AN1315 An Evaluation System Interfacing the MPX2000 Series Pressure Sensors to a Microprocessor

Freescale Semiconductor
Application Note
AN1315
Rev 2, 05/2005
An Evaluation System Interfacing the
MPX2000 Series Pressure Sensors to a
Microprocessor
by: Bill Lucas
Discrete Applications Engineering
INTRODUCTION
PURPOSE
Outputs from compensated and calibrated semiconductor
pressure sensors such as the MPX2000 series devices are
easily amplified and interfaced to a microprocessor. Design
considerations and the description of an evaluation board
using a simple analog interface connected to a
microprocessor is presented here.
The evaluation system shown in Figure 1 shows the ease
of operating and interfacing the Freescale Semiconductor, Inc.
MPX2000 series pressure sensors to a quad operational
amplifier, which amplifies the sensor’s output to an acceptable
level for an analog-to-digital converter. The output of the op
amp is connected to the A/D converter of the microprocessor
and that analog value is then converted to engineering units
and displayed on a liquid crystal display (LCD). This system
may be used to evaluate any of the MPX2000 series pressure
sensors for your specific application.
Figure 1. DEVB158 2000 Series LCD Pressure Gauge EVB
(Board No Longer Available)
© Freescale Semiconductor, Inc., 2005. All rights reserved.
DESCRIPTION
The DEVB158 evaluation system is constructed on a small
printed circuit board. Designed to be powered from a 12 Vdc
power supply, the system will display the pressure applied to
the MPX2000 series sensor in pounds per square inch (PSI)
on the liquid crystal display. Table 1 shows the pressure
sensors that may be used with the system and the pressure
range associated with that particular sensor as well as the
jumper configuration required to support that sensor. These
jumpers are installed at assembly time to correspond with the
supplied sensor. Should the user chose to evaluate a different
sensor other than that supplied with the board, the jumpers
must be changed to correspond to Table 1 for the new sensor.
The displayed pressure is scaled to the full scale (PSI) range
of the installed pressure sensor. No potentiometers are used
in the system to adjust its span and offset. This function is
performed by software.
Table 1. Missing Table Head
Sensor Type
MPX2010
MPX2050
MPX2100
MPX2200
Jumpers
Input Pressure
PSI
J8
J3
0-1.5
0-7.5
0-15.0
0-30
IN
OUT
OUT
OUT
IN
IN
IN
IN
J2
J1
IN
IN
IN OUT
OUT IN
OUT OUT
The signal conditioned sensor's zero pressure offset
voltage with no pressure applied to the sensor is empirically
computed each time power is applied to the system and
stored in RAM. The sensitivity of the MPX2000 series
pressure sensors is quite repeatable from unit to unit. There is
a facility for a small adjustment of the slope constant built into
the program. It is accomplished via jumpers J4 through J7,
and will be explained in the OPERATION section.
Figure 2 shows the printed circuit silkscreen and Figure 3
and Figure 4show the schematic for the system.
The analog section of the system can be broken down into
two subsections. These sections are the power supply and the
amplification section. The power supply section consists of a
diode, used to protect the system from input voltage reversal,
and two fixed voltage regulators. The 5 volt regulator (U3) is
used to power the microprocessor and display. The 8 volt
regulator (U4) is used to power the pressure sensor, voltage
references and a voltage offset source.
The microprocessor section (U5) requires minimal support
hardware to function. The MC34064P-5 (U2) provides an
under voltage sense function and is used to reset the
microprocessor at system power-up. The 4.0 MHz crystal (Y1)
provides the external portion of the oscillator function for
clocking the microprocessor and providing a stable base for
timing functions.
The analog section of the system can be broken down into
two subsections. These sections are the power supply and the
amplification section. The power supply section consists of a
diode, used to protect the system from input voltage reversal,
and two fixed voltage regulators. The 5 volt regulator (U3) is
used to power the microprocessor and display. The 8 volt
regulator (U4) is used to power the pressure sensor, voltage
references and a voltage offset source.
The microprocessor section (U5) requires minimal support
hardware to function. The MC34064P-5 (U2) provides an
under voltage sense function and is used to reset the
microprocessor at system power-up. The 4.0 MHz crystal (Y1)
provides the external portion of the oscillator function for
clocking the microprocessor and providing a stable base for
timing functions.
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Freescale Semiconductor
LCD1
U5
RP1
J1
J2
J3
U2
R4
C8
C2
R15
C7
R1
C3
U3
R5
R8
D1
C1
TP1
Y1
D2
U1
R3
R2
R9
R10
R7
C5
R13
C4
R12
U4
R6
R14
J8
XCDR1
Freescale Discrete Applications Engineering
C6
P1
+12
GND
5.2”
R11
J4
J5
J6
J7
DEVB158
2.9”
Figure 2. Printed Circuit Silkscreen
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3
+12 V
5
J8 Is installed for
the MPX2010 only
– 4 7
6 +U1A
+5.0 V
+5.0 V
6.98K
+8
2
+5.0 V
MC33274
R1
10
–
8
9 +U1C
R5
3
121
R2
200
R3
D2
R4
12
–
14
13 +U1D
340
+8
976
1K
R9
R10
7 x 47K
J1
R8
Sensor Type
Select
U3
78L05
IN
1 µF
+12 IN
P1
GROUND
1N4002
+
IN
U4
78L08
1 µF
GROUND
C1
+5.0 V
C2
0.1
J4
C3
J5
+8
OUT
GROUND
J2
J3
OUT
+
1 µF
+
C5
0.1
3.32K
Slope Adj.
