Vision Sensor (School Edition) × Arduino I2C (universal I2C edition)

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The universal I2C edition of the Vision Sensor (School Edition) 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.

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 = 0x4C;

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("hue: "); Serial.println(mbcRead(ADDR, 0x01));   // hue
  Serial.print("saturation: "); Serial.println(mbcRead(ADDR, 0x02));   // saturation
  Serial.print("value: "); Serial.println(mbcRead(ADDR, 0x03));   // brightness
  Serial.print("motion: "); Serial.println(mbcRead(ADDR, 0x04));   // motion
  Serial.print("blobX: "); Serial.println(mbcRead(ADDR, 0x05));   // blob X
  Serial.print("blobY: "); Serial.println(mbcRead(ADDR, 0x06));   // blob Y
  Serial.print("blobW: "); Serial.println(mbcRead(ADDR, 0x07));   // blob width
  Serial.print("blobH: "); Serial.println(mbcRead(ADDR, 0x08));   // blob height
  Serial.print("blobArea: "); Serial.println(mbcRead(ADDR, 0x09));   // blob area
  Serial.print("found: "); Serial.println(mbcRead(ADDR, 0x0A));   // blob found
  Serial.println();
  delay(200);
}

// paste part ② of the helper functions below

Sources and assumptions

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

• hw0 = 1（共識 #6：神攝手 1 = 學校版）；model 字串 CAMSCH 照任務指定（韌體原本沒有型號欄位）。
• D4：I2C 0x4C 用 SDA = IO3、SCL = IO1（沿 PS4 Wire.setPins 慣例），與 EV3／SPIKE 串口模式二選一編譯；ESP32 從機不能時脈延展，onReceive 預載 32 B；頁面標「硬體已確認，上機待測」。mBlock 用同一組腳 Serial.begin(38400, SERIAL_8N1, 3, 1)。
• EV3 六個模式全部鎖住照盤點（模式 3／5 的 −1 已在 #65 修成符號延伸）；EV3 定案最後的 golden 備註把 cam_school 列進「模式 5 改 ID」是筆誤（定案表本身寫「—」；模式 5 仍是 [色相, 飽和]），所以 ev3IdMode = null。
• SPIKE 模式 9 鎖住，只有 byte 89（v[4]）從 0 改成面積 W×H；模式 6 改 [X, Y, 面積]；模式 8 = [0x4C | 1<<8, 2, 韌體版, 更新序號]；模式 14 維持 0。
• SPIKE 模式 0 的「面積」是 map(像素面積 05000 → 0100)，跟值表 09 的 W×H 不同，鎖住不改（照盤點）。
• mVision：N = 10（idx 0~9），色相 −1 送 255；每 20 ms 一包（B-6）；不做 0x22（hosts.matrix = false）。
• 0A 有找到色塊 = W > 0（盤點：W 0 = 沒找到）；F3 b1 同這個值。
• 值 05~08 的「沒找到 = 0」照盤點 §0；色塊 Y 下 = 0、上 = 75 照盤點（map(bestY,120,0,0,75)）。
• 沒有寫入命令（韌體無法從程式改目標顏色／補光燈）。
• Pin table uses each board's common defaults (ESP32: change with Wire.begin(sda, scl)).