Micro Medical Spiro USB Service Manual

Spiro USB

Service Manual

075-12

Revision 1.0 February 2004

Micro Medical Limited, P.O. Box 6, Rochester, Kent ME1 2AZ

1

Spiro USB - System Overview (Fig. 1)

The Spiro USB is a PC connected spirometer dedicated to work with SPIDA 5
spirometry software.
It consists of a removable digital volume transducer (1) and a housing (2) containing
a microprocessor control circuit and USB driver.
When testing a subject the transducer is inserted into the housing, which is plugged
into a USB socket of a PC. The digital volume transducer is used to measure the
subjects expired flow and volume in accordance with the operating manual.

1

2

2

Transducer (Fig. 2)

The Micro Medical digital volume transducer consists of an acrylic tube with a
vane positioned between two swirl plates. The low inertia vane is attached to a
stainless steel pivot which is free to rotate on two jewelled bearings mounted at the
centre of the swirl plates. As air is passed through the transducer a vortex is created
by the swirl plates which causes the vane to rotate in a direction dependant upon the
direction of air flow. The number of rotations is proportional to the volume of air
passed through the transducer and the frequency of rotation is proportional to the
flow rate. The transducer housing consists of a main body which contains a pair of
light emitting diodes (LED’s) and phototransistors. The transducer is fixed to the
mouthpiece holder which pushes into the main body and is captured by an “O” ring
seal. The LED’s produce infra red beams which are interrupted by the vane twice
per revolution. This interruption is sensed by the phototransistors. The output from
the collector of each phototransistor will be a square wave with a phase difference
between the two of + or - 90 degrees depending upon the direction of flow.
There is no routine maintenance required for the transducer other than cleaning
according to the instructions in the operating manual.

Micro Medical Digital Volume Transducer

Volume proportional to the number of pulses
Flow proportional to the puse frequency

Rotating

vane

Volume = k X No. of pulses

Infra red

emitter

Infra red
detector

Swirl
plate

Flow = k / pulse period

Jewelled

bearing

3

Disassembly (Fig. 3)

1. Carefully remove both Spiro USB labels from the transducer housing.

2. Remove the screw under each label.

3. Pull apart the two halves of the housing as shown below:

Reassembly (Fig. 4)

Please note: Do not use excessive force when reassembling.

1. Ensure the PCB is aligned correctly as shown in Fig. 4.

2. Pull the cable gland through the hole in housing A (already on the cable) and
locate the centre moulding into the housing.

3. Line up the channel on the centre moulding with the screw hole of housing A.

4. When refitting housing B, locate the moulded bracket (with the nut) between
the end of the channel and housing A and carefully pivot housing B around
until the two housings meet (ensuring the blue LED fits into it’s hole).

5. Replace the screws.

6. Carefully reposition the Spiro USB labels.

4

The PCB, LED’S and phototransistors will be accessible as shown below:

Fig. 4.

Centre moulding

Channel

5

Microprocessor control circuit, see drawing 075-01 and 075-02

The microprocessor control circuit monitors the transducer pulses, carries out the
spirometry routines, and communicates with the PC via a USB driver under the
control of it’s internal program.

Power for the processor circuit is derived from the 5 volt USB power line. The power
line is filtered by C12, L1 and C13. The filtered 5 volt is regulated down to 3.3 volts
by the linear regulator, U7. U7 also provides a reset signal for the microprocessor.

The microprocessor, U3, is a Hitachi HD64F2318 16 bit microprocessor with 256K of
flash memory and 8K of Ram. The system clock is supplied by 12MHz crystal, X1.
There is also 512 Kbytes of external RAM, U8, used for storing pulses during a
spirometry manoeuvre. The internal flash memory is used to store the
microprocessor firmware.

Calibration data and system data is stored in an EEPROM, U2. Communication to
the EEPROM is carried out using a two wire serial connection to pins 54 and 55 of
the microprocessor. If the device is ever replaced, the unit will have to undergo
factory recalibration.

Ambient temperature is monitored by a solid-state temperature sensor, U9. It
communicates with the microprocessor via a one wire serial interface on pin 90.
The ambient temperature reading is used for adjusting inspiratory volume at ambient
temperature to volume at body temperature.