R12
C4
VRH
2–D4
4.53K
J6
R13
VRL
2–D4
402
CPU_Reset
2–B4
+5.0 V
R7
23.7
D1
GND
R6
2K
2
–
1
3 U1B
+ 11
OUT
MC34064P-5
PD0
2–A2
R11
TP1
2K
J8
1
4
XDCR1
1N914
4.7K
4.7K
U2
+IN
R14
J7
PD1
2–A2
PD2
2–A3
PD3
2–A3
PD4
2–A3
PD5
2–A3
PD6
2–A3
PD7
2–A3
Figure 3. Schematic A
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Freescale Semiconductor
Figure 4. Schematic B
AN1315
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Freescale Semiconductor
5
PD7
1–E4
PD5
1–E4
PD1
1–E3
PD1
1–E3
PD6
1–E4
PD4
1–E3
PD2
1–E3
PD0
1–C2
3
4
5
9
11
12
13
14
2
0
18
CPU_RESET
1–E2
RESET
+5 V
43
0.1
15
C6
VPP6
5
44
10
3
46
VDD
4
45
7 34 35 8 31 32 9
7
6
PORTC
42
IRQ
1
48
6
19
PD7
PD6
PD5
PD4
PD3
PD2
PD1
PD0
47
49
28 37 36 5
41
VSS
0
39
10
22
1
38
TCAP1
2
37
33
23
TCAP2
D/A
21
5
34
U5
MC68HC705B5
7
6
PORTB
32
11 29 30 12 26 27 13
LCD1
3
36
50
52
0
31
2
VRL
1C4
7
VRL
29
30
1
24
15 24 25 16 22 23 17
RDI TDO
4
35
14
25
VRH
1C4
8
27
5
20
3
16
22 pF
R15
10M
17
C7
PINS:
2–4, 33, 38–40
OSC1
OSC2
28
1
PLMA
4
26
19 20 21
VRH
7
6
PORTA
18
BLK
PLN
C8
4.00 MHz
Y1
22 pF
Table 2. Parts List
Designators
Quant.
Description
Rating
Manufacturer
Part Number
C3, C4, C6
3
0.1 µF Ceramic Cap.
50 Vdc
Sprague
1C105Z5U104M050B
C1, C2, C5
3
1 µF Ceramic Cap.
50 Vdc
muRATA ERIE
RPE123Z5U105M050V
C7, C8
2
22 pF Ceramic Cap.
100 Vdc
Mepco/Centralab
CN15A220K
J1-J3, J8
J4-J7
3 OR 4
1
#22 or #24 AWG Tined Copper
As Required
Dual Row Straight 4 Pos.
Arranged On 0.1″ Grid
AMP
87227-2
LCD1
1
Liquid Crystal Display
IEE
LCD5657
P1
1
Power Connector
Phoenix Contact
MKDS 1/2-3.81
R1
1
6.98K Ohm resistor 1%
R2
1
121 Ohm Resistor 1%
R3
1
200 Ohm Resistor 1%
R4, R11
2
4.7K Ohm Resistor
R7
1
340 Ohm Resistor 1%
R5, R6
2
2.0K Ohm Resistor 1%
R8
1
23.7 Ohm Resistor 1%
R9
1
976 Ohm Resistor 1%
R10
1
1K Ohm Resistor 1%
R12
1
3.32K Ohm Resistor 1%
CTS
770 Series
R13
1
4.53K Ohm Resistor 1%
R14
1
402 Ohm Resistor 1%
R15
1
10 Meg Ohm Resistor
RP1
1
47K Ohm x 7 SIP Resistor 2%
TP1
1
Test Point
Components Corp.
TP-104-01-02
U1
1
Quad Operational Amplifier
Red
Freescale
MC33274P
U2
1
Under Voltage Detector
Freescale
MC34064P-5
U3
1
5 Volt Fixed Voltage Regulator
Freescale
MC78L05ACP
U4
1
8 Volt Fixed Voltage Regulator
Freescale
MC78L08ACP
U5
1
Microprocessor
Freescale
Freescale
MC68HC705B5FN or
XC68HC705B5FN
XDCR
1
Pressure Sensor
Freescale
MPX2xxxDP
Y1
1
Crystal (Low Profile)
CTS
ATS040SLV
No Designator
1
52 Pin PLCC Socket for U5
AMP
821-575-1
No Designator
4
Jumpers For J4 thru J7
Molex
15-29-1025
No Designator
1
Bare Printed Circuit Board
No Designator
4
Self Sticking Feet
Fastex
5033-01-00-5001
4.0 MHz
Notes: All resistors are 1/4 W resistors with a tolerance of 5% unless otherwise noted.
All capacitors are 100 volt, ceramic capacitors with a tolerance of 10% unless otherwise noted.
AN1315
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OPERATIONAL CHARACTERISTICS
The following operational characteristics are included as a
guide to operation.
