Do you realize that Freescale's JM Badge board can be designed into a seismometer ? The board is presented in FTF2008, distributed for free as name badge and starter kit for JM badge contest 2008. If Freescale can donate the board or sponsor the project, we can save people who are living in the seismic zone. I think Freescale can also benefit from seismometer business, since they can sell ColdFire microcontrollers, MEMS sensors, wireless modules (Zigbee). Because these products are quite cheap, the installation base could be huge.

Alternatively, you can use an empty beer bottle as the simplest seismometer.

In 2008 Great Sichuan Earthquake, at least 68,000 people were killed on May 12, 2008. The minor earthquakes become part of life for Sichuan people later on. Some local residents in Sichuan province invented a simple way to monitor the earthquakes, by putting an empty beer bottle upside down. It works so well, that the bottles were sold out. The engineers can help to design more precise instruments. Later on, I found a new seismometer SoC from a Japanese semiconductor supplier. The new SoC integrates an ARM processor and 24-bit Delta-Sigma ADC.

Theoretically, we can not predict an earthquake, we can only monitor and tell the probability of occurrence for earthquakes. Recently, earthquakes occur frequently in Japan, Indonesia, China and India. I try to search for something useful to monitor the earthquakes. At last I found a bunch of projects for seismic monitoring. I found conventional seismometer designs for research and education purposes, reference design from Cirrus Logic, free software iPhone Seismometer, QNC (Quake-Cather Network), and other alternative seismic monitoring. 

Professional Seismometers

Earthquake was very mysterious in ancient times. In the Han Dynasty, Zhang Heng invented the first seismic monitor and reported earthquakes successfully. The modem seismometer was invented in 1880. The precise seismometer is made up of sensors, high precision ADC, filter, communication subsystem and optional local storage. Cirrus Logic is one active company who offers some silicon products as well as complete reference design for this market sector. Actually, the key component is the signal conditional circuit (sensor + ADC). The rest digital part can be replaced by any microcontroller or DSP. No wonder why Japanese semiconductors suppliers have the motivation to design seismometer SoC. 

Alternatively, there are some other instruments which can be used in earthquake prediction. For example, Atmosphere Hydrogen Monitor is a great instrument to predict the possibility of an earthquake, which offers 30-40 days alarm period before it occurs. Before earthquake, the underground Hydrogen will be released to the atmosphere along with the broken the earth's surface.

I will cover this topic in other articles.

Consumer Seismometers

Only geographers are interested in the professional seismometers. People living in seismic zones are trying to build their seismometer with off-the-shelf components or devices. By searching internet, I found the following projects:

• In YouTube, I found a video clip from Tennesse SuperLab, demonstrating how to build a seismometer from an electric guitar pickup.
• IPhone Seismometer is free from iTunes Store, which collects shakes from two dimensions, analysis and draw on LCD screen, acting like a conventional Seismometer.
• Wii remote has wireless link with game console, it should be able to process and alarm. However I can not find any Wii software for seismometer, maybe anyone can build it later.
• Many legacy simple seismometer using 555 timers, pick up and buzzer.

The MEMS acceleration sensors are getting popular in many state-of-art consumer electronics devices, including Wii remote, GPS navigator, Robots, HDD, iPhone, iPod Touch, and Android G-Phone. These devices can be used as seismic front-end sensors without any extra hardware investments. The most promising platforms are smart phones and remote controls due to the largest user bases. They have technical limitations on precision and place directions. The sensors usually have two or three working axis with comparable sensitivities on each axis. 

The MEMS sensors in these consumer electronics are designed to detect strong movement in specific dimensions, such as detection device position changing between vertical and horizontal, or device dropping in HDD. These MEMS accelerometers can be used to detect ground motion. At the moment they are not sensitive enough (1g to 6g) to detect signals from distant earthquakes, however if an event happens nearby the data that they record can be quite useful.

Any single MEMS sensor in the consumer electronics can be disturbed by data corruption due to nearby subway, or unconscious misuse. As a result, a distributed seismic monitoring project, QCN is introduced by Stanford University. 

Distributed Monitoring System

QCN stands for Quake-Catcher Network Seismic Monitoring, which is a research project that uses Internet-connected computers to do research, education, and outreach in seismology. Currently only certain Mac (OS X) PPC and Intel laptops are supported -- recent ones which have a built-in accelerometer. Up to now, QCN detects earthquakes in southwest Germany, California, and Hawaii. According to their news, the detectable earthquakes are above 4.5M. Even the project can not offer too much precious data for research purpose, it still has great value for detection middle scale earthquakes.

Besides the Laptop computers, QCN also introduces a bare bone USB MEMS accelerators. It was made up of PIC18F24 and MEMS sensors from Microchip, at 50USD. People can purchase the sensor box online, install and connect to QCN servers. It is a good idea, but will you buy it can connect it online all the times?

Off-The-Shelf Products from Freescale

The USB MEMS kit reminds me of an interesting product from Freescale. In 2008, Freescale distributed its JM badge board in FTF2008 for free. The board is distributed as attendee’s name badge as well as the evaluation board for JM badge content 2008. In this board, it mounts MCF51JM128 ColdFire v1 128KB Flash microcontroller, MMA7260 3-axis low-g MEMS sensor, MC34673 Li battery charger IC, MPR083/084 capacitive touch sensor and display. It is not free now, but it is only 30/49USD on Freescale's web site. It is a perfect seismometer platform. All you need is monitor running on PC software. 

There are many ways to connect JM badge to remote servers. You can connect it to PC via USB-OTG on MCF51JM128, as same as QCN MEMS sensor. You also can connect a USB Ethernet adapter or USB WiFi to MCF51JM128, provided you have suitable USB host CDC ECM/EEM class driver. Alternatively, you can connect 2.5G/3G mobile module to MCF51JM128 through serial port. The USB port can also be used to connect a mobile module, if you have USB host CDC ACM class driver.

If the development for USB based Ethernet, mobile module takes too much effort, the Ethernet enabled ColdFire microcontroller (MCF5223X/5225X) can be used as well. Freescale also offers Zigbee stack, you can setup wireless bridge with MC1319x/20x, which was described in AN3577.

MCF51JM128 is compatible with 8-bit microcontroller MC9S08JM60. The 8-bit microcontroller has only 4KB RAM and up to 60KB flash memory, and it has only USB device interface. MCF51JM128 is much better is seismometer application due to its flexibility and processing power. Because ColdFire v1 has a MAC unit, so it can be used to process the acquired data before sending to the internet server. Freescale offers a complete DSP processing library for ColdFire microcontroller.

People may wonder why I am always talking, without offering a complete design to the public. The problem is money. No great idea can be true without financial support.

After all, if you are living in a seismic zone and have no interest in building a seismic monitor, just use a beer bottle as I mentioned. It can save your effort, and save your life and your family.

References
Creating a USB-to-Wireless Bridge with the MC1319x/20x and ColdFire Processors with USB OTG Module
Seismometer - Free software download
How to make a seismometer from an electric guitar
Turn Your Mac Book into a Seismometer, QCN
British Geological Survey
Bare bone USB MEMS three axis acceleration sensor

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