NTM88 Single-Axis Location Angle Project − Software User manual

PublishTime：2021-11-16

●This document describes the Tire Pressure Management System (TPMS) NTM88 Location Angle software version 2.0 designed to run on NXP's TPMS part NTM88H05,which includes a single-axis accelerometer X. The TPMS application software was developed using the CodeWarrior IDE. The purpose of the software is to monitor the angular position of a TPMS device attached to a rotating wheel and to start the transmission of a fixed length RF data packet at a given location such that the end of the packet arrives at the RF receiver when the TPMS device is at a pre-defined target angle location on the wheel. One, two, three or four target location angles can be specified in the user code and, depending on the wheel rotation speed, up to four RF data packets can be transmitted during one full wheel rotation. All TPMS location angle processing is based on accelerometer X data.
●The NTM88 Single-Axis project is closely related to the NTM88 Dual-Axis project. The only differences between the two projects are:
■Wheel rotation detection – In the Dual-Axis project, the compensated value of accelerometer Z and the centripetal acceleration are used to determine if the car is moving. In the Single-Axis project, function u8fWheelRotDet() determines if the car is moving by analyzing the compensated acceleration readings of accelerometer X.
■Low Pass Filters (LPF) implementation – In the Dual-Axis project there are four LPFs: LPF1, LPF2, LPF3 and LPF4. In the Single-Axis project there are three LPFs:LPF_4HZ, LPF_9HZ and LPF_20HZ. The bandwidths of the LPFs used in the two projects are similar but slightly different.
■LPF selection – For optimal performance when measuring the rotation period, LPF selection must be based on the wheel rotation speed. In the Dual-Axis project,accelerometer Z centripetal acceleration is used to estimate the rotation speed and select the LPF. In the Single-Axis project, a sequence of calls must be made to the period measurement function u8fXGetRotPeriod(LPFSel), with parameter LFPS elselecting one of the three LPFs. The sequence of calls is described in Section 5.
●The processing of accelerometer X sine waves to measure the rotation period and to calculate target angles is the same in both projects. The description of accelerometer X sine wave processing presented in the Dual-Axis project document NTM88 Dual-Axis Location Angle Project – Algorithms User Manual can be used as a reference for analyzing NTM88 Single-Axis project functions.

Brand of Product：	NXP
Part#：	NTM88 、 NTM88H05 More Part#
Product Category：	More
Application：	More
Data Type：	User's Guide More
Safety & Environment Standards：	More
Operating Temperature：	Please see the document for details
Qualification Grade：	More
Qualification Approval：	More
Package：
Language：	English Chinese Chinese and English Japanese
Date of Creation：	27 March 2020
Version Number：	Rev. 1
Data Encoding：	UM11361
Data Size：	149 KB

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