Symbol
Min
Max
Unit
Power Supply Voltage
Characteristic
+12
10.75
16
Volts
Operating Current
ICC
75
mA
Full Scale Pressure
MPX2010
MPX2050
MPX2100
MPX2200
Pfs
1.5
7.5
15
30
PSI
PSI
PSI
PSI
the software to allow the user to adjust the slope constant
used for the engineering units calculation (see Table 3). The
pressure and vacuum ports on the sensor must be left open to
atmosphere anytime the board is powered-up. This is
because the zero pressure offset voltage is computed at
power-up.
When you apply power to the system, the LCD will display
CAL for approximately 5 seconds. After that time, pressure or
vacuum may be applied to the sensor. The system will then
start displaying the applied pressure in PSI.
Table 3. Slope Constants
J7
J6
J5
J4
IN
IN
IN
IN
Pin-by-Pin Description
IN
IN
IN
+12
IN
IN
OUT
IN
IN
OUT OUT Decrease the Slope Approximately 5%
Input power is supplied at the +12 terminal. The minimum
operating voltage is 10.75 Vdc and the maximum operating
voltage is 16 Vdc.
GND
Action
Normal Slope
OUT Decrease the Slope Approximately 7%
IN
IN
Decrease the Slope Approximately 6%
IN
OUT
IN
IN
OUT
IN
Decrease the Slope Approximately 4%
IN
OUT OUT
IN
OUT OUT OUT Decrease the Slope Approximately 1%
OUT Decrease the Slope Approximately 3%
IN
Decrease the Slope Approximately 2%
The ground terminal is the power supply return for the
system.
OUT
IN
IN
OUT
IN
IN
TP1
OUT
IN
OUT
Test point 1 is connected to the final op amp stage. It is the
voltage that is applied to the microprocessor's A/D converter.
There are two ports on the pressure sensor located at the
bottom center of the printed circuit board. The pressure port is
on the top left and the vacuum port is on the bottom right of the
sensor.
OUT
IN
OUT OUT Increase the Slope Approximately 4%
OPERATION
Connect the system to a 12 Vdc regulated power supply.
(Note the polarity marked on the power terminal P1.)
Depending on the particular pressure sensor being used with
the system, wire jumpers J1 through J3 and J8 must be
installed at board assembly time. If at some later time it is
desirable to change the type of sensor that is installed on the
board, jumpers J1 through J3 and J8, must be reconfigured for
the system to function properly (see Table 1). If an invalid J1
through J3 jumper combination (i.e., not listed in Table 1) is
used the LCD will display “SE” to indicate that condition.
These jumpers are read by the software and are used to
determine which sensor is installed on the board. Wire jumper
J8 is installed only when an MPX2010DP pressure sensor is
used on the system. The purpose of wire jumper J8 will be
explained later in the text. Jumpers J4 through J7 are read by
OUT OUT
IN
OUT OUT
IN
OUT OUT OUT
IN
Increase the Slope Approximately 1%
OUT Increase the Slope Approximately 2%
IN
IN
Increase the Slope Approximately 3%
Increase the Slope Approximately 5%
OUT Increase the Slope Approximately 6%
IN
Increase the Slope Approximately 7%
OUT OUT OUT OUT Normal Slope
To improve the accuracy of the system, you can change the
constant used by the program that determines the span of the
sensor and amplifier. You will need an accurate test gauge
(using PSI as the reference) to measure the pressure applied
to the sensor. Anytime after the display has completed the
zero calculation, (after CAL is no longer displayed) apply the
sensor's full scale pressure (see Table 1), to the sensor. Make
sure that jumpers J4 through J7 are in the “normal”
configuration (see Table 3). Referring to Table 3, you can
better “calibrate” the system by changing the configuration of
J4 through J7. To “calibrate” the system, compare the display
reading against that of the test gauge (with J4 through J7 in
the “normal slope” configuration). Change the configuration of
J4 through J7 according to Table 3 to obtain the best results.
The calibration jumpers may be changed while the system is
powered up as they are read by the software before each
display update.
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7
DESIGN CONSIDERATIONS
From a hardware point of view, the microprocessor portion
of the system is straight forward. The microprocessor needs
power, a clock source (crystal Y1, two capacitors and a
resistor), and a reset signal to make it function. As for the A/D
converter, external references are required to make it
function. In this case, the power source for the sensor is
divided to produce the voltage references for the A/D
converter. Accurate results will be achieved since the output
from the sensor and the A/D references are ratiometric to its
power supply voltage.
To build a system that will show how to interface an
MPX2000 series pressure sensor to a microprocessor, there
are two main challenges. The first is to take a small differential
signal produced by the sensor and produce a ground
referenced signal of sufficient amplitude to drive a
microprocessor's A/D input. The second challenge is to
understand the microprocessor's operation and to write
software that makes the system function.
+12 V
J8 is installed for
the MPX2010 only
5 – 4
7
6 +U1A
6.98K
+8
2
+5.0 V
R1
MC33274
10 –
8
9 +U1C
3
121
R2
1
4
XDCR1
200
R3
J8
2 –
1
3 +U1B
11
+8
340
R5
2K
R6
1N914
4.7K
D2
PD0
R4
TP1
2K
12 –
14
13 +U1D
976
R10
R9
1K
R7
23.7
R8
Figure 5. Analog Interface
The liquid crystal display is driven by Ports A, B and C of
the microprocessor. There are enough I/O lines on these ports
to provide drive for three full digits, the backplane and two
decimal points. Software routines provide the AC waveform
necessary to drive the display.
