MED-EKG
User Manual
Rev. 1.0
Freescale Semiconductor Inc.
Contents
1 Overview ......................................................................................................................................................3
2 Reference Documents ..............................................................................................................................4
3 Hardware Features ...................................................................................................................................4
3.1 System Power ....................................................................................................................................................................... 4
3.2 Debug Interface ................................................................................................................................................................... 4
3.3 Medical Connector.............................................................................................................................................................. 4
3.4 Mechanical Form Factor .................................................................................................................................................. 5
3.5 External Electrodes Connector ..................................................................................................................................... 5
3.6 Slider Electrodes ................................................................................................................................................................. 6
4 Jumper Table ..............................................................................................................................................6
MED-EKG User Manual
Page 2 of 7
1 Overview
The Medical EKG Module (MED-EKG) is a low cost development board that allows users to rapidly
prototype electrocardiogram (EKG/ECG) applications. Users can choose to develop EKG/ECG
applications using the external analog components or by using the Flexis MM microcontroller’s on-chip
analog modules or a mixture of both. MED-EKG is designed to work with the TWR-MCF51MM module
and TWR-S08MM128 module. The EKG/ECG software demonstration and step-by-step lab guide is
available in the both the Tower System TWR-MCF51MM-KIT and TWR-S08MM128-KIT or from
www.freescale.com
NOTE:
TWR-MCF51MM-KIT features the 32-bit MCF51MM256 microcontroller and the TWR-
S08MM128-KIT features the 8-bit MC9S08MM128 microcontroller. Peripherals between these two 32-
bit and 8-bit MCUs are either identical or compatible; they are called the Flexis devices.
The following list summarizes the features of the MED-EKG board:
•
Freescale Tower System compliant and small form factor
•
External connector to TWR-S08MM128 and TWR-MCF51MM MCU modules
•
Includes the MC56F8006 DSC used for signal conditioning
•
Electrodes embedded in development board for easy EKG signal detection using fingertips
•
Open connector for any type of EKG electrodes for additional precision
•
JTAG-ONCE connector for DSC programming
•
Different jumper configurations to allow various signal conditions
•
Low power
Figure 1. MED-EKG Block Diagram
Integrated
Electrodes
(left, right and
reference
sliders)
JTAG/ONCE
Compensation
Medical Connector
3.3 V
Low-pass
filter
14-pin header
PWM
IIC bus
External
INA
External
electrodes
connector
Internal MM
amplifiers (INA
configuration)
Analog
band-pass
filter
MM
16-bitADC
Internal
amplifiers
In/Out
External
amplifier
ADC
MC56F8006
16-bit Digital
Signal Controller
3.3 V
Analog
band-pass
filter
Internal
MM
amplifier
Analog
notch
filter
External
amplifier
Low-pass
filter
MM
12-bit DAC
Reference
voltage
1,6 V
Compensation
Freescale Silicon
External Connectors
Interface Circuits
Jumper configurations
INA
Instrumentation Amplifier
Power
MED-EKG User Manual
Page 3 of 7
2 Reference Documents
The documents listed below are available online. Refer to
www.freescale.com/tower
or
www.freescale.com/medical
for the latest revisions of these documents.
•
MED-EKG Schematics
•
Quick Start Guide for TWR-S08MM128
•
Quick Start Guide for TWR-MCF51MM
•
TWR-MCF51MM-KIT and TWR-S08MM128-KIT Labs
3 Hardware Features
This section provides more details about the features and functionality of the MED-EKG.
3.1 System Power
The MED-EKG is powered by the default trough connector J1, but can be also powered by the JTAG-
ONCE port. Do not apply both power sources at the same time.
NOTE:
Power switch is controlled by the MCF51MM256 or MC9S08MM128 pin PTE7 from the
corresponding Tower System MCU module. To turn on the MED-EKG module in your software, make
sure to set PTE7 pin to output low (active low). To turn off, set PTE7 to output high. This has already
been done in the MED-EKG demonstration software in the TWR-MCF51MM-KIT or TWR-S08MM128-
KIT.
3.2 Debug Interface
The included DSC is factory programmed with firmware for digital filtering (a band-pass filter and a
notch filter), however it can be reprogrammed using an external JTAG-ONCE interface (USB-TAP) for
user specific applications. It can be connected on header J10.
3.3 Medical Connector
Header J1 (2x10 pins) of MED-EKG provides connectivity with either the TWR-MCF51MM or the TWR-
S08MM128 board through the medical connector. It allows the use of internal OPAMPs, TRIAMPs, ADC
and DAC of Flexis MM 32-bit or 8-bit microcontrollers to implement the requirement of signal
conditioning. Pin 3 and 4 can also be used to send DSC filtered data to the target Tower MCU. Table 1
shows the signal present in each pin of medical connector. Please refer to TWR-MCF51MM-KIT or the
TWR-S08MM128-KIT LAB1 MED-EKG DEMO for instructions on assembling with the Tower System.
MED-EKG Signal
VDD(3.3V)
ECG_IIC_SDA
MM_AdcEcgSignal
MM_AdcBaseline
OUT1
Pin
1
3
5
7
9
2
4
6
8
10
MED-EKG Signal
GND
ECG_IIC_SCL
GND
MMDac
OUT2
MED-EKG User Manual
Page 4 of 7
INP1-
INP1+
VINP1
VINN1
TRIOUT1
11
13
15
17
19
12
14
16
18
20
INP2-
INP2+
VINP2
VINN2
TRIOUT2
Table 1. Medical Connector 2x10 Pin Header Connections
3.4 Mechanical Form Factor
The MED-EKG is intended to be used as an expansion of the TWR-S08MM128 and TWR-MCF51MM
boards. It’s designed for the Freescale Tower System and complies with the electrical and mechanical
specifications that are described in
Freescale Tower Electromechanical Specification.
3.5 External Electrodes Connector
The external electrodes connector is labeled as J12 on the MED-EKG module. This connection yields
less noise and provides the best way to prototype your EKG application instead of using the on-board
sliders contact. The user can connect a 3 lead cable (2 electrodes and 1 ground) via J12 header and use
external electrodes. Freescale does not provide this lead due to regulations in different countries. The
user has to purchase it separately. This board was tested with Welch Allyn ECG Lead Wires for Atlas
Monitor, 3-lead AHA. Figure 2 shows a connection example with external electrodes.
Figure 2. External Electrodes Connection Example
MED-EKG User Manual
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