Respiratory Pressure. Meter Service Manual. Introduction 3. Operation 3. Respiratory Pressure. Meter Layout 4. Cleaning and Maintaining the

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1 Contents page Introduction Operation Respiratory Pressure Meter Layout SNIP MIP / MEP OFF Cleaning and Maintaining the Respiratory Pressure Meter Disassembling the Respiratory Pressure Meter Reassembling the Respiratory Pressure Meter Circuit Description Parts List Technical Support 0 Circuit Diagram Respiratory Pressure Meter Service Manual 0- Iss..0 October 00

2 Respiratory Pressure Meter Service Manual Information in this document is subject to change without notice and does not represent a commitment on the part of Micro Medical Limited. Only the parts supplied by Micro Medical Limited should be used to complete the service operation described in this manual. If in any way you feel unsure about the successful completion of the service operation you should contact Micro Medical Limited or its appointed agent in your country or region and arrange the despatch of the product to a Micro Medical Limited Service Centre. Copyright 00 by Micro Medical Limited All rights reserved Drawing no. 0- Version.0 October 00 All other products are trademarks or registered trademarks of their respective owners.

3 Introduction The Micro Medical respiratory pressure meter (RPM) is a hand held instrument designed for rapid assessment of inspiratory and expiratory muscle strength. The unit can measure the maximum inspiratory and expiratory mouth pressures, MIP and MEP, and the Sniff Nasal Inspiratory Pressure, SNIP. The result of each measurement is presented in units of cmho gauge pressure on the liquid crystal display screen. The MIP and MEP measurements represents the maximum pressure sustained for second. The SNIP measurement represents the peak pressure detected in the manoeuvre.

4 Respiratory Pressure Meter Layout. Respiratory Pressure Meter PCB. Top Moulding. Bottom Moulding. Mouthpiece Holder. Retaining ring. mm of /" I.D. /" O.D. 'Tygon' tubing. Nylon barb connector. Countersunk screws. Plastic bolt M x mm 0. Cable tie Fig. 0

5 Cleaning and maintaining the Respiratory Pressure Meter The Micro Medical Respiratory Pressure Meter requires no routine maintenance or servicing. Calibration is factory set and should remain constant throughout the lifetime of the device. However the Respiratory Pressure Meter can be calibrated, if in doubt by the Micro Medical Service Centre. Disassembling the Respiratory Pressure Meter. If the Respiratory Pressure Meter becomes faulty then the following procedure is needed to investigate the fault.. Turn the unit face down and slide back the battery cover.. Remove the battery and place to one side.. Remove the screws from the bottom moulding (Item ) and put to one side.. Turn the unit face up and ease the top moulding from the bottom moulding and turn the top moulding to reveal the PCB as shown in Fig. (page ).. Remove the PCB from the bottom moulding and put the bottom moulding to one side.. The Respiratory Pressure Meter is now ready for fault finding. Reassembling the Respiratory Pressure Meter. Place the PCB into the bottom moulding and route the battery lead as shown in Fig... Position the top moulding on top of the bottom moulding and push together (ensure that the battery leads are not trapped).. Turn the unit face down and secure the unit with the retained screws.. Refit the PP battery ensuring correct polarity.. Slide on the battery cover.. The Respiratory Pressure Meter is now ready for operation.

6 Circuit Description Overview A piezo resistive pressure transducer monitors pressure at the mouthpiece holder. After conditioning, the signal from the pressure transducer is applied to a bit analogue to digital converter. A micro controller reads the A/D converter and after applying a calibration factor displays the result on an LCD, which is directly driven from the controller. The measurement displayed is the maximum pressure recorded over a one second interval when the unit is switched to the MIP/MEP position. When the unit is switched to the SNIP position the peak pressure is displayed Power Supply and battery monitoring The Mouth pressure meter is powered by a PP V Alkaline battery with reverse polarity protection, D, and is monitored by channel of the A/D converter through the resistive divider R and R. Battery power is supplied to the circuit via TR. A bi-stable circuit consisting of U, U, R, R, C and R controls TR. The bi-stable circuit can be switched to the off state (pin of U high) by either the front panel switch, SWA, or by the micro controller via TR pulling pin of U low. The unit is switched on when SWA is set to the middle position, pulling on side of R low and applying a momentary pulse to pin of U through the AC coupling action of R and C. The nominal volt supply from the battery is applied to the low drop-out volt regulator, U, which supplies the rest of the circuit. Pressure Sensor Conditioning Circuit The mouth pressure meter consists of an internally temperature compensated solid-state pressure transducer (U). The instrumentation amplifier, U, amplifies the differential signal from the pressure transducer. The gain of U is adjusted by the calibration potentiometer VR that is accessible externally. The reference pin of U and the A/D converter, U, are driven by the output of UB at a voltage derived from the reference output of the A/D converter. The signal from U is passed through a filter consisting of UA, R, R, C and C. This is further filtered by R0 and C0 before being applied to Channel 0 of the A/D converter. Display The display is a / digit custom LCD. A square wave of approximately 0 HZ is continuously applied to each segment and the back plane (BP). To turn a segment off, the square wave applied to it is in phase with the square wave applied to the back plane. To turn a segment on, the square wave applied to it is in anti-phase with the back plane. of the segments and the back plane are driven directly from ports PA, PB and PC of the micro controller, U. The remaining segments are connected to the outputs of a serial to parallel converter, U. The serial peripheral interface of U is used to clock data into U. The clock signal is inverted