The analog portion of the system consists of the pressure
sensor, a quad operational amplifier and the voltage
references for the microprocessor's A/D converter and signal
conditioning circuitry. Figure 5 shows an interface circuit that
will provide a single ended signal with sufficient amplitude to
drive the microprocessor's A/D input. It uses a quad
operational amplifier and several resistors to amplify and level
shift the sensor's output. It is necessary to level shift the output
from the final amplifier into the A/D. Using single power
supplied op amps, the VCE saturation of the output from an op
amp cannot be guaranteed to pull down to zero volts. The
analog design shown here will provide a signal to the A/D
converter with a span of approximately 4 volts when zero to
full-scale pressure is applied to the sensor. The final
amplifier's output is level shifted to approximately 0.7volts.
This will provide a signal that will swing between
approximately 0.7 volts and 4.7 volts. The offset of 0.7 volts in
this implementation does not have to be trimmed to an exact
point. The software will sample the voltage applied to the A/D
converter at initial power up time and call that value “zero”.
The important thing to remember is that the span of the signal
will be approximately 4 volts when zero to full scale pressure
is applied to the sensor. The 4 volt swing in signal may vary
slightly from sensor to sensor and can also vary due to resistor
tolerances in the analog circuitry. Jumpers J4 through J7 may
be placed in various configurations to compensate for these
variations (see Table 3).
Referring to Figure 5, most of the amplification of the
voltage from the pressure sensor is provided by U1A which is
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Freescale Semiconductor
configured as a differential amplifier. U1B serves as a unity
gain buffer in order to keep any current that flows through R2
(and R3) from being fed back into the sensor's negative output.
With zero pressure applied to the sensor, the differential
voltage from pin 2 to pin 4 of the sensor is zero or very close to
zero volts. The common mode, or the voltage measured
between pins 2 or 4 to ground, is equal to approximately one
half of the voltage applied to the sensor, or 4 volts. The zero
pressure output voltage at pin 7 of U1A will then be 4 volts
because pin 1 of U1B is also at 4 volts, creating a zero bias
between pins 5 and 6 of U1A. The four volt zero pressure
output will then be level shifted to the desired zero pressure
offset voltage (approximately 0.7 volts) by U1C and U1D.
Start
Initalize Display I/O Ports
Initalize Timer Registers
Determine Sensor Type
Enable Interrupts
Timer
Interrupt
Service Timer Registers
Setup Counter for Next Interrupt
Service Liquid Crystal Display
Compute Slope Constant
Accumulate 100 A/D Conversions
Compute Input Pressure
Convert to Decimal/Segment Data
Place in Result Output Buffer
Return
Figure 6. DEVB-158 Software Flowchart
To further explain the operation of the level shifting circuitry,
refer again to Figure 5. Assuming zero pressure is applied to
the sensor and the common mode voltage from the sensor is
4 volts, the voltage applied to pin 12 of U1D will be 4 volts,
implying pin 13 will be at 4 volts. The gain of amplifier U1D will
be (R10/(R8+R9)) +1 or a gain of 2. R7 will inject a Voffset
(0.7 volts) into amplifier U1D, thus causing the output at U1D
pin 14 to be 7.3 = (4 volts @ U1D pin 12 × 2) - 0.7 volts. The
gain of U1C is also set at 2 ((R5/R6)+1). With 4 volts applied
to pin 10 of U1C, its output at U1C pin 8 will be 0.7 = ((4 volts
@ U1C pin 10 × 2) - 7.3 volts). For this scheme to work
properly, amplifiers U1C and U1D must have a gain of 2 and
the output of U1D must be shifted down by the Voffset provided
by R7. In this system, the 0.7 volts Voffset was arbitrarily picked
and could have been any voltage greater than the Vsat of the
op amp being used. The system software will take in account
any variations of Voffset as it assumes no pressure is applied
to the sensor at system power up.
The gain of the analog circuit is approximately 117. With the
values shown in Figure 5, the gain of 117 will provide a span
of approximately 4 volts on U1C pin 8 when the pressure
sensor and the 8 volt fixed voltage regulator are at their
maximum output voltage tolerance. All of the sensors listed in
Table 1 with the exception of the MPX2010DP output
approximately 33 mV when full scale pressure is applied.
When the MPX2010DP sensor is used, its full scale sensor
differential output is approximately 20 mV. J8 must be
installed to increase the gain of the analog circuit to still
provide the 4 volts span out of U1C pin 8 with a 20 mV
differential from the sensor.
Diode D2 is used to protect the microprocessor's A/D input
if the output from U1C exceeds 5.6 volts. R4 is used to provide
current limiting into D4 under failure or overvoltage conditions.
SOFTWARE
The source code, compiled listing, and S-record output for
the software used in this system are available on the
Freescale Freeware Bulletin Board Service in the MCU
directory under the filename DEVB158.ARC. To access the
bulletin board, you must have a telephone line, a 300, 1200 or
2400 baud modem and a personal computer. The modem
must be compatible with the Bell 212A standard. Call (512)
891-3733 to access the Bulletin Board Service.
