Design Of Magnetometer Digital Board Based On ARM

Proton magnetometer is a kind of static magnetic measuring instrument of high sensitivity based on the principle of Larmor precession effect and is widely used in the survey of geological environment,underground buried objects and geomagnetic anomaly detection,etc.At the beginning,the instrument’s sensor is put in an external magnetic field,and a large DC current passes through the coil.The coil generates a strong magnetic field so that the hydrogen proton magnetic moment is polarized along the direction of coil axis.Then,the high magnetic field is turn off.Hydrogen protons which are polarized in the solution perform the Larmor precession around the magnetic field.Finally,Hydrogen proton magnetic moment cutting induction coil frequency is called the Larmor precession frequency,There is a proportional relationship between the Larmor precession frequency and the external magnetic field.We achieve the proton magnetometer system based on ARM + CPLD system architecture.In this paper,JPM-3 proton magnetometer have been researched and innovated from three aspects: keyboard display module hardware circuit,digital module hardware circuit and digital module software program design.The instrument’s keyboard display module adopts the 19264 dot matrix LCD screen and improved key functions and layout.STM32F407ZGT6 is selected as the master chip and EPM1270T144I5N(one of the CPLD devices)is logic control devices in the digital board module hardware circuit.This paper designs the digital board hardware circuit of JPM-3 proton magnetometer system,which consists of digital board power supply module,STM32F407ZGT6 minimum system,FSMC parallel bus interface,data storage module,data transmission module and AD acquisition module.The software includes the preparation of peripheral chip drivers and the software program design.The master chip to achieve control of the various functional modules,data transmission and other functions,the instrument effective complete the various functions.Finally,the prototype of JPM-3 proton magnetometer is integrated and assembled by the actual circuit of each module.The prototype has the function of automatic tuned,the CPLD chip to collect the Ramall signal frequency into the magnetic field value,control the external FLASH memory magnetic field value data,the magnetic field value data through the data transmission module transmit to the computer.The results of the actual environment show that the prototype is highly reliable and can accurately obtain the parameters of the magnetic field to be measured.At the same time,two identical magnetic simulators were placed in the same field environment for magnetic field data test.Two identical JPM-3 proton magnetometers were used to measure the magnetic field value data to subtract the ambient noise.The sensitivity of the JPM-3 proton magnetometer is calculated as 0.34 n T.Performance close to the level of commercial magnetometer.