Sports Game Station Exercise, entertainment and seizure

Shen Li, Ju Yingyi with Dr. Gabriela López and Dr. Sergio Rosales
Sports Game Station
Exercise, entertainment and seizure detection
Pediatric seizures epidemiology
Today, more and more people are participating in sports,
For some time, viewing television and video games has
pedaling a stationary bicycle or running on a treadmill to remain
been linked to photosensitive epileptic seizures. In Japan
fit. However, at the same time more children are forgoing
in December 1997, a televised Pokemon animated program
physical exercise and spending more time playing video games.
reportedly induced seizures in a number of children. The
Not only can the lack of exercise lead to weight gain, but the
investigation was narrowed down to a section of the show
visual nature of high-speed video games can lead to pediatric
that included a 15 Hz alternating red and blue flashing light.
seizures in children with photosensitive seizure disorder.
This tended to confirm previous reports that children with
The seizures can be induced by photic stimulation (flicker)
or by spatially periodic patterns[1]. These stimuli are found in
multiplayer online role-playing games, small handheld games,
video or television games and special game consoles[2].
Recognizing the risk, international organizations, including
the International Telecommunication Union (ITU) and the
International Organization for Standardization (ISO), have
begun to consider international guidelines for photic and
pattern stimulation in public media to help protect such
individuals[1], [2], [3], [4].
photosensitive seizure disorder are particularly affected by
flashes of very-long-wavelength monochromatic lights. In the
1999 study, “Photosensitive Epilepsy and Image Safety,” the
authors concluded that video game display flicker, intermittent
photic stimulation (IPS) at 50 Hz, may underlie the seizures
suffered by game players with photosensitive seizure
disorder[3], [5].
Reducing the risk
of pediatric seizures
Programmers can help reduce the risk of video game-induced
Freescale has built a wireless game controller demonstrator
seizures by eliminating such IPS instances as opposing changes
that combines a stationary exercise bicycle with video game
in luminance between pairs of flashing lights and transition to
technology to help people stay fit while playing their games.
or from saturated red, and by limiting flashing sequences to no
What’s more, by integrating a ZigBee transceiver and a
more than three per second.
three-axis low-g microelectromechanical system (MEMS)
accelerometer, the Freescale Sports Game Station (SGS) is
designed to detect evidence of conditions such as a pediatric
seizure and wirelessly transmit an alert signal to parents or other
To help players lessen the risk of seizure, the Epilepsy
Foundation recommends:
• Sitting at least two feet from the screen in a well-lit room.
caretakers. The concept is designed to help make video game
• Reducing the brightness of the screen.
playing healthier and safer.
• Not allowing children to play video games if they are tired.
• Taking frequent breaks from the games and looking away
from the screen every once in a while. Do not close and open
eyes while looking at the screen as blinking may facilitate
seizures in sensitive individuals.
• Covering one eye while playing, alternating the covered eye
at regular intervals.
• Turning the game off if strange or unusual feelings or body
jerks develop.
Sports Game Station 21
Freescale Sports Game Station:
combining exercise, entertainment
and seizure detection
SGS System Overview
Station Diagram
TRX MC13192
USB Connectivity
USB Driver
Station Board
Figure 1
SGS has two parts, one is a station and the other is an
endpoint. On the station board (Figure 1), there is a 32-bit
MCF51JM128 microcontroller (MCU) based on the V1 ColdFire®
core with integrated USB On-The-Go and an MC13192 shortrange, low-power 2.4 GHz industrial, scientific and medical
(ISM) band transceiver.
Endpoint Board
Stationary Bicycle
Figure 3
USB keyboard, enabling many popular keyboard or joystick
controlled video games to use this system as its controller. For
Endpoint Diagram
different game controllers, this platform is able to use different
TRX MC13192
Ultra-Low-Power MC9S08QE32
Battery Supply
Figure 2
The endpoint board (Figure 2) includes an ultra-low-power
8-bit MC9S08QE32 (S08QE32) main control chip, an MC13192
low-power 2.4 GHz wireless transceiver and the MMA7260QT
3-axis, low-g MEMS accelerometer.
movement sensors, simple buttons or joysticks. For instance,
Freescale’s 3-axis low-g MMA726x accelerometers are already
used for tilt detection in some well-known PC games. For
stationary bicycles, the speed sensor and direction control
keys can be adopted. For a wrestling game, a joystick can be
used as a direction controller and the accelerometers sense the
punching and kicking motions.
Using the endpoint sensor
to detect seizures
Adding significant value to the Freescale’s SGS, the endpoint
can be used to provide some peace-of-mind for players with
photosensitive seizure disorder. The same endpoint hardware
can be used, requiring only a different software implementation
As part of the complete system (Figure 3), the endpoint is
that can recognize a seizure event. A seizure may occur when
attached to the player’s body or activity equipment to record
a brief, strong surge of electrical activity affects part or all
movement. The accelerometer senses motion (specific human
of the brain. Seizures can last from a few seconds to a few
action) and converts the action to an analog electronic signal.
minutes and can exhibit many symptoms, from blank staring, lip
The MCU (S08QE32) reads the analog signal and converts it
smacking or jerking movements to more dangerous convulsions
to a suitable keyboard key value. After that, the MCU sends
and loss of consciousness.
the key value to the wireless transceiver through the SPI port
and directs the wireless transceiver to transmit the data to the
station. When the transceiver on the station board receives a
key value data packet, it alerts the MCU (MCF51JM128), which
reads the data through the SPI port and sends the key value
to a PC via a USB cable. Thus, the PC can recognize human
actions as a keyboard value.