Figure 6 is a flowchart for the program that controls the
system. The software for the system consists of a number of
modules. Their functions provide the capability for system
calibration as well as displaying the pressure input to the
MPX2000 series pressure sensor.
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9
The “C” compiler used in this project was provided by BYTE
CRAFT LTD. (519) 888-6911. A compiler listing of the
program is included at the end of this document. The following
is a brief explanation of the routines:
delay() Used to provide a software loop delay.
read_a2d() Performs 100 reads on the A/D converter on
multiplexer channel 0 and returns the accumulation.
fixcompare() Services the internal timer for 15 ms. timer
compare interrupts.
TIMERCMP() Alternates the data and backplane inputs to
the liquid crystal display.
initio() Sets up the microprocessor's I/O ports, timer and
enables processor interrupts.
adzero() This routine is called at powerup time. It delays to
let the power supply and the transducer stabilize. It then
calls “read_atod()” and saves the returned value as the
sensors output voltage with zero pressure applied.
cvt_bin_dec(unsigned long arg This routine converts the
unsigned binary argument passed in “arg” to a five digit
decimal number in an array called “digit.” It then uses the
decimal results for each digit as an index into a table that
converts the decimal number into a segment pattern for
the display. This is then output to the display.
display_psi() This routine is called from “main()” never to
return. The A/D converter routine is called, the pressure
is calculated based on the type sensor detected and the
pressure applied to the sensor is displayed. The loop then
repeats.
sensor_type() This routine determines the type of sensor
from reading J1 to J3, setting the full scale pressure for
that particular sensor in a variable for use by
display_psi().
sensor_slope() This routine determines the slope constant
to be used by display_psi() for engineering units output.
main() This is the main routine called from reset. It calls
“initio()” to setup the system's I/O. “display_psi()” is called
to compute and display the pressure applied to the
sensor.
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Freescale Semiconductor
6805 'C' COMPILER V3.48
16-Oct-1991
PAGE
1
#pragma option f0;
/*
THE FOLLOWING 'C' SOURCE CODE IS WRITTEN FOR THE DEVB158 EVALUATION
BOARD. IT WAS COMPILED WITH A COMPILER COURTESY OF:
BYTE CRAFT LTD.
421 KING ST.
WATERLOO, ONTARIO
CANADA N2J 4E4
(519)888-6911
SOME SOURCE CODE CHANGES MAY BE NECESSARY FOR COMPILATION WITH OTHER
COMPILERS.
BILL LUCAS 2/5/92
Freescale, SPS
Revision history
rev. 1.0 initial release 3/19/92
rev. 1.1 added additional decimal digit to the MPX2010 sensor. Originally
resolved the output to .1 PSI. Modified cvt_bin_dec to output PSI resolved
to .01 PSI. WLL 9/25/92
0800 1700
0050 0096
*/
#pragma memory ROMPROG [5888]
#pragma memory RAMPAGE0 [150]
1FFE
1FFC
1FFA
1FF8
1FF6
1FF4
1FF2
/*
#pragma
#pragma
#pragma
#pragma
#pragma
#pragma
#pragma
@ 0x0800 ;
@ 0x0050 ;
Vector assignments
*/
vector __RESET
@ 0x1ffe
vector __SWI
@ 0x1ffc
vector IRQ
@ 0x1ffa
vector TIMERCAP @ 0x1ff8
vector TIMERCMP @ 0x1ff6
vector TIMEROV
@ 0x1ff4
vector SCI
@ 0x1ff2
;
;
;
;
;
;
;
#pragma has STOP ;
#pragma has WAIT ;
#pragma has MUL ;
0000
0001
0002
0003
0004
0005
0006
0007
0008
0009
000A
000B
000C
000D
000E
000F
0010
0011
0012
0013
0014
0015
0016
0017
0018
0019
001A
001B
001C
001D
/*
#pragma
#pragma
#pragma
#pragma
#pragma
#pragma
#pragma
#pragma
#pragma
#pragma
#pragma
#pragma
#pragma
#pragma
#pragma
#pragma
#pragma
#pragma
#pragma
#pragma
#pragma
#pragma
#pragma
#pragma
#pragma
#pragma
#pragma
#pragma
#pragma
#pragma
Register assignments for the 68HC705B5 microcontroller
*/
portrw porta
@ 0x00; /*
*/
portrw portb
@ 0x01; /*
*/
portrw portc
@ 0x02; /*
*/
portrw portd
@ 0x03; /* in ,,SS
,SCK ,MOSI ,MISO,TxD,RxD */
portrw ddra
@ 0x04; /* Data direction, Port A
*/
portrw ddrb
@ 0x05; /* Data direction, Port B
*/
portrw ddrc
@ 0x06; /* Data direction, Port C (all output)
*/
portrw eeclk
@ 0x07; /* eeprom/eclk cntl */
portrw addata @ 0x08; /* a/d data register */
portrw adstat @ 0x09; /* a/d stat/control */
portrw plma
@ 0x0a; /* pulse length modulation a */
portrw plmb
@ 0x0b; /* pulse length modulation b */
portrw misc
@ 0x0c; /* miscellaneous register */
portrw scibaud @ 0x0d; /* sci baud rate register */
