MPU6500 is an inertial measurement unit that integrates a three-axis gyroscope, a three-axis accelerometer and a digital motion processor. It can achieve high-precision, low-power motion tracking and calculation, and has high dynamics and stability. , gesture recognition, navigation and other fields have a wide range of applications. MPU6500 supports I2C and SPI two kinds of communication interfaces, has the characteristics of small size, low cost, high performance, etc., it is an ideal inertial measurement unit.
MPU6500 has two basic working modes: sampling mode and FIFO mode.
FIFO mode means that the MPU6500 stores continuous sensor data in an internal cache in time order, and the host processor can read data from the cache on demand without having to process the raw data in real time. The FIFO mode takes advantage of the temporal continuity of sensor data, and can easily implement functions such as data caching, data compression, and data transmission.
The following is a detailed analysis of the FIFO mode of the MPU6500:
1. Open FIFO mode
MPU6500 supports three FIFO modes: FIFO off, FIFO overflow interrupt and FIFO full speed mode. FIFO mode can be enabled by register configuration.
2. The size of the FIFO buffer
The FIFO cache of MPU6500 can store 512 16-bit data. Among them, the three-axis accelerometer, three-axis gyroscope and three-axis magnetometer data can be stored at the same time. Because these data are not collected at the same time, the available space of the FIFO cache is not exactly the same in fact.
3. Use of FIFO mode
In FIFO mode, the MPU6500 will automatically store new sensor data in the cache. When the cache is full, the MPU6500 will automatically discard the oldest sensor data and store the latest data. The host processor can obtain raw sensor data by reading the data in the FIFO buffer.
4. Interrupt in FIFO mode
MPU6500 supports FIFO overflow interrupt, which can trigger an interrupt when the buffer is full. The host processor can detect the FIFO overflow interrupt by accessing the interrupt flag bit, and process the data in the buffer in time.
5. Application of FIFO mode
The FIFO mode of MPU6500 is widely used in IoT, smart home, automatic driving and other fields. For example, in IoT applications, the MPU6500 can be used to monitor the motion status of vehicles, robots, drones, etc. in real time to provide more precise control and management. In smart home applications, MPU6500 can be used to realize gesture control of smart home devices to improve user interaction experience. In automatic driving applications, the MPU6500 can be used to monitor the vehicle's motion status and environmental information in real time to achieve a safer and more efficient automatic driving system.
The following are the configuration steps of MPU6500 FIFO mode:
1. Select normal operating mode or low power mode. To enable FIFO mode, normal operating mode must be used.
2. Configure the sampling frequency and low-pass filter settings. Select the appropriate frequency and filter settings as desired.
3. Configure the FIFO mode. Select the FIFO mode and specify the desired FIFO amount.
4. Configure FIFO interrupt. If it is necessary to receive a notification when the FIFO is full or reaches a certain threshold, a FIFO interrupt must be configured.
5. Enable FIFO mode. When FIFO mode is enabled, the sensor stores data in a FIFO buffer.
6. Read FIFO data. Read FIFO data through SPI or I2C interface.
The following aspects should be paid attention to during the use of MPU6500 chip FIFO:
1. Before reading FIFO data, make sure that the MPU6500 chip has entered the FIFO buffer mode, and the data type and sampling frequency have been configured.
2. Before reading FIFO data, clear the FIFO overflow flag.
3. When processing FIFO data, it should be considered that FIFO data may be lost due to overflow, so an appropriate algorithm should be used to deal with data loss.
4. In order to avoid the FIFO data being read multiple times, it is recommended to clear the data in the FIFO buffer immediately after reading the FIFO data.
In short, the FIFO mode of the MPU6500 chip can greatly simplify the process of data reading and processing, but it should be noted that the FIFO data may be lost due to overflow.