Selecting the correct reference crystal oscillator for the intelligent shared bike lock system

    Mobike - Mobike has launched a dockless bike sharing platform, creating a "dockless bike sharing" model dedicated to solving urban travel problems. Users only need to enter their license plate number on their WeChat service account or application to obtain a password and unlock their car anytime, anywhere. The new generation of shared bicycle intelligent lock supports positioning, GPS, remote control, GPRS, low-power Bluetooth chip connection, mobile phone control, unlocking, Mobike - Mobike shared bicycle is an intelligent hardware with a dockless borrowing and returning mode. This utility model solves the problem of borrowing and returning traditional piles. Borrowing and repaying this issue is both time-consuming and laborious. People can quickly rent and return Mobike bicycles through their smartphones, completing several kilometers of cycling at an affordable price.

    As the core of Mobike bicycles, the intelligent bike lock system aims to quickly locate and return the bike. The Mobike shared bike body lock integrates embedded chips, GPS crystal oscillator modules, and SIM cards to quickly locate nearby bicycles and monitor their specific location on the road. More importantly, the Mobike abandoned bike stake is fixed, allowing users to freely park in any government designated bike parking lot on the roadside. Users only need to place the bike lock, and the car can complete the operation.

How to choose the correct reference clock for the intelligent car lock system?

As the core part of the entire product, the reliability design of GPS/GPRS vehicle positioning and remote unlocking operation is the key to the normal operation of the network, and the stability of GPS/GPRS wireless system clock accuracy is based on fast communication and positioning speed and high reliability. The following are the two major requirements for the wireless RF reference clock Mobike smart bike lock system:

1) Wireless communication work requires a precise reference clock to enable fast and accurate communication of GPS positioning and GPRS control data, thus requiring the reference clock to have high frequency accuracy.

2) The Mobike smart bike lock includes a mechanical locking mechanism and an electronic unlocking mechanism, a rechargeable battery, and a small space on the left control board, so the product packaging requires a small clock.

How to choose the correct reference crystal oscillator for the intelligent car lock system?

The Epson TSX-3225 passive crystal has an initial frequency accuracy of up to ± 10ppm in the operating temperature range of+25 ℃ from 40 ° C to ± 85 ° C, and a clock accuracy of less than ± 10ppm in the temperature range of -20 ° C to+75 ° C. The frequency stability of long-term operation is better than ± 1ppm, much higher than the 5ppm of ordinary reference clock crystals. For GPS or GPRS systems, this is a good choice.

Main characteristics of TSX-3225 crystal oscillator:

• Frequency: 16MHz to 48MHz

• Package size: 3.2 x 2.5mm

• Storage temperature range: -55 ° C to+125 ° C

• Operating temperature range: -40 ° C to+85 ° C (+105 ° C)

Frequency tolerance: ± 10 x 10-6

• Load capacitance (CL): 7pF

Equivalent series resistance (ESR):

--60Ω（16.0MHz≤f_nom<21.0MHz）

--40Ω（21.0MHz≤f_nom≤48.0MHz）

TCXO temperature compensated crystal oscillator can make clock performance more accurate and stable, enabling the system to achieve higher sensitivity and maintain stability and consistency over a wide temperature range. TG-5006CJ/TG-5006CG TCXO temperature compensation crystal supports various levels of 1.8v/2.8v/3.0v/3.3v. It can flexibly adapt to different system levels; Frequency accuracy+1.5pp, operating within the range of -40 ° C to+85 ° C, with a stable frequency of 0.5ppm. The long-term stability is also maintained at 0.5ppm.

The main characteristics of TG-5006 crystal oscillator are:

• Output frequency range: 13-52MHz (TG-5006CJ/CG),

•VC-TCXO crystal oscillator, frequency control range ± 8.0~± 15.0ppm;

•The stability of frequency with temperature variation can reach ± 0.5ppm;

•The deviation after reflow soldering is less than ± 2.0ppm;

• Oscillatory start-up time of 2.0ms;

• Working temperature range -30 ℃~+85 ℃

•Lead free, compliant with RoHS standards.