portrw scicntl1 @ 0x0e; /* sci control 1 */
portrw scicntl2 @ 0x0f; /* sci control 2 */
portrw scistat @ 0x10; /* sci status reg */
portrw scidata
@ 0x11; /* SCI Data */
portrw tcr
@ 0x12; /* ICIE,OCIE,TOIE,0;0,0,IEGE,OLVL
*/
portrw tsr
@ 0x13; /* ICF,OCF,TOF,0; 0,0,0,0
*/
portrw icaphi1
@ 0x14; /* Input Capture Reg (Hi-0x14, Lo-0x15)
*/
portrw icaplo1
@ 0x15; /* Input Capture Reg (Hi-0x14, Lo-0x15)
*/
portrw ocmphi1
@ 0x16; /* Output Compare Reg (Hi-0x16, Lo-0x17) */
portrw ocmplo1
@ 0x17; /* Output Compare Reg (Hi-0x16, Lo-0x17) */
portrw tcnthi
@ 0x18; /* Timer Count Reg (Hi-0x18, Lo-0x19)
*/
portrw tcntlo
@ 0x19; /* Timer Count Reg (Hi-0x18, Lo-0x19)
*/
portrw aregnthi
@ 0x1A; /* Alternate Count Reg (Hi-$1A, Lo-$1B)
*/
portrw aregntlo
@ 0x1B; /* Alternate Count Reg (Hi-$1A, Lo-$1B)
*/
portrw icaphi2
@ 0x1c; /* Input Capture Reg (Hi-0x1c, Lo-0x1d)
*/
portrw icaplo2
@ 0x1d; /* Input Capture Reg (Hi-0x1c, Lo-0x1d)
*/
AN1315
Sensors
Freescale Semiconductor
11
001E
001F
#pragma portrw ocmphi2
#pragma portrw ocmplo2
@ 0x1e;
@ 0x1f;
/* Output Compare Reg (Hi-0x1e, Lo-0x1f)
/* Output Compare Reg (Hi-0x1e, Lo-0x1f)
*/
*/
1EFE 74
#pragma mor @ 0x1efe = 0x74; /* this disables the watchdog counter and does
not add pull-down resistors on ports B and C */
/* put constants and variables here...they must be global */
/***************************************************************************/
0800 FC 30 DA 7A 36 6E E6 38 FE
0809 3E
const char lcdtab[]={0xfc,0x30,0xda,0x7a,0x36,0x6e,0xe6,0x38,0xfe,0x3e };
/* lcd pattern table
0
1
2
3
4
5
6
7
8
9
*/
080A 27 10 03 E8 00 64 00 0A
const long dectable[] = { 10000, 1000, 100, 10 };
0050 0005
unsigned int digit[5]; /* buffer to hold results from cvt_bin_dec function */
0812 00 96 00 4B 00 96 00 1E 00
081B 67
const long type[] = {
150,
75,
150,
30,
103
};
/*
MPX2010 MPX2050 MPX2100 MPX2200 MPX2700
The table above will cause the final results of the pressure to
engineering units to display the 1.5, 7.3 and 15.0 devices with a
decimal place in the tens position. The 30 and 103 psi devices will
display in integer units.
*/
081C
0825
082E
0837
01
B0
01
DD
C2
01
CB
01
01
B4
01
E1
A2
01
CF
01
01 A7 01 AB 01
B9 01 BD 01 C6
01 D4 01 D8 01
C2
const long slope_const[]={ 450,418,423,427,432,436,441,445,454,459,
463,468,472,477,481,450 };
0000
registera areg;
/* processor's A register */
0055
long atodtemp;
/* temp to accumulate 100 a/d readings for smoothing */
0059
long slope;
/* multiplier for adc to engineering units conversion */
005B
int adcnt;
/* a/d converter loop counter */
005C
long xdcr_offset;
/* initial xdcr offset */
005E
0060
long sensor_model; /*
int sensor_index; /*
0061 0063
unsigned long i,j; /* counter for loops */
0065
unsigned int k;
installed sensor based on J1..J3 */
determine the location of the decimal pt. */
/* misc variable */
struct bothbytes
{ int hi;
int lo;
};
union isboth
{ long l;
struct bothbytes b;
};
0066 0002
union isboth q;
/* used for timer set-up */
/***************************************************************************/
0068 0004
006C 0004
0070 0004
/* variables for add32 */
unsigned long SUM[2];
/*
unsigned long ADDEND[2]; /*
unsigned long AUGEND[2]; /*
result
one input
second input
*/
*/
*/
0074 0004
0078 0004
/* variables for sub32 */
unsigned long MINUE[2]; /*
unsigned long SUBTRA[2]; /*
minuend
subtrahend
*/
*/
AN1315
12
Sensors
Freescale Semiconductor
007C 0004
unsigned long DIFF[2];
/*
0080 0004
0084 0004
0088 0004
/* variables for mul32 */
unsigned long MULTP[2]; /*
unsigned long MTEMP[2]; /*
unsigned long MULCAN[2]; /*
multiplier
*/
high order 4 bytes at return */
multiplicand at input, low 4 bytes at return */
008C 0004
0090 0004
0094 0004
0098
/* variables for div32
unsigned long DVDND[2];
unsigned long DVSOR[2];
unsigned long QUO[2];
unsigned int CNT;
Dividend
Divisor
Quotient
Loop counter
*/
/*
/*
/*
/*
difference
*/
*/
*/
*/
*/
/* The code starts here */
/***************************************************************************/
void add32()
{
#asm
083C
083E
0840
0842
0844
0846
0848
084A
084C
084E
0850
0852
0854
B6
BB
B7
B6
B9
B7
B6
B9
B7
B6
B9
B7
81
6F
73
6B
6E
72
6A
6D
71
69
6C
70
68
0855 81
0856
0858
085A
085C
085E
0860
0862
0864
0866
0868
086A
086C
086E
B6
B0
B7
B6
B2
B7
B6
B2
B7
B6
B2
B7
81
RTS
77
7
7F
76
7A
7E
75
79
7D
74
78
7C
*----------------------------------------------------------------------------*
* Add two 32-bit values.
