GY521  0.3.7
GY521 Documentation

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GY521

Arduino library for I2C GY521 accelerometer-gyroscope sensor a.k.a. MCU-6050.

Description

Experimental library for GY521 a.k.a. MCU-6050.

Library is work in progress, in fact it is extracted and extended from an old project. It needs to be tested a lot more.

Examples

  • calibration example to determine the offsets needed
  • example to read values.
  • test sketch to test get / set values.
  • example to get pitch roll yaw.
  • performance sketch.

Breakout board

From left to right

pin pinName description
0 VCC +5V
1 GND ground
2 SCL I2C clock
3 SDA I2C data

| 4 | XDA | auxiliary data | see datasheet | 5 | XCL | auxiliary clock | see datasheet | 6 | AD0 | address | | 7 | INT | interrupt |

Address

AD0 connected to GND => 0x68 AD0 connected to VCC => 0x69

Calibration (short version for now)

  1. load and run calibration example

    it shows a header containing 6 numbers and 10 lines of 8 numbers

  1. wait until the middle 6 of the longer lines stabilize (should all be 0)
  1. copy the 6 numbers above the axe aye aze as these are the numbers needed.

Interface

Constructor

  • GY521(uint8_t address = 0x69, , TwoWire *wire = &Wire) Constructor with default address. 0x68 is also a valid address. The wire argument is optional to select Wire1 Wire2 etc. on some boards.
  • bool begin(uint8_t sda, uint8_t scl) begin for ESP32 et al. Returns true if address can be found on I2C bus.
  • bool begin() Returns true if address can be found on I2C bus.
  • bool isConnected() returns true if device can be found on I2C bus.
  • void reset() set all internal values to 0 and throttle time to 10 ms.
  • bool wakeUp() idem.

Throttle

  • void setThrottle(bool throttle = true) throttle to force "delay" between reads.
  • bool getThrottle() returns true if throttle mode is set.
  • void setThrottleTime(uint16_t ti ) throttle time in milliseconds, max = 65535 = 1++ minute
  • uint16_t getThrottleTime() returns throttle time set.

READ

Set before read

  • bool setAccelSensitivity(uint8_t as) as = 0, 1, 2, 3 ==> 2g 4g 8g 16g
  • uint8_t getAccelSensitivity() returns 0, 1, 2, 3
  • bool setGyroSensitivity(uint8_t gs) gs = 0,1,2,3 ==> 250, 500, 1000, 2000 degrees/second
  • uint8_t getGyroSensitivity() returns 0, 1, 2, 3

Actual read

  • int16_t read() returns status = GY521_OK on success.
  • int16_t readAccel() read accelerometer only to speed up interaction. This call does update the throttle timer. returns status = GY521_OK on success.
  • int16_t readGyro() read gyroscope only to speed up interaction. This call does update the throttle timer. returns status = GY521_OK on success. Note: for pitch roll yaw you need to call read().
  • int16_t readTemperature() read temperature only, does not update the throttle timer. returns status = GY521_OK on success.
  • uint32_t lastTime() last time sensor is actually read. In milliseconds. Not updated by readTemperature().

Call after read

Note that multiple calls will return the same value. One must explicitly call read() to get new values.

  • float getAccelX() idem
  • float getAccelY() idem
  • float getAccelZ() idem
  • float getAngleX() idem
  • float getAngleY() idem
  • float getAngleZ() idem
  • float getTemperature() idem
  • float getGyroX() idem
  • float getGyroY() idem
  • float getGyroZ() idem
  • float getPitch() idem
  • float getRoll() idem
  • float getYaw() idem

Register access

Read the register PDF for the specific value and meaning of registers.

  • uint8_t setRegister(uint8_t reg, uint8_t value)
  • uint8_t getRegister(uint8_t reg)

documents

  • check details - MPU-6000-Register-Map1.pdf

Operation

See examples, use with care

Future

Should

  • test test and test ...(ESP too)
  • improve documentation
  • look for maths optimizations (atan, hypot, performance)

Could

  • calibrate function in the lib ? (think not as lib might grow?)
  • calibrate sketch could print code snippet to include...