文章目錄

• LPS25HB 氣壓計(jì) 參考手冊(cè)中關(guān)于FIFO功能的解讀
• • FIFO 普通模式
  • FIFO Stream 模式
  • Stream-to-FIFO 模式
  • Bypass-to-Stream 模式
  • FIFO Mean 模式
  • Bypass-to-FIFO 模式
  • 寄存器表：

LPS25HB 氣壓計(jì) 參考手冊(cè)中關(guān)于FIFO功能的解讀

FIFO 普通模式

1、FIFO 模式的選定 (F_MODE[2:0] in FIFO_CTRL (2Eh) set to ‘001’)
2、FIFO 數(shù)據(jù)的讀取 PRESS_OUT_H (2Ah), PRESS_OUT_L (29h), and PRESS_OUT_XL (28h)
3、水閾中斷：(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滿了，停止更新數(shù)據(jù)。

FIFO Stream 模式

1、Stream 模式的選定 (F_MODE[2:0] in FIFO_CTRL (2Eh) set to ‘010’),
2、FIFO 數(shù)據(jù)的讀取 PRESS_OUT_H (2Ah), PRESS_OUT_L (29h), and PRESS_OUT_XL (28h)
注意： FIFO的Stream模式，沒有水閾狀態(tài)的更新。當(dāng)FIFO滿的時(shí)候，老的數(shù)據(jù)會(huì)被新的數(shù)據(jù)更新。當(dāng)然可以使能中斷的功能。

Stream-to-FIFO 模式

1、Stream-to-FIFO的選定((F_MODE[2:0] in FIFO_CTRL (2Eh) set to ‘011’),
2、FIFO 數(shù)據(jù)的讀取 PRESS_OUT_H (2Ah), PRESS_OUT_L (29h), and PRESS_OUT_XL (28h)
3、水閾中斷：(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滿了，老數(shù)據(jù)會(huì)被新數(shù)據(jù)更新。
4、如果觸發(fā)事件產(chǎn)生了，FIFO的狀態(tài)可以轉(zhuǎn)為FIFO的普通模式。觸發(fā)方式配置寄存器INTERRUPT_CFG (24h).

Bypass-to-Stream 模式

1、Bypass-to-Stream 模式的選定(F_MODE[2:0] in FIFO_CTRL (2Eh) set to ‘100’),
2、觸發(fā)方式設(shè)置INTERRUPT_CFG (24h). 利用觸發(fā)方式將ByPass 模式轉(zhuǎn)為Stream 模式，中斷源INT_SOURCE (25h) 的IA位來判斷

FIFO Mean 模式

1、FIFO Mean模式的選定(F_MODE[2:0] in FIFO_CTRL (2Eh) set to ‘110’),
2、FIFO Mean模式的特點(diǎn)：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、該模式下的數(shù)據(jù)讀取：
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：該模式下，不允許直接讀取FIFO的內(nèi)容。

Bypass-to-FIFO 模式

1、Bypass-to-FIFO 模式的選定(F_MODE[2:0] in FIFO_CTRL (2Eh) set to ‘111’),
2、觸發(fā)方式設(shè)置INTERRUPT_CFG (24h). 利用觸發(fā)方式將ByPass 模式轉(zhuǎn)為Stream 模式，中斷源INT_SOURCE (25h) 的IA位來判斷

寄存器表：

總上表中可以將寄存器總結(jié)如下：

**控制寄存器：**Control registers、Interrupt registers、FIFO configure registers、Resolution register
狀態(tài)寄存器：Status register
參數(shù)寄存器：Who am I register、Reference pressure 、Pressure threshold registers、Pressure offset registers
數(shù)據(jù)輸出寄存器：Pressure output registers、Temperature output registers

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