*
Inputs:
*
ADDEND: ADDEND[0..3] HIGH ORDER BYTE IS ADDEND+0
*
AUGEND: AUGEND[0..3] HIGH ORDER BYTE IS AUGEND+0
*
Output:
*
SUM: SUM[0..3] HIGH ORDER BYTE IS SUM+0
*----------------------------------------------------------------------------*
*
LDA ADDEND+3
low byte
ADD AUGEND+3
STA SUM+3
LDA ADDEND+2
medium low byte
ADC AUGEND+2
STA SUM+2
LDA ADDEND+1
medium high byte
ADC AUGEND+1
STA SUM+1
LDA ADDEND
high byte
ADC AUGEND
STA SUM
RTS
done
*
#endasm
}
void sub32()
{
#asm
*----------------------------------------------------------------------------*
* Subtract two 32-bit values.
*
Input:
*
Minuend: MINUE[0..3]
*
Subtrahend: SUBTRA[0..3]
*
Output:
*
Difference: DIFF[1..0]
*----------------------------------------------------------------------------*
*
LDA MINUE+3
low byte
SUB SUBTRA+3
STA DIFF+3
LDA MINUE+2
medium low byte
SBC SUBTRA+2
STA DIFF+2
LDA MINUE+1
medium high byte
SBC SUBTRA+1
STA DIFF+1
LDA MINUE
high byte
SBC SUBTRA
STA DIFF
RTS
done
*
AN1315
Sensors
Freescale Semiconductor
13
086F 81
0870
0872
0874
0876
0878
087A
087C
087E
0880
0882
0884
0886
0888
088A
088C
088E
0890
0892
0894
0896
0898
089A
089C
089E
08A0
08A2
08A4
08A6
08A8
08AA
08AC
08AD
08AF
AE
3F
3F
3F
3F
36
36
36
36
24
B6
BB
B7
B6
B9
B7
B6
B9
B7
B6
B9
B7
36
36
36
36
36
36
36
36
5A
26
81
08B0 81
RTS
#endasm
}
void mul32()
{
#asm
*----------------------------------------------------------------------------*
* Multiply 32-bit value by a 32-bit value
*
*
*
Input:
*
Multiplier:
MULTP[0..3]
*
Multiplicand: MULCAN[0..3]
*
Output:
*
Product:
MTEMP[0..3] AND MULCAN[0..3] MTEMP[0] IS THE HIGH
*
ORDER BYTE AND MULCAN[3] IS THE LOW ORDER BYTE
*
*
THIS ROUTINE DOES NOT USE THE MUL INSTRUCTION FOR THE SAKE OF USERS NOT
*
USING THE HC(7)05 SERIES PROCESSORS.
*----------------------------------------------------------------------------*
*
*
LDX #32
loop counter
CLR MTEMP
clean-up for result
CLR MTEMP+1
*
CLR MTEMP+2
*
CLR MTEMP+3
*
ROR MULCAN
low but to carry, the rest one to the right
ROR MULCAN+1
*
ROR MULCAN+2
*
ROR MULCAN+3
*
MNEXT
BCC ROTATE
if carry is set, do the add
LDA MTEMP+3
*
ADD MULTP+3
*
STA MTEMP+3
*
LDA MTEMP+2
*
ADC MULTP+2
*
STA MTEMP+2
*
LDA MTEMP+1
*
ADC MULTP+1
*
STA MTEMP+1
*
LDA MTEMP
*
ADC MULTP
*
STA MTEMP
*
ROTATE
ROR MTEMP
else: shift low bit to carry, the rest to the right
ROR MTEMP+1
*
ROR MTEMP+2
*
ROR MTEMP+3
*
ROR MULCAN
*
ROR MULCAN+1
*
ROR MULCAN+2
*
ROR MULCAN+3
*
DEX
bump the counter down
BNE MNEXT
done yet ?