The supply to the two series LED’s, mounted inside the transducer housing, is
provided through TR1, which is switched on by pin 4 of the microprocessor during a
spirometry manoeuvre. Inside the transducer housing the two phototransistors used
to detect the interrupted infra-red beam are in open collector configuration. The pull
up resistor for the two phototransistors is provided by R7 and R8.
Pulses from the phototransistor, TR2, are applied to the pulse timing input of the
processor, pin 5, after being squared up by the action of the Schmitt inverter, U4.
Pulses from the second phototransistor, TR3, after conditionings, U5, are applied to
pin 6 of the microprocessor and are used to determine the direction of flow. The
pulse count is used to determine the volume passed through the transducer since
the start of the test and the pulse period is used to determine the flow at each
volume increment.

The microprocessor communicates with the host PC via a USB interface, U6. U6 is
connected to the microprocessor data bus and one address line, A0.

The 512k x 8 static RAM, U8, is located on the underside of the PCB and
communicates with the processor on the 19-bit address bus and 8-bit data bus.

The speaker, J1, is directly connected to ports on pins 91 and 92 that are toggled at
1 KHz to generate the sound.

6

Drawing No. 075-00 Date 07/01/04
Revision No. 1.4 Page: 1 OF 3
Designation Part No. Description.

U1 BU4S11 Individual CMOS Schmitt NAND gate
U2 24LC00-OT 128 bit serial EEPROM
U3 HD64F2318VTE25 Hitachi microcontroller
U4 BU4S584 Individual CMOS Schmitt inverter
U5 BU4S584 Individual CMOS Schmitt inverter
U6 SL811HST USB interface
U7 MAX6349TL 3V3 regulator with integrated RESET
U8 K6X4008T1F-VF70 512k X 8 bit CMOS static RAM,
U9 DS18S20 Digital thermometer
TR1 DTD113EK NPN digital transistor
R1 100K resistor 1%
R2 100K resistor 1%
R3 180 Ohm resistor 1%
R4 10K resistor 1%
R5 10K resistor 1%
R6 1K resistor 1%
R7 4.7K resistor 1%
R8 4.7K resistor 1%
R9 22 Ohm resistor 1%
R10 22 Ohm resistor 1%
R11 1.5K resistor 1%
R12 120 Ohm resistor 1%
R13 100K resistor 1%
C1 33pF ceramic capacitor
C2 33pF ceramic capacitor
C3 100nF ceramic capacitor
C4 100nF ceramic capacitor
C5 100nF ceramic capacitor
C6 100nF ceramic capacitor
C7 1nF ceramic capacitor
C8 1nF ceramic capacitor
C9 100nF ceramic capacitor
C10 100nF ceramic capacitor
C11 4.7uF ceramic capacitor
C12 100nF ceramic capacitor
C13 1uF ceramic capacitor
L1 LQW18ANR22G00D 220nH inductor
X1 12MHz crystal
LED L934MBC Blue LED
LED2 SEP8705 Infra red LED
LED3 SEP8705 Infra red LED
TR2 SDP8405 Infra red photo transistor
TR3 SDP8405 Infra red photo transistor

7

87654321

VCC

5V

U7

1

D

5V

L1

220nH

C12

0.1UF

CON2

1
2
3
4

USB_CON

C

B

A

22R

R9

22R

R10

1 2 3 4 5 6 7 8

C13
1UF

R11

1K5

2

VCC

17

7

D+

8

D-

19

IRQ

44

DRQ-

43

DACK-

40

M/S

5

CM

U6
SL811HST

Ram
RAM.sch

IN

OUT

GND

SET

/MR3/RST

MAX6349SL

RD­WR­RST-

A[0..18]

A[0..18]

D[0..7]

D[0..7]

CS-

CS­RD-

RD-

WR-

WR-

6

5

4

RESET-

X116X2

4

CS-

45
3
18

42

A0

21

D0

D0

27

D1

D1

28

D2

D2

29

D3

D3

31

D4

D4

32

D5

D5

33

D6

D6

39

D7

D7

A[0..18]

D[0..7]

