ET2020/EFA
15
www.oxleygroup.com/eti
ODCSM40539/2/2005
Oxley Developments Company Ltd
Email: sales@oxley.co.uk
Tel: +44 (0)1229 483226
Oxley Group Australia Pty Ltd
Email: sales@oxleygroup.com
Tel +61 (0) 2 9967 9488
Oxley Inc.
Email: sales@oxleyinc.com
Tel: +1 (203) 488 1033
Elapsed Time Indicator ET2020/EFA
Features
EEPROM non-volatile memory.
10 years data retention.
Low power, 10 mW typical.
Serial and parallel outputs.
Microprocessor compatible.
Non-volatile text storage and recall.
Military specifications.
For ordering information see page 22.
Construction
The 18 pin ceramic dual-in-line package is assembled
using thick film chip hybrid technology, ensuring
suitability for military, avionic, and industrial applications
where severe environmental conditions maybe
encountered.
Note: The Test pin is provided for factory purposes
only and should be left unconnected.
1
2
3
4
5
6
7
8
910
11
12
13
14
15
16
17
18
VAUX
Output Select
Request Time
Count
Tx
Rx
Data Valid
Test
VSS
VCC
D7
D6
D5
D4
D3
D2
D1
D0
Pin 18
Pin 1
16.2 mm
(0.638") max
5 mm (0.197") nom
5 mm (0.197") nom
3 mm (0.600") nom
30.4 mm (1.197") nom
0.56 mm
(0.022") max
Pitch 2.54 mm
(0.100")
15.24 mm
(0.600") CRS
0.25 mm
(0.010") nom
ET2020/EFA
16 www.oxleygroup.com/eti
ODCSM40539/2/2005
Oxley Developments Company Ltd
Email: sales@oxley.co.uk
Tel: +44 (0)1229 483226
Oxley Group Australia Pty Ltd
Email: sales@oxleygroup.com
Tel +61 (0) 2 9967 9488
Oxley Inc.
Email: sales@oxleyinc.com
Tel: +1 (203) 488 1033
Application Circuit Diagrams
Typical application ODCSM40539/2/2005circuit diagrams are shown below for serial and parallel
interrogation modes. The internal timer is activated whenever the 5 V power supply is applied. No
additional timing control circuitry is required. The total elapsed time is accumulated in the internal
non-volatile memory for interrogation through either the serial or parallel interfaces.
Serial Mode
Parallel Mode
VAUX
Output Select
Request Time
Count
Tx
Rx
Data Valid
Test
VSS
VCC
D7
D6
D5
D4
D3
D2
D1
D0
RS 232
Level
Shifter
0 Volts
ET2020/EFA
TX
RX
5 Volt Equipment Supply
VAUX
Output Select
Request Time
Count
Tx
Rx
Data Valid
Test
VSS
VCC
D7
D6
D5
D4
D3
D2
D1
D0
0 Volts
ET2020/EFA
5 Volt Equipment Supply
Data Valid
Request
Time
External
Control
Circuitry
8 bit - Tristate
Data Bus
ET2020/EFA
17
www.oxleygroup.com/eti
ODCSM40539/2/2005
Oxley Developments Company Ltd
Email: sales@oxley.co.uk
Tel: +44 (0)1229 483226
Oxley Group Australia Pty Ltd
Email: sales@oxleygroup.com
Tel +61 (0) 2 9967 9488
Oxley Inc.
Email: sales@oxleyinc.com
Tel: +1 (203) 488 1033
Power Supply
A single 5 Volt power supply, Vcc is required for operation. A separate power supply input Vaux is also
provided for energisation from a second power source. A blocking diode is internally connected to prevent
current from Vaux powering parent equipment connected to Vcc. This provides cold read facilities during
failure of parent equipment or when it is powered down.
Interrogation
The ETI can be interrogated in either serial or parallel format. The OUTPUT SELECT (OS) input is used
for selection of interrogation mode.
Serial Data (Output Select = 0)
Serial data transfer uses two pins, Rx (receive data), and Tx (transmit data). Together with a signal
common, these lines constitute a 3 wire serial communication interface utilising a standard non-return to
zero (NRZ), data format. Direct interface can be made with integrated circuit UART devices. The signals
can also be level shifted to conform to RS232 requirements.