7 by TR to obtain the correct polarity. The pull-up resistor for TR is connected to the chip select line of the A/D converter, which is also on the serial peripheral interface, disabling the clock signal when the A/D converter is being accessed by the micro controller. Analogue to Digital converter The A/D converter, U, is a channel, -bit, serial device with internal reference and communicates with the micro controller using the serial peripheral interface. The A/D converter has an input range of COM- VREF/ to COM+VREF/ where VREF is the internal reference voltage of. Volts. The voltage applied to COM, pin, is approximately. volts. This is derived from VREF, pin, using a potential divider, R and R, and a buffer amplifier, UB. The input range for the A/D converter is therefore 0. to. volts. Channel 0, pin, is used to measure the pressure signal. Channel, pin, is connected to the common pin () and to the reference pin of the instrumentation amplifier, U, and is only read during factory set-up. Channel, pin, is connected to the reference output and is only read during factory set-up. Channel, pin, is used to read the battery terminal voltage via the potential divider, R and R. Micro controller The micro controller, U, is an -bit device with integrated RAM, FLASH program memory storage, and power on reset circuitry. The controller communicates with the A/D converter to measure the pressure signal and monitor the battery voltage using its serial peripheral interface bus. This synchronous bus consists of a clock line, pin, a data transmit line, pin, and a data receive line, pin. The controller directly controls of the display segments and the back plane from ports PA, PB and PC. The remaining segments are connected to the outputs of a serial to parallel converter, U. The serial peripheral interface is used to clock data into U. The buzzer is driven from port D, pin, with a square wave at approximately khz. The buzzer is driven in a push-pull arrangement using the inverter U. The controller is factory programmed using the on-board connector CON. The controller is set to program mode by activation of the reed switch, SW. Communication with PC software is achieved through a RS interface. The converter, U0, has on-board circuitry to generate the required +/- 0 Volts and is connected to the serial interface of the controller, pins and 0.

8 Parts List Designation Description. U Motorola OPT Microcontroller U Single surface mount NAND gate U Texas Instruments dual low power OP-Amp U Low drop out surface mount volt regulator U PSI pressure transducer U Analogue devices instrumentation amplifier, U Maxim bit channel surface mount serial D/A U Single surface mount NAND gate U Single surface mount NAND gate U0 Maxim RS transceiver U -bit SIPO shift register TR Rhom NPN surface mount transistor TR Zetex PNP surface mount transistor TR Rhom NPN surface mount transistor D Schottky diode. DISPLAY / digit custom display R K Surface mount resistor 0. watt % size 00 R.K Surface mount resistor 0. watt % size 00 R.K Surface mount resistor 0. watt % size 00 R K Surface mount resistor 0. watt % size 00 R 0K Surface mount resistor 0. watt % size 00 R M Surface mount resistor 0. watt % size 00 R M Surface mount resistor 0. watt % size 00 R 0K Surface mount resistor 0. watt % size 00 R 0K Surface mount resistor 0. watt % size 00 R0 K Surface mount resistor 0. watt % size 00 R 0 ohm Surface mount resistor 0. watt % size 00 R 0K Surface mount resistor 0. watt % size 00 R 00K Surface mount resistor 0. watt % size 00 R K Surface mount resistor 0. watt % size 00 R 0M Surface mount resistor 0. watt % size 00 R 0K Surface mount resistor 0. watt % size 00 R M Surface mount resistor 0. watt % size 00 R 0K Surface mount resistor 0. watt % size 00 R Not used R0 Not used R Not used R Not used R 0K Surface mount resistor 0. watt % size 00 R 0K Surface mount resistor 0. watt % size 00 R K Surface mount resistor 0. watt % size 00 R Not used R 00K Surface mount resistor 0. watt % size 00 R 0K Surface mount resistor 0. watt % size 00 R.K Surface mount resistor 0. watt % size 00 R0 0K Surface mount resistor 0. watt % size 00 VR Bourns k turn potentiometer. C.nF ceramic surface mount capacitor, size 00

