MOD-EKG development board
User's manual
All boards produced by Olimex are ROHS compliant
Document revision B, December 2016
Page 1 of 17
INTRODUCTION:
MOD-EKG is an implementation of the hardware design proposed by Texas In-
struments in their document “Heart-Rate and EKG Monitor Using the MSP430FG439”
(document name “slaa280a”). MOD-EKG is an open-hardware, open-software project.
The user places his index fingers and thumbs at the metallic pads of the board and the
heartbeat rate per minute gets displayed on the LCD. In addition, the application outputs
a digital data stream to a serial data interface which allows you to display EKG wave-
form on a PC. The serial interface is available at the UEXT connector. Using our serial
↔ USB adapter. A connection between the PC and MOD-EKG can be achieved by us-
ing our adapter – MOD-USB-RS232 that converts the serial interface to USB, and vice
versa.
An electrocardiogram (ECG), also called an EKG, is a graphic showing the
voltage generated by the heart muscle during a heartbeat. In this application, the EKG
waveform is used by the MCU to measure the heartbeat rate. Because heartbeat calcula-
tion is the major focus the electrodes are simplified to two points for collecting data, one
for the right hand and the other for the left hand.
BOARD FEATURES:
Microcontroller:
MSP430FG439
EKG amplifiers with
INA321EA
14-pin 0.1” step JTAG connector for direct microcontroller access via
MSP430 debugger to debug the software or to power the board
UEXT connector that allows easier connection to other boards
Custom LCD display
3V CR2032 Lithium coin battery holder
Extension rows of pinholes for all microcontroller ports – with no plastic
connectors placed
No additional electrodes required! Right and left hand contact board-
mounted electrodes – HR1 and HR2
Two status LEDs
Two user buttons
A switch to alternate between “battery” and “UEXT” power supply
Based on Texas Instruments application note SLAA280a
FR-4, 1.5 mm, red soldermask, white component print
Dimensions: (3.0 x 2.8)" ~ (76 x 71)mm
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ELECTROSTATIC WARNING:
The MOD-EKG board is shipped in protective anti-static packaging. The board must
not be subject to high electrostatic potentials. General practice for working with static
sensitive devices should be applied when working with this board.
BOARD USE REQUIREMENTS:
In order to set up the PIC32-RETROBSD board optimally one or more additional items
may be needed. They might be generally placed in two categories:
Required
– items
that are needed in order to achieve minimum functionality;
Recommended
– items that
is good to have in order to be able to interact with the most important of the features of
the board.
a) Required items:
- A source of power; preferably a battery. MOD-EKG can take power from a number
sources:
1) +3V CR2032 Lithium battery placed in the battery connector at the back –
when switch BAT/UEXT is in position BAT.
2) JTAG deubgger placed in the JTAG connector – when jumper P_IN is closed
and P_OUT is opened.
3) Pins #1 (3.3V) and #2 (GND) of the UEXT connector – when switch
BAT/UEXT is in position UEXT; you can also supply 3V from a battery to these
pins
The power supply source gets selected by changing jumpers P_IN and P_OUT
and using the BAT/UEXT switch.
IMPORTANT: MOD-EKG is a sensitive board and glitches or noises in the power
supply lines might affect the readings. Even if the USB ports and the power supply unit
are of good quality, there is still parasitic capacitance between the human body and
mains power line, which affects the readings. Be sure to test with a 3V battery – either
insert a good CR2302 coin battery directly in the connector at the back of MOD-EKG
or attach a 3V battery to the UEXT. If you wish to power the board from the JTAG or
external power supply make sure there is galvanic isolation or good filtering between
the power supply and the MOD-EKG board. For example, if you want to isolate your
JTAG debugger from the mains power influence you can use our USB-ISO product
(between the computer's USB port and the JTAG debugger).
b) Recommended items:
- serial to USB adapter board – to connect to a personal computer; you can use a
number of our low cost solutions, for example,
BB-340CH
or
MOD-USB-RS232;
note
that the examples for computer connection use MOD-USB-RS232
- MSP430-compatible debugger with 14-pin (2 x 7) 0.1” step connector; if you want a
compatible low-cost Olimex product consider
MSP430-JTAG-TINY-V2
or
MSP430-
JTAG-ISO-MK2
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PROCESSOR FEATURES:
MOD-EKG board uses ultralow power microcontroller MSP430FG439 from Texas
Instruments with the following features:
Low Supply-Voltage Range, 1.8 V to 3.6 V
Ultralow-Power Consumption:
Active Mode: 300 μA at 1 MHz, 2.2 V
Standby Mode: 1.1 μA
Off Mode (RAM Retention): 0.1 μA
Five Power Saving Modes
Wake-Up From Standby Mode in Less Than 6 μs
16-Bit RISC Architecture, 125-ns Instruction Cycle Time
Single-Channel Internal DMA
12-Bit A/D Converter With Internal Reference, Sample-and-Hold and Autoscan
Feature
Three Configurable Operational Amplifiers
Dual 12-Bit D/A Converters With Synchronization
16-Bit Timer_A With Three Capture/Compare Registers
16-Bit Timer_B With Three Capture/Compare-With-Shadow Registers
On-Chip Comparator
Serial Communication Interface (USART), Select Asynchronous UART or
Synchronous SPI by Software
Brownout Detector
Supply Voltage Supervisor/Monitor With Programmable Level Detection
Bootstrap Loader
Serial Onboard Programming, No External Programming Voltage Needed
Programmable Code Protection by Security Fuse
Integrated LCD Driver for Up to 128 Segments
60KB+256B Flash Memory
2KB RAM
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BLOCK DIAGRAM:
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