The Rx and Tx signals must meet the following requirements:-
1A High level indicates logic 1 (5 V) and a low level indicates logic 0 (0 V).
2The Rx input must be in a high state prior to reception of data.
3A start bit, (logic 0), is transmitted/received indicating the start of a message.
4Bytes of data are transmitted/received least significant bit first.
5A stop bit, (logic 1), in the 10th bit position indicates transmission/reception of a byte is complete.
6Baud rate: 9600 b/s
Data bits: 8
Start bits: 1
Stop bits: 1
Parity: None
To initiate transmission of serial elapsed time/pulse count data a unique two character ASCII command
“ET” must be received at the Rx input. Following reception of a valid “ET” command the ETI will output the
elapsed time message on the Tx output. If an invalid command is received an ASCII carriage return
character, (0D hex), is transmitted.
ET2020/EFA
18 www.oxleygroup.com/eti
ODCSM40539/2/2005
Oxley Developments Company Ltd
Email: sales@oxley.co.uk
Tel: +44 (0)1229 483226
Oxley Group Australia Pty Ltd
Email: sales@oxleygroup.com
Tel +61 (0) 2 9967 9488
Oxley Inc.
Email: sales@oxleyinc.com
Tel: +1 (203) 488 1033
Serial Elapsed Time Interrogation
Bytes 1 and 12 are ASCII carriage return characters. Bytes 2 to 9 represent the elapsed time reading and
are ASCII characters. Byte 2 is the most significant digit. Byte 7 is always “.” and byte 11 “H” denoting units
of hours. Elapsed time measurement is suspended for typically 300 ms during serial data output.
Parallel Data (Output Select = 1)
Parallel elapsed time/pulse count interrogation is initiated by holding the REQUEST TIME input at logic 0
for time tRT or until the positive edge of DV(1). The elapsed time/pulse count time information then appears
sequentially in 3 bytes on outputs D0-D7. Data is synchronised with pulses which appear on the DATA
VALID (DV) output. Each byte represents a 2 digit BCD number. Outputs D7-D4 represent the most
significant digit, outputs D3-D0 represent the least significant digit. D0-D7 are tri state outputs suitable for
direct connection onto a high impedance data bus.
Parallel Text Interrogation
Parallel text interrogation is initiated by holding the REQUEST TIME input at logic 0 for the time tRTT or
until the positive edge of DV(4). Following the 3 bytes of elapsed time/pulse count information, the ASCII
text appears on outputs D0-D7 synchronised with DATA VALID pulses DV(4) to DV(53). To request
elapsed time information only, the REQUEST TIME pulse width should not exceed tRT max. Elapsed time
measurement is suspended for typically 300 ms during parallel data output.
BYTE 123456789101112
CHARACTERcr00000. 00 Hcr
HEX 0D30303030302E303020480D
VCC
Rx
Tx
“E” “T”
“CR” “H” “CR”
900 ms min 6 ms max
1 ms min
Byte
1
Byte
2
Byte
3
Byte
4
Byte
5
Byte
6
Byte
10
Byte
11
Byte
12
ET2020/EFA
19
www.oxleygroup.com/eti
ODCSM40539/2/2005
Oxley Developments Company Ltd
Email: sales@oxley.co.uk
Tel: +44 (0)1229 483226
Oxley Group Australia Pty Ltd
Email: sales@oxleygroup.com
Tel +61 (0) 2 9967 9488
Oxley Inc.
Email: sales@oxleyinc.com
Tel: +1 (203) 488 1033
BCD Parallel Output
During DV(1) the digits represent HOURS x 103 and HOURS x 102.
During DV(2) the digits represent HOURS x 101 and HOURS x 100.
During DV(3) the digits represent HOURS x 10-1 and HOURS x 10-2.