9 C pf ceramic surface mount capacitor, size 00 C.nF ceramic surface mount capacitor, size 00 C uf ceramic surface mount capacitor, size 00 C pf ceramic surface mount capacitor, size 00 C uf ceramic surface mount capacitor, size 00 C uf ceramic surface mount capacitor, size 00 C uf ceramic surface mount capacitor, size 00 C uf ceramic surface mount capacitor, size 00 C0 0.uF ceramic surface mount capacitor, size 00 C 0nF ceramic surface mount capacitor, size 00 C nf ceramic surface mount capacitor, size 00 C 0.uF ceramic surface mount capacitor, size 00 C 0.uF ceramic surface mount capacitor, size 00 C 0.uF ceramic surface mount capacitor, size 00 C 0.uF ceramic surface mount capacitor, size 00 C 0.uF ceramic surface mount capacitor, size 00 C 0.uF ceramic surface mount capacitor, size 00 C 0.uF ceramic surface mount capacitor, size 00 C0 0.uF ceramic surface mount capacitor, size 00 C 0.uF ceramic surface mount capacitor, size 00 C uf ceramic surface mount capacitor, size 00 C 0.uF ceramic surface mount capacitor, size 00 C 0.uF ceramic surface mount capacitor, size 00 C pf ceramic surface mount capacitor, size 00 C pf ceramic surface mount capacitor, size 00 C pf ceramic surface mount capacitor, size 00 C 0uF Tantalum capacitor size A. C uf ceramic surface mount capacitor, size 00 C0 uf ceramic surface mount capacitor, size 00 C Not used SW double pole position slide switch SW reed switch. J.mm Stereo jack socket SPK piezo ceramic sounder X. KHz crystal, WATCH package.

10 Technical Support Great Britain and World Headquarters Micro Medical Ltd. PO Box Rochester Kent ME AZ Telephone + (0) 00 Fax + (0) 00 Web Site servicesupport@micromedical.co.uk productsupport@micromedical.co.uk Contact Micro Medical Ltd. for the local agent in your region or country for local service. 0

11 Title Number Revision Size A Date: 0-Oct-00 Sheet of File: G:\Archive\0-0.SCH Drawn By: C pf R 0M V J JACK C pf C uf V RIN TIN V+ V- RO TO C+ C - C+ C - EN FON INV 0 FOFF V U0 MAXCAE C uf C uf C uf V TR DTCEKA R M R M R M C 0.uF BAT PP D ZHCS0 TR FMMT R 0K VIN VOUT U LMM-.0 V R 00K R K SWA SLF00 DIN DOUT SCLK SSTRB SHDN CS VDD CH0 CH CH CH VREF REFADJ DGND AGND 0 COM U MAXBCEE - + UB TLCLCP U BUS U BUS C 0.uF. 0-0 Respiratory Pressure Meter - Circuit diagram A.F. Sadler - + UA TLCLCP V + - U AD R k C n C n R k R k C uf R 0K R K OUT+ OUT- U SDX0D IRQ OSC PD/TCH PD/TCH0 0 OSC PA0/KBD0 PA/KBD PA/KBD PA/KBD PA/KBD PA/KBD PA/KBD PA/KBD PB0/AD0 PB/AD PB/AD PB/AD PB/AD PB/AD PB/AD PB/AD PC0 PC PC PC PC PC PC PD0/SS PD/MIS0 PD/MOS PD/SPSCK PD/TCH0 PD/TCH RST PE0/TxD PE/RxD 0 Vssad/Vrefl VDDa 0 GND V VSSa CGMXFC Vddad/Vrefh 0 U MCHC0GPCFB() R 0K C 0nF C nf V C0 0.uF PTA0 PTA0 SPK SPEAKER R0 K V C 0.uF C 0.uF C 0.uF C 0.uF C0 0.uF C 0.uF C uf V Decoupling Capacito C 0.uF SWB R 0K C 0.uF R 0R V R 0K VR k C pf C pf C pf 0 CON CON0 IRQ PTC0 PTC PTC RESET PTA RESET IRQ PTC0 PTC PTC PTA VDD VDD R 0K R 0K R0 0K R 0K R 0K R 0K SW Reed Switch X CRYSTAL_ R K R 0K PTB0 PTB0 R 0K R 00K U BUS + C 0uF R 0K C uf C0 uf R0 0k C 0.uF BP BAT MEP MIP G F 0 A B G F A B G F A 0 BP 0 SNIP E D C 0 DP E D C DP E D C B DISPLAY DISPLAY_RPM SIN SIN QA QB QC QD GND VCC QH QG QF QE 0 RES CLK U R K TR DTCEK V C

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