bool calibrating = st & (1 << 2);   // calibrating
bool lost = st & (1 << 3);   // line lost
bool fork = st & (1 << 4);   // fork
bool reversed = st & (1 << 5);   // mirrored

mBlock

The extension splits status flags F3 into boolean blocks (ready, calibrating, …).

MATRIX

The status flags are not available with the stock MATRIX 0x22 blocks.

micro:bit

let ready = mbc.deviceReady(0x16)   // F3 bit0; false when nothing answers
let st = mbc.status(0x16)   // F3

Shared registers and commands

Identical on every product, documented once in the universal I2C protocol:

Id	Name	Meaning
`F0`	device ID	low byte = factory I2C address (unchanged after re-addressing), high byte = hw[0] (channels / sensors / variant)
`F1`	protocol version	2 for this release (same number reported in SPIKE mode 8 v[1])
`F2`	firmware version	major×100 + minor (e.g. 102 = 1.2)
`F3`	status flags	b0 = ready; other bits per product (see flags)
`F4`	update counter	+1 every 10 ms snapshot, wraps 0~255 (2.56 s per cycle, not usable for reboot detection; frozen = module busy)
`F5`	uptime seconds	seconds since boot, saturates at 32767 (~9 h); a drop means the module rebooted
`F8`	change I2C address	[F8][new 0x08~~0x77][~~new], saved to EEPROM, takes effect after reboot; [F8][0x00][0xFF] = back to factory address
`EF`	reboot	[EF][0xA5]; mBlock sends ACK first, then reboots

Sources and assumptions

Generated by _build/gen-reference.mjs from _build/protocol/line8.json (single source of truth, transcribed from the 2026-10-21 protocol decisions).

B-11：細位置 02 與線位置 01 同號（負 = 左）；v1 韌體註解寫反，程式碼同號。
B-12：E7 五秒動態校準補回（v1 的 0x20=0x01），定案表沒列。
SPIKE 教育版模式 0 的 byte 8~15 補 0（#65 已改，使用者保留）。
EV3 模式 4 與模式 2 相同內容；模式 3 改壓線位元圖（#67）。
mBlock 舊版：MBC_MBLOCK_LEGACY=1 時逐 byte 同 2026-10-21 統一後韌體，0x0B 回 1。