Line Follower 8-ch × Arduino I2C (universal I2C edition)

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The universal I2C edition of the Line Follower 8-ch speaks MBC I2C protocol v2: write one id, read 2 bytes = one int16 little-endian value; consecutive ids can be read in one go. This page has the value table, commands and wiring for this product; the shared rules (F0~F5 version & status, F8 re-address, EF reboot) are on the universal I2C protocol page.

SPIKEEV3Arduino I2CmBlockMATRIXmicro:bit

Tip

New to coding? Start with the Arduino examples; every sketch is copy-and-upload. The six-host reading of every value is in the reference.

Basics

Wiring

Works directly with 5 V hosts, no level shifter; two products with the same address cannot share a bus (re-address one with F8 first).

Value table

Each id returns one int16; click an id for the six-host reading and figure.

Write commands

Status flags F3

Shared registers

Single-file helper functions

No library to install. Paste it in two parts: part ① (2 lines) at the top of the sketch, part ② at the bottom. #include <Wire.h> and MBC_NONE must appear before setup() uses them; pasting everything at the bottom will not compile.

① At the top of your sketch (before setup())

#include <Wire.h>

const int16_t MBC_NONE = -32768;   // no answer / undefined id

② At the bottom of your sketch (after loop())

// read k consecutive values (k ≤ 16) starting at id, int16 little-endian
bool mbcReadMany(uint8_t addr, uint8_t id, uint8_t k, int16_t *out) {
  Wire.beginTransmission(addr);
  Wire.write(id);
  if (Wire.endTransmission() != 0) return false;
  delay(2);                                        // always wait 2 ms (ESP32 products cannot clock-stretch)
  if (Wire.requestFrom(addr, (uint8_t)(k * 2)) != (uint8_t)(k * 2)) return false;
  for (uint8_t i = 0; i < k; i++) {
    uint8_t lo = Wire.read(), hi = Wire.read();
    out[i] = (int16_t)(lo | (hi << 8));
  }
  return true;
}

// read one value; MBC_NONE when nothing answers
int16_t mbcRead(uint8_t addr, uint8_t id) {
  int16_t v;
  return mbcReadMany(addr, id, 1, &v) ? v : MBC_NONE;
}

// write a command (0~3 parameters)
// with 2 parameters whose first is 0, write (uint8_t)0, e.g. mbcWrite(ADDR, 0xF8, (uint8_t)0x00, 0xFF); otherwise it clashes with the array form below and will not compile
void mbcWrite(uint8_t addr, uint8_t id, const uint8_t *args, uint8_t n) {
  Wire.beginTransmission(addr);
  Wire.write(id);
  for (uint8_t i = 0; i < n; i++) Wire.write(args[i]);
  Wire.endTransmission();
}
void mbcWrite(uint8_t addr, uint8_t id) { mbcWrite(addr, id, nullptr, 0); }
void mbcWrite(uint8_t addr, uint8_t id, uint8_t a) { mbcWrite(addr, id, &a, 1); }
void mbcWrite(uint8_t addr, uint8_t id, uint8_t a, uint8_t b) { uint8_t p[2] = {a, b}; mbcWrite(addr, id, p, 2); }
void mbcWrite(uint8_t addr, uint8_t id, uint8_t a, uint8_t b, uint8_t c) { uint8_t p[3] = {a, b, c}; mbcWrite(addr, id, p, 3); }

// wait until ready (F3 bit0 = 1), at most ms milliseconds
bool mbcWaitReady(uint8_t addr, unsigned long ms) {
  unsigned long t0 = millis();
  while (millis() - t0 < ms) {
    int16_t st = mbcRead(addr, 0xF3);
    if (st != MBC_NONE && (st & 1)) return true;
    delay(20);
  }
  return false;
}

Example: print the whole value table

// helper part ①
#include <Wire.h>

const int16_t MBC_NONE = -32768;   // no answer / undefined id

const uint8_t ADDR = 0x16;

void setup() {
  Serial.begin(115200);
  Wire.begin();
#if defined(WIRE_HAS_TIMEOUT)
  Wire.setWireTimeout(25000, true);   // AVR: never hang when the module is silent
#endif
  if (!mbcWaitReady(ADDR, 2000)) Serial.println("module not found: check wiring and address");
  Serial.print("ID 0x"); Serial.println(mbcRead(ADDR, 0xF0), HEX);   // low byte address, high byte hw[0]
  Serial.print("FW ");    Serial.println(mbcRead(ADDR, 0xF2));
}

void loop() {
  Serial.print("linePos: "); Serial.println(mbcRead(ADDR, 0x01));   // line position
  Serial.print("linePosFine: "); Serial.println(mbcRead(ADDR, 0x02));   // fine position
  Serial.print("lineWidth: "); Serial.println(mbcRead(ADDR, 0x03));   // line width
  Serial.print("groupCount: "); Serial.println(mbcRead(ADDR, 0x04));   // line segments
  Serial.print("bitmap: "); Serial.println(mbcRead(ADDR, 0x05));   // line bitmap
  Serial.print("lastDir: "); Serial.println(mbcRead(ADDR, 0x06));   // last exit direction
  Serial.print("threshold: "); Serial.println(mbcRead(ADDR, 0x07));   // threshold
  Serial.print("calibCount: "); Serial.println(mbcRead(ADDR, 0x08));   // calibrations done
  { int16_t a[8]; mbcReadMany(ADDR, 0x10, 8, a); Serial.print("light: "); for (uint8_t i = 0; i < 8; i++) { Serial.print(a[i]); Serial.print(' '); } Serial.println(); }
  Serial.println();
  delay(200);
}

// paste part ② of the helper functions below

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。
• Pin table uses each board's common defaults (ESP32: change with Wire.begin(sda, scl)).