Parameter Description Min Max Units
tIInitialisation time 900 ms
tRT Request time pulse width for time information only 6 12 ms
tRTT Request time pulse width for time & text information 16 ms
tSDV Time to set up 1st data valid 6 ms
tDV Data valid pulse width 90 110 µs
tPDV Period of data valid 4.99 5.01 ms
tOT Total bus active time 264 ms
tOET Total bus active time, elapsed time
only output
15 ms
tZDV Time from end of Z state to 1st DV 175 typical µs
tDS Data set up time 90 typical µs
tRTP Request time repetition period 300 ms
HIGH IMPEDANCE
HIGH IMPEDANCE
HIGH IMPEDANCE
HIGH IMPEDANCE
HIGH IMPEDANCE
HIGH IMPEDANCE
HIGH IMPEDANCE
HIGH IMPEDANCE
READING = 1234.56 "T" "E" "X" "T" "$"
HIGH IMPEDANCE
HIGH IMPEDANCE
HIGH IMPEDANCE
HIGH IMPEDANCE
HIGH IMPEDANCE
HIGH IMPEDANCE
HIGH IMPEDANCE
HIGH IMPEDANCE
HIGH IMPEDANCE
D0
DV
RT
Vcc
D1
D2
D3
D4
D5
D6
D7
ZDV
t
RTP
t
DS
t
OT
t
I
t
OET
t
RTT
t
RT
t
DV
t
PDV
t
SDV
t
DV(1) DV(2) DV(3) DV(4) DV(5) DV(6) DV(7) DV(53)
ET2020/EFA
20 www.oxleygroup.com/eti
ODCSM40539/2/2005
Oxley Developments Company Ltd
Email: sales@oxley.co.uk
Tel: +44 (0)1229 483226
Oxley Group Australia Pty Ltd
Email: sales@oxleygroup.com
Tel +61 (0) 2 9967 9488
Oxley Inc.
Email: sales@oxleyinc.com
Tel: +1 (203) 488 1033
User Programmable Text
50 bytes of EEPROM are provided for user entry and storage of 50 characters of text information. The text
may record, for example, maintenance and warranty status of parent equipment. Text may be rewritten as
often as required and can be read by both serial and parallel outputs. Text can only be entered serially.
Text Entry
Text entry can only be made whilst in serial mode and is initiated by detection of the ASCII “IX”: command
at the Rx input. Up to 50 ASCII text characters should then be input, terminated either by a carriage return
or by entry of the 50th character. Text entered will overwrite previously stored text.
Serial Text Input
Serial Text Interrogation
Serial text interrogation is achieved by using the ASCII “OX” command.Serial Text Output
VCC
Rx
Tx
“I” “X”
“CR”
900 ms min 5 ms min
1 ms min
Text
1
Text
2
Text
3
Text
50
0.1 ms min 0.2 ms typical
VCC
Rx
Tx
“O” “X”
“CR”
900 ms min 6 ms max
1 ms min
Text
1
Text
2
Text
50
0.1 ms typical
“CR”
ET2020/EFA
21
www.oxleygroup.com/eti
ODCSM40539/2/2005
Oxley Developments Company Ltd
Email: sales@oxley.co.uk
Tel: +44 (0)1229 483226
Oxley Group Australia Pty Ltd
Email: sales@oxleygroup.com
Tel +61 (0) 2 9967 9488
Oxley Inc.
Email: sales@oxleyinc.com
Tel: +1 (203) 488 1033
Typical Drive Current Graph
7.0
6.0
5.0
4.0
3.0
2.0
1.0
ID (mA)
0.5 1.0 1.5 2.0
VCC - VOH (volts)
ET2020/EFA
22 www.oxleygroup.com/eti
ODCSM40539/2/2005
Oxley Developments Company Ltd
Email: sales@oxley.co.uk
Tel: +44 (0)1229 483226
Oxley Group Australia Pty Ltd
Email: sales@oxleygroup.com
Tel +61 (0) 2 9967 9488
Oxley Inc.
Email: sales@oxleyinc.com
Tel: +1 (203) 488 1033
Characteristics
Ordering Information
When ordering please state Type No. and quantity required.
Operating temperature range -55°C to 125°C
Storage temperature range -55°C to 125°C
Supply voltage, VCC 4.5 to 5.5 V d.c.
Supply voltage, VAUX 4.0 to 5.5 V d.c.
Supply current 2 mA typical, 4 mA max.
Timing resolution 0.01 hours
Timing accuracy ± 0.1%
Capacity (PARALLEL MODE) 104 hours /106 pulses
Capacity (SERIAL MODE) 105 hours /107 pulses
VOH, Output logic 1 VCC-1 to VCC Iload <1ma
VOL, Output logic 0 VSS to 0.4V
VIH, Input logic 1 0.8 x VCC to VCC
VIL, Input logic 0 VSS to 0.2 x VCC
IZ, High Z leakage current ± 10 µA
Elapsed Time Indicator Order Code ET2020/EFA