C10

0.1uF

C9

0.1uFC60.1uF

D0
D1
D2
D3
D4
D5
D6
D7

A0
A1
A2
A3
A4
A5
A6
A7

A8
A9
A10
A11
A12
A13
A14
A15

A16
A17
A18

14
15
16
17
19
20
21
22

23
24
25
26
27
28
29
30

32
33
34
35
36
37
38
39

41
42
43
44
45
46
47
48

50
51
52
53

99

100

1
2

69
70
71
72
73
74
75
76

97
96
95
94
93

U3

PE0/D0
PE1/D1
PE2/D2
PE3/D3
PE4/D4
PE5/D5
PE6/D6
PE7/D7

PD0/D8
PD1/D9
PD2/D10
PD3/D11
PD4/D12
PD5/D13
PD6/D14
PD7/D15

PC0/A0
PC1/A1
PC2/A2
PC3/A3
PC4/A4
PC5/A5
PC6/A6
PC7/A7

PB0/A8
PB1/A9
PB2/A10
PB3/A11
PB4/A12
PB5/A13
PB6/A14
PB7/A15

PA0/A16
PA1/A17
PA2/A18
PA3/A19

P10/A20
P11/A21
P12/A22
P13/A23

PF7/CLK
PF6/AS
PF5/RD
PF4/HWR
PF3/LWR/IRQ3
PF2/WAIT/IRQ2
PF1/IRQ1/CS5
PF0/IRQ0/CS4

PG4/CS0
PG3/CS1/CS7
PG2/CS2
PG1/CS3/IRQ7/CS6
PG0/IRQ6

HD64F2318VTE25

C5

0.1uFC40.1uF

VCC

10UF/6V3

+

C11

XTAL

EXTAL

STBY

P30/TXD0
P32/RXD0

P34/SCK0/IRQ4

P31/TXD1
P33/RXD1

P35/SCK1/IRQ5

P14/TIOCA1

P15/TIOCB1/TCLKC

P16/TIOCA2

P17/TIOCB2/TCLKD

P20/TIOCA3

P21/TIOCB3
P22/TIOCC3/TMRI0
P23/TIOCD3/TMCI0
P24/TIOCA4/TMRI1
P25/TIOCB4/TMCI1

P26/TIOCA5/TMO0
P27/TIOCB5/TMO1

P40/AN0
P41/AN1
P42/AN2
P43/AN3
P44/AN4

P45/AN5
P46/AN6/DA0
P47/AN7/DA1

AVCC

VREF

AVSS

FWE

X1

12MHz

TX
RX

TEMP_SEN

1K0

VCC

C1

33pF

VCC

1
2

J1BUZZER

C2

33pF

66
67
62

RESET-

RES

64
63

NMI

57

MD0

58

MD1

61

MODE

MD2

60

FWE

FWE

8
10
12

9
11
13

3
4
5
6

54
55
56
59
89
90
91
92

R6

79
80
81
82
83
84
85
86

77

78

87

4

5V

SCL

SDA

VCC

VCC

R3
1K

LED
LED

VCC VCC

R5
10KR410K

R1
100K

53

U1

1

2

BU4S11

R2
100K

TIMER_A

DIR

1

2

TX
RX

MODE

4

4

U2

SCL

VSS

SDA3NC

24LC00-OT

VCC

CON1

1
2
3
4
5

PROGRAMMING PORT

R13
100K

TEMP_SEN

Temperature Sensor

VCC

VCC

53

U4

1

2

BU4S584

VCC

53

U5

1

2

BU4S584

5

VCC

4

Title

A3

Date: 12-Feb-2004 Sheet of
File: G:\Archive\Temp\075-01.sch Drawn By:

VCC

C3
100nF

USB SPIROMETER

Number RevisionSize

R7
4K7

C7

1nF

VCC

R8
4K7

C8
1nF

075-01 1.2

VCCVCC

U9

1

VDD

2

DQ

3

GND

DS18S20

5V

R12
120R

12

TR2

LED3

TDET500C

TEMT1288C

D

C

Note:
LED2, LED3, TR2 and TR3
are external components.

12

1

TR3
TDET500C

LED2
TEMT1288C

32

TR1
DTD113EK

Arthur Sadler

B

A

8

87654321

D

12

A0

11

A1

10

A2

9

A3

8

A4

7

A5

6

A6

5

A7

27

A8

26

A9

23

A10

25

A11

4

A12

28

A13

3

A14

31

A15

2

A16

30

A17

1

A18

24

OE

29

WE

22

CS1

U8
K6X4008T1F-VB70

VCC

32

13

D0

D0

14

D1

D1

VCC

15

D2

D2

17

D3

D3

18

D4

D4

19

D5

D5

20

D6

D6

21

D7

D7

512K x 8

A[0..18] D[0..7]

C

RD­WR­CS-

B

A0
A1
A2
A3
A4
A5
A6
A7
A8
A9
A10
A11
A12
A13
A14
A15
A16
A17
A18

D[0..7]A[0..18]

D

C

B

A

Title

Spiro USB - Circuit diagram, memory

Number RevisionSize

A3

Date: 12-Feb-2004 Sheet of

1 2 3 4 5 6 7 8

File: G:\Archive\Temp\075-02.sch Drawn By:

075-02 1.0

Arthur Sadler

A

9