Errors System
A switch with transistors is implemented for the pressure sensor voltage source. The MCU sends a signal to the Q2 base. The
principal voltage source connects to GND and the pressure sensor voltage source is then generated.
Table 8. Power source
Source
+3_3V_D
Device
MC9S08LL16L, MAX4734, LMX9838SB, MC9S08JS16, SD Card, buzzer, QS3VH253Q, push buttons.
(Control or digital section)
+3_3V_M
Motor and valve
+3_3V_PRESS Pressure sensor
Figure 23. Pressure block on/off power
11 Errors System
The system application generates errors in different situations. To prevent any damage in the system and for patient health alerts
an error is generated. The errors are identified with a number and each number of errors alert about different situations.
• Error(1)—Waits a few seconds and if a strip is not detected, the system considers that the strip is used.
• Error(2)—Waits a few seconds and if a strip is detected, but does not have a reaction, the system considers that there is
no blood sample.
• Error(3)—Detects a strip and reaction but there is not enough blood to sample.
• Error(4)—When the pressure detected is higher than 180 mm Hg it is possible that there is an escape of air.
• Error(5)—Heart pulse not detected.
• Error(6)—The diastolic pressure is lower than 30 mm Hg.
• Error(7)—Bluetooth is enabled but cannot make a connection.
• Error(8)—The USB module is enabled but cannot make a connection.
• Error(9)—Connection error with the SD Card.
12 Personal Healthcare Device Class and Medical USB Stack
Applications
Personal Healthcare Devices Class (PHDC)— It is required to implement methods for sending personal healthcare data to a
USB host. The PHDC is to enable seamless interoperability between personal healthcare devices and USB hosts.
Medical USB Stack—Is based on USB PHDC and the IEEE–11073. It is compatible with Continua host emulator software.
This Medical USB Stack enables microcontrollers with guidelines for Continua Health Alliance connectivity and is a first step
to test your application prior official Continua certification.
Freescale provides implementations to the PHDC using the MC9S08JS16.
Implementing a Glucometer and Blood Pressure Monitor Medical Devices, Rev. 1, 4/2010
Freescale Semiconductor, Inc.
25
FREESCALE [ Freescale ]
