NBP8 datasheet(21/58 Pages) NXP

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NXP Semiconductors

NBP8

Battery pressure monitor sensor

Time

aaa-037675

Debounce_cnt is equeal to 6 so

we calculate Slope, and

Slope > Slope_T => STF flag

is raised

Debounce_cnt is equal to 6 so we calculate

Slope, and Slope < Slope_T

=> STF flag is not raised, Debounce_cnt set to 0,

Pref set to Pcurrent = 170 and t = 0

100

150

200

250

300

150 200 250 300 350 400 450 500 550 600

Slope 1 = [(170-100)*128]/(5+1) = 1493

Slope 2 = [(320-170)*128]/(7+1) = 2400

650 700 750 800 850 900 950

100

Pcurrent value

User configuration:

Debounce_T = 5

Min_T = 5

Slope_T = 2000

Pressure

Unit for indication only

110 105 100 120 130 135 150 160 170 180 200 230 250 200 270 300 320

Deb_ST_cnt value

t value

100

PrefSt value

100 105 100 100 100 100 100 100

170 170 170 170 170 170 170

Figure 14. Example of slope threshold algorithm flow

6.5.5 Description of the pressure FIFO

The last twelve pressure measurements are stored in the pressure FIFO. Pressure

measurements are stored on two bytes, so the FIFO depth is 24 bytes. The FIFO is

implemented as a rolling buffer: the most recent pressure measurement overwrites the

oldest one. An 8-bit index INDFIFO holds the value of the last address written.

The FIFO starts at address $0076 and ends at address $008D. Addresses that have not

yet been written contain the value 0x00. Measurements are written from the lower to the

higher addresses, Most Significant Byte first. When the highest address has been written,

the next sample is written at the lowest address.

Figure 15 shows how the program fills FIFO, for the first 25 samples. The index value

after the sample Pn - the nth sample - has been written is also indicated.

NBP8

All information provided in this document is subject to legal disclaimers.

Product data sheet

Rev. 2.4 — 11 March 2022

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