LPS25HB 气压计参考手册中关于FIFO功能的解读

FIFO 普通模式

1、FIFO 模式的选定 (F_MODE[2:0] in FIFO_CTRL (2Eh) set to ‘001’)
2、FIFO 数据的读取 PRESS_OUT_H (2Ah), PRESS_OUT_L (29h), and PRESS_OUT_XL (28h)
3、水阈中断：(STOP_ON_FTH bit set to ‘1’ in CTRL_REG2 (21h))
in order to be raised when the FIFO is filled to the level specified by the WTM_POINT[4:0]
bits of FIFO_CTRL (2Eh). 如果FIFO满了，停止更新数据。

FIFO Stream 模式

1、Stream 模式的选定 (F_MODE[2:0] in FIFO_CTRL (2Eh) set to ‘010’),
2、FIFO 数据的读取 PRESS_OUT_H (2Ah), PRESS_OUT_L (29h), and PRESS_OUT_XL (28h)
注意： FIFO的Stream模式，没有水阈状态的更新。当FIFO满的时候，老的数据会被新的数据更新。当然可以使能中断的功能。

Stream-to-FIFO 模式

1、Stream-to-FIFO的选定((F_MODE[2:0] in FIFO_CTRL (2Eh) set to ‘011’),
2、FIFO 数据的读取 PRESS_OUT_H (2Ah), PRESS_OUT_L (29h), and PRESS_OUT_XL (28h)
3、水阈中断：(STOP_ON_FTH bit set to ‘1’ in CTRL_REG2 (21h))
in order to be raised when the FIFO is filled to the level specified by the WTM_POINT[4:0]
bits of FIFO_CTRL (2Eh). 如果FIFO满了，老数据会被新数据更新。
4、如果触发事件产生了，FIFO的状态可以转为FIFO的普通模式。触发方式配置寄存器INTERRUPT_CFG (24h).

Bypass-to-Stream 模式

1、Bypass-to-Stream 模式的选定(F_MODE[2:0] in FIFO_CTRL (2Eh) set to ‘100’),
2、触发方式设置INTERRUPT_CFG (24h). 利用触发方式将ByPass 模式转为Stream 模式，中断源INT_SOURCE (25h) 的IA位来判断

FIFO Mean 模式

1、FIFO Mean模式的选定(F_MODE[2:0] in FIFO_CTRL (2Eh) set to ‘110’),
2、FIFO Mean模式的特点：In this mode the FIFO is used to implement a moving average of the pressure data with a 2, 4, 8, 16 or 32 sample set by changing the FIFO Mean mode sample size defined by the WTM_POINT[4:0] bits of FIFO_CTRL (2Eh) (refer to Table 9).
3、该模式下的数据读取：
There are two possible ways of providing the output pressure data averaged by FIFO:

If the FIFO_MEAN_DEC bit in CTRL_REG2 (21h) is set to ‘0’, the output is at the same
ODR of the data coming from the sensor;
If the FIFO_MEAN_DEC bit in CTRL_REG2 (21h) is set to ‘1’, the output is decimated
(@1 Hz when ODR = 4 or 2; @1.04 Hz when ODR=3).
注意：该模式下，不允许直接读取FIFO的内容。

Bypass-to-FIFO 模式

1、Bypass-to-FIFO 模式的选定(F_MODE[2:0] in FIFO_CTRL (2Eh) set to ‘111’),
2、触发方式设置INTERRUPT_CFG (24h). 利用触发方式将ByPass 模式转为Stream 模式，中断源INT_SOURCE (25h) 的IA位来判断

寄存器表：

总上表中可以将寄存器总结如下：

**控制寄存器：**Control registers、Interrupt registers、FIFO configure registers、Resolution register
状态寄存器：Status register
参数寄存器：Who am I register、Reference pressure 、Pressure threshold registers、Pressure offset registers
数据输出寄存器：Pressure output registers、Temperature output registers