MPXY8300 datasheet(78/164 Pages) FREESCALE

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MPXY8300 Series

Sensors

Freescale Semiconductor

SECTION 10 OTHER MCU RESOURCES

The microcontroller used in the MPXY8300 Series has several resources which are used to make sensor measurements and/or

communicate with the RF transmitter within the device. These modules have a range of programmable features, but are not

recommended for user control.

10.1

Analog-to-Digital Converter

The MPXY8300 Series provides a 4-channel, 10-bit analog-to-digital converter (ADC10) module. The ADC10 module is an

analog-to-digital converter using a successive approximation register (SAR) architecture with sample and hold.

When making measurements of the various analog voltages the individual blocks need to be powered up long enough to stabilize

their outputs before a conversion is started.

All of the features of the MPXY8300 Series ADC10 are the same as similar MC9S08 family devices, except that the analog

channels are connected to internal hardware as given in Table 10-1. Conversions are started and ended in the same manner as

are the various power up states.

The accuracy, power consumption and timing specifications given in the electrical specifications in Section 17 are based on using

the assigned firmware subroutines in Section 14 to make these measurements and convert them into an 8-bit or 9-bit transfer

function. These specifications cannot be guaranteed if the user creates custom software routines to make these measurements.

10.2

Serial Peripheral Interface

The serial peripheral interface (SPI) on the MPXY8300 Series is only connected and used internally to communicate between

the MCU and the RFX. The transfer of data back and forth between the two devices is handled by firmware subroutines as

described in Section 14. The user should not attempt to access the RFX using custom software.

10.3

Pressure Measurement

The MPXY8300 Series measures pressure in all members of the family. The pressure measurement consists of a P-Chip

Interface (PCI) to a pressure sensing element as shown in Figure 10-1. Control bits on the MCU operate the PCI using firmware

provided by Freescale as described in Section 14. The PCI transfers trim data to the P-CHip and measures its resulting analog

voltage output. In addition the P-Chip is powered up through the general purpose I/O port.

Figure 10-1 PCI to P-Chip Block Diagram

Table 10-1 ADC10 Channel Select

ADCH

ADC10 Channel

Input Select

Firmware Call(s)

00000

AD0

Pressure Sensor

REIMS_READ_COMP_PRESSURE

00001

AD1

Temperature Sensor

REIMS_READ_COMP_TEMP_8

00010

AD2

Bandgap Reference

REIMS_READ_COMP_VOLTAGE

00011

AD3

Reserved

n/a

00100

AD4

Reserved

n/a

00101

AD5

Acceleration Sensor

REIMS_READ_COMP_ACCEL_X

REIMS_READ_COMP_ACCEL_Z

P-CHIP

INTERFACE

P-CHIP

MCU DATA BUS

VPR

CONTROL

fMFO

MFO

μSec

ADC10

VOUT

AD0

TRIG

MPXY8300 Datasheet(PDF) 78 Page - Freescale Semiconductor, Inc

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