DRM101 Datasheet, PDF (35/56 Pages) Freescale Semiconductor, Inc – Blood Pressure Monitor Using the Flexis QE128 Family

Embedded Software Description
To generate the audio, the system uses files stored in the MRAM. These are raw audio files using an 8-bit
sample size with an 8 kHz sampling rate. This sampling rate provides audio with about the same quality
as a telephone. It is important to note that this process can be done at a much higher sampling rate that will
generate full audio. The only change required is for the system to have enough memory to be able to store
the larger audio files.
4.4.7 ZigBee Communication
ZigBee communication on the blood pressure monitor is done through an SPI interface to the MC13202
and six separate I/O ports, including the IRQ pin. The IRQ pin signals when the transceiver has
information that it needs to send to the MCU. The transmission of measured data through ZigBee is done
within the OLED state machine whenever the system is displaying measured data. The state machine will
check to see if ZigBee communication is enabled — if so, it will then place the systolic pressure in the
ZigBee transmission buffer, send that buffer through the SPI to the transceiver, then ask the transceiver to
transmit the buffer. This procedure is then repeated for the diastolic pressure and pulse rate that were taken
at the same time. Due to the fact that all ZigBee communications are initiated by the blood pressure
monitor, whenever the system is not sending messages the transceiver is disabled, as well as all peripherals
related to the transceiver for the MCU.
Blood Pressure Monitor Design Reference Manual, Rev. 0
Freescale Semiconductor
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