/* * IMU Gyro x Arduino Example 1: Say hello to the gyro * ------------------------------------------------------------ * What does this example do? * Checks that the gyro is connected. If it is, it prints the gyro's "ID card" * (device ID, protocol version, firmware version) and the 8 bits of status * flags F3 (still? calibrating? mounted crooked?). * Run this example first every time you connect a new gyro. * * You need: IMU Gyro (Universal I2C edition), Arduino UNO / Nano / UNO R4 or ESP32. * * Wiring: * Gyro VCC -> 5V Gyro GND -> GND * Gyro SDA -> A4 Gyro SCL -> A5 (UNO / Nano) * UNO R4: SDA / SCL pins; ESP32: GPIO 21 (SDA) / GPIO 22 (SCL) * * How to see the result: * After uploading, open the Serial Monitor and choose 115200 baud. * * Tip: * Keep the gyro still for about 0.5 s when it powers on. It learns "which side is up" * by itself and sets the heading to zero. */ #include // Arduino's built-in I2C tool, used to talk to the gyro const uint8_t ADDR = 0x6A; // The IMU Gyro's "house number" (I2C address) const int16_t MBC_NONE = -32768; // Code for "no such value / could not read" // Helper declaration (the code is at the bottom of the file); mbcWrite's parameters can be left out bool mbcWrite(uint8_t addr, uint8_t id, const uint8_t *p = NULL, uint8_t n = 0); void setup() { Serial.begin(115200); // Open the channel to the computer at 115200 baud mbcBegin(); // Get I2C ready (helper at the bottom of the file) delay(500); // Give the gyro 0.5 s to boot Serial.println(F("=== IMU Gyro: Say hello to the gyro ===")); // Wait until the gyro says "I am ready" (bit0 of status flags F3), up to 3 seconds if (!mbcWaitReady(ADDR, 3000)) { Serial.println(F("Gyro not found! Please check:")); Serial.println(F(" 1. SDA -> A4, SCL -> A5 (ESP32: 21 / 22). Are they swapped?")); Serial.println(F(" 2. VCC -> 5V, GND -> GND. Plugged in firmly?")); Serial.println(F(" 3. Is your gyro the Universal I2C edition? (SPIKE and EV3 editions cannot connect to Arduino)")); while (true) {} // Stop here if not found } // ---- F0 device ID: low byte = factory address (0x6A), high byte = hw[0] (IMU = 1) ---- int16_t id = mbcRead(ADDR, 0xF0); Serial.print(F("Found it! Factory address 0x")); Serial.print((uint8_t)(id & 0xFF), HEX); Serial.print(F(", type code ")); Serial.println((uint8_t)((id >> 8) & 0xFF)); // IMU = 1 // ---- F1 protocol version (these examples are written for version 2) ---- Serial.print(F("Protocol version: ")); Serial.println(mbcRead(ADDR, 0xF1)); // ---- F2 firmware version: major x 100 + minor (for example 102 = 1.2) ---- int16_t fw = mbcRead(ADDR, 0xF2); Serial.print(F("Firmware version: ")); Serial.print(fw / 100); Serial.print('.'); Serial.println(fw % 100); // ---- F3 status flags: 8 bits, each bit means one thing ---- int16_t st = mbcRead(ADDR, 0xF3); Serial.println(F("Current status:")); printFlags(st); // ---- F5 seconds since power-on ---- Serial.print(F("Seconds since power-on: ")); Serial.println(mbcRead(ADDR, 0xF5)); Serial.println(F("Wiring is correct. You can try the other examples now!")); } void loop() { // This example only checks once at power-on, so loop does nothing } // Print the 8 bits of F3, one line each void printFlags(int16_t st) { Serial.print(F(" bit0 ready ")); Serial.println((st & 0x01) ? F("yes") : F("no")); Serial.print(F(" bit1 still ")); Serial.println((st & 0x02) ? F("yes") : F("no (moving)")); Serial.print(F(" bit2 mounting axis captured ")); Serial.println((st & 0x04) ? F("yes (knows which side is up)") : F("no (keep it still and wait)")); Serial.print(F(" bit3 mounted crooked ")); Serial.println((st & 0x08) ? F("yes (please mount it flatter)") : F("no")); Serial.print(F(" bit4 accel calibrating ")); Serial.println((st & 0x10) ? F("yes") : F("no")); Serial.print(F(" bit5 mag calibrating ")); Serial.println((st & 0x20) ? F("yes") : F("no")); Serial.print(F(" bit6 mag fusion initialized ")); Serial.println((st & 0x40) ? F("yes (fused heading available)") : F("no")); Serial.print(F(" bit7 mag auto-cal converged ")); Serial.println((st & 0x80) ? F("yes") : F("no")); } // ============================================================ // Below are the "Communication helpers" (MBC I2C protocol v2): they talk to the sensor. // They are the same in every MBC example. No need to change or understand them. // How to read: write [number] -> wait 2 ms -> read 2 x k bytes = k int16 values (little-endian) starting at that number // If the number does not exist (empty slot), the sensor returns -32768 (MBC_NONE) // ============================================================ // Start I2C (call once in setup) // UNO/Nano: SDA=A4, SCL=A5; UNO R4: SDA/SCL pins; ESP32: default GPIO21(SDA)/22(SCL) void mbcBegin() { Wire.begin(); #if defined(WIRE_HAS_TIMEOUT) Wire.setWireTimeout(25000, true); // If a wire is loose, the Arduino will not freeze #endif } // From the sensor at address addr, read k values (1~16) in a row starting at number id, into out. Returns true if all were read bool mbcReadMany(uint8_t addr, uint8_t id, uint8_t k, int16_t *out) { if (k < 1) k = 1; if (k > 16) k = 16; // At most 16 values at a time (32 bytes, the Wire buffer limit) Wire.beginTransmission(addr); Wire.write(id); // Tell the sensor: I want to read starting at number id if (Wire.endTransmission() != 0) return false; delay(2); // Wait 2 ms before reading (ESP32-based products need this) uint8_t n = (uint8_t)(2 * k); if (Wire.requestFrom(addr, n) != n) return false; for (uint8_t i = 0; i < k; i++) { uint16_t lo = Wire.read(); // The low byte comes first uint16_t hi = Wire.read(); // Then the high byte (little-endian) out[i] = (int16_t)(uint16_t)(lo | (hi << 8)); } return true; } // Read one value. Returns MBC_NONE if it cannot be read (not connected) int16_t mbcRead(uint8_t addr, uint8_t id) { int16_t v; return mbcReadMany(addr, id, 1, &v) ? v : MBC_NONE; } // Send a command: write [id][parameters...]. p points to the parameters, n = how many bytes (leave out if none). Returns true on success bool mbcWrite(uint8_t addr, uint8_t id, const uint8_t *p, uint8_t n) { Wire.beginTransmission(addr); Wire.write(id); for (uint8_t i = 0; i < n; i++) Wire.write(p[i]); return Wire.endTransmission() == 0; } // Wait until the sensor is ready (bit0 of status flags F3 = 1), up to ms milliseconds. Returns true when ready bool mbcWaitReady(uint8_t addr, uint16_t ms) { unsigned long start = millis(); while (millis() - start < ms) { int16_t f = mbcRead(addr, 0xF3); if (f != MBC_NONE && (f & 1)) return true; delay(50); } return false; }