To detect evidence of conditions such as a seizure, a reliable
algorithm is necessary. This special algorithm must be designed
using enough samples of seizure waveforms (caused by
jerking body movements) gathered by the accelerometer to
ensure exceptional accuracy. Once the seizure information is
transmitted to the station and, in turn, sent to a computer, a
software program running on the PC can alert parents through
In this example, the endpoint acts as a sensor that transmits
an automatic text message to their cell phones or a buzzer
activities and motions to the station while the station acts
alarm in the game console that an unexpected seizure has
as a USB human interface device class (USB HID) keyboard
occurred. This data could also be submitted to a neurologist to
device. When connected to a PC, it is recognized as a simple
verify the waves and confirm any abnormal activity.
Sports Game Station 22
Long battery life
Because the SGS endpoint is a wireless game controller, power
SMAC is an uncomplicated software protocol based on the
consumption is an important design consideration. All three
IEEE® 802.15.4 protocol that works with Freescale’s transceivers
of the primary components exhibit exceptional low-power
with 8-bit MCU control. It is free of charge from Freescale and is
performance: the ultra-low-power S08QE32 MCU (about
intended to be used for fast product development and system
0.4 µA in STOP mode), MC13192 wireless transceiver and the
evaluation. SMAC is simple and easy to use because it implements
MMA7260 low-g accelerometer (about 3 µA in sleep mode).
neither the full ZigBee stack nor the complete 802.15.4 layer.
In addition, if there is no signal detected by the sensor within
SMAC is ideal for low-cost applications that require basic
several minutes, the endpoint itself will enter sleep mode to
primitives, such as transmit, receive and power and channel
conserve battery life.
selection. For more details on SMAC, please refer to the stack
reference manual (search for SMACRM) at
Software Overview Diagram
SGS Station
SGS Endpoint
AD Val Key Val
Hardware Abstract
Hardware Abstract
Figure 4
SGS firmware
Freescale has the necessary technology to develop a
sophisticated gaming system to provide entertainment,
promote fitness and detect photosensitive seizures. Wireless
transceivers (MC1319x/1320x family) and free stacks (SMAC),
accelerometers (MMA726x family), low-power 8-bit MCUs
(S08QE family) and high-performance, connectivity-enabled
ColdFire MCUs (MCF51JM family) are the key elements used
to build the SGS system. Technical support is also available,
and Freescale designers regularly consult with customers
and medical doctors to develop more new products that can
improve the quality of life.
[1] “Photic- and Pattern-Induced Seizures: Expert Consensus
of the Epilepsy Foundation of America Working Group,”
It is easy to program the firmware for both the station and
Graham Harding, Arnold J.Wilkins, Giuseppe Erba, Gregory
endpoint (Figure 4). The station includes a USB driver,
L. Barkley and Robert S. Fisher, Epilepsia, 46(9):
1423–1425, 2005
USB-HID keyboard protocol and simple multimedia access
controller (SMAC) protocol. (For more details on the USB driver
[2] “Massively Multiplayer Online Role-Playing Game-Induced
and USB-HID class for ColdFire MCUs, please refer to the
Seizures: A Neglected Health Problem in Internet Addiction,”
CMX_USB-LITE stack, available at
Yao-Chung Chuang, CyberPsychology & Behavior,
For the endpoint, a SMAC and a simple algorithm translates
tilt, movement, direction and speed signals into a keyboard or
August 1, 2006, 9(4): 451–456
[3] “Game-Related Seizures Presenting with Two Types of
Clinical Features,” Yao-Chung Chuang, Wen-Neng Chang,
joystick where values are needed. The endpoint’s MMA7260QT
Tsu-Kung Lin,Cheng-Hsien Lu, Shang-Der Chen, Chi-Ren
accelerometer outputs variable voltage levels to X, Y and Z
Huang, Seizure (2006) 15, 98–105
output pins when it detects a tilt, movement or acceleration.
The ADC module in the S08QE32 MCU reads the voltage
[4] “Mechanisms of Video-Game Epilepsy,” F. Fylan, G. F. A.
level outputs and converts them to digital values that can be
Harding, A. S. Edson and R. M. Webb, Epilepsia,
recognized as movement activity. And with the SMAC
4O(Suppl. 4): 28–30, 1999
protocol, any simple data packet can be easily sent or
[5] “Video-Game Epilepsy: A European Study,” D. G. Kasteleijn-
received effectively.
Nolst Trenité, A. Martins da Silva, T. S. Ricci, C. D. Binnie,
G. Rubboli, C. A. Tassinari and J. P. Segers, Epilepsia,
4O(Suppl. 4): 70–74, 1999
Ju Yingyi is a ColdFire application engineer with expertise in SMAC, FAT/FAT32 and microWindows (GUI). Shen Li is also a
ColdFire application engineer. He has a master’s degree in communication and information systems and has been with Freescale
for almost five years. Gabriela López-Armas, M.D., is a postgraduate resident in biomedical sciences at the Laboratory of
Neuroscience of the Centro de Investigación Biomédica de Occidente (Western Biomedical Research Centre) belonging to the
Social Security Mexican Institute. Dr. Rosales is a pediatric surgeon and holds a Ph.D. in neurodegenerative disorders. His research
has been recognized in the Alzheimer Association for entrepreneur activities in this field.
Sports Game Station 23
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