RTS
done
20
84
85
86
87
88
89
8A
8B
18
87
83
87
86
82
86
85
81
85
84
80
84
84
85
86
87
88
89
8A
8B
D3
RTS
#endasm
}
void div32()
{
#asm
*
*----------------------------------------------------------------------------*
* Divide 32 bit by 32 bit unsigned integer routine
*
*
Input:
*
Dividend: DVDND [+0..+3] HIGH ORDER BYTE IS DVND+0
*
Divisor:
DVSOR [+0..+3] HIGH ORDER BYTE IS DVSOR+0
*
Output:
*
Quotient: QUO [+0..+3]
HIGH ORDER BYTE IS QUO+0
*----------------------------------------------------------------------------*
*
AN1315
14
Sensors
Freescale Semiconductor
08B1
08B3
08B5
08B7
08B9
08BB
08BD
3F
3F
3F
3F
A6
3D
2B
08BF
08C0
08C2
08C4
08C6
08C8
08CA
08CC
4C
38
39
39
39
2B
A1
26
94
95
96
97
01
90
0F
CLR
CLR
CLR
CLR
LDA
TST
BMI
*
DIV151 INCA
bump the loop counter
ASL DVSOR+3
now shift the divisor until the high order bit = 1
ROL DVSOR+2
ROL DVSOR+1
*
ROL DVSOR
*
BMI DIV153
done if high order bit = 1
CMP #33
have we shifted all possible bits in the DVSOR yet ?
BNE DIV151
no
*
DIV153
STA CNT
save the loop counter so we can do the divide
*
DIV163
LDA DVDND+3
sub 32 bit divisor from dividend
SUB DVSOR+3
*
STA DVDND+3
*
LDA DVDND+2
*
SBC DVSOR+2
*
STA DVDND+2
*
LDA DVDND+1
*
SBC DVSOR+1
*
STA DVDND+1
*
LDA DVDND
*
SBC DVSOR
*
STA DVDND
*
BCC DIV165
carry is clear if DVSOR was larger than DVDND
*
LDA DVDND+3
add the divisor back...was larger than the dividend
ADD DVSOR+3
*
STA DVDND+3
*
LDA DVDND+2
*
ADC DVSOR+2
*
STA DVDND+2
*
LDA DVDND+1
*
ADC DVSOR+1
*
STA DVDND+1
*
LDA DVDND
*
ADC DVSOR
*
STA DVDND
*
CLC
this will clear the respective bit in QUO due to
*
the need to add DVSOR back to DVND
BRA DIV167
DIV165
SEC
this will set the respective bit in QUO
DIV167
ROL QUO+3
set or clear the low order bit in QUO based on above
ROL QUO+2
*
ROL QUO+1
*
ROL QUO
*
LSR DVSOR
divide the divisor by 2
ROR DVSOR+1
*
ROR DVSOR+2
*
ROR DVSOR+3
*
DEC CNT
bump the loop counter down
BNE DIV163
finished yet ?
RTSyes
*
93
92
91
90
04
21
F1
08CE B7 9
08D0
08D2
08D4
08D6
08D8
08DA
08DC
08DE
08E0
08E2
08E4
08E6
08E8
B6
B0
B7
B6
B2
B7
B6
B2
B7
B6
B2
B7
24
8F
93
8F
8E
92
8E
8D
91
8D
8C
90
8C
1B
08EA
08EC
08EE
08F0
08F2
08F4
08F6
08F8
08FA
08FC
08FE
0900
0902
B6
BB
B7
B6
B9
B7
B6
B9
B7
B6
B9
B7
98
8F
93
8F
8E
92
8E
8D
91
8D
8C
90
8C
0903
0905
0906
0908
090A
090C
090E
0910
0912
0914
0916
0918
091A
20
99
39
39
39
39
34
36
36
36
3A
26
81
01
97
96
95
94
90
91
92
93
98
B6
091B 81
QUOzero result registers
QUO+1
*
QUO+2
*
QUO+3
*
#1
initial loop count
DVSOR
if the high order bit is set..no need to shift DVSOR
DIV153
RTS
#endasm
}
/***************************************************************************/
/* These interrupts are not used...give them a graceful return if for
some reason one occurs */
1FFC 09 1C
091C 80
1FFA 09 1D
__SWI(){}
RTI
IRQ(){}
AN1315
Sensors
Freescale Semiconductor
15
091D
1FF8
091E
1FF4
091F
1FF2
0920
80
09 1E
80
09 1F
80
09 20
80
RTI
TIMERCAP(){}
RTI
TIMEROV(){}
RTI
SCI(){}
RTI
/***************************************************************************/
0921
0923
0925
0927
0929
092B
092D
B6
A4
B7
34
B6
A1
23
03
0E
65
65
65
04
0C
LDA
AND
STA
LSR
LDA
CMP
BLS
$03
#$0E
$65
$65
$65
#$04
$093B
092F
0931
0933
0935
0937
0939
3F
A6
B7
A6
B7
20
02
6E
01
CE
00
FE
CLR
LDA
STA
LDA
STA
BRA
$02
#$6E
$01
#$CE
$00
$0939
093B
093D
093F
0940
0941
0944
0946
0949
094B
B6
B7
97
58
D6
B7
D6
B7
81
65
60
LDA
STA
TAX
LSLX
08 12 LDA
5E
STA
08 13 LDA
5F
STA
RTS
$65
$60
void sensor_type()
{
k = portd & 0x0e; /* we only care about bits 1..3 */
k = k >> 1;
if ( k > 4 )
/* right justify the variable */
{ /* we have a set-up error in wire jumpers J1 - J3 */
portc = 0;
/*
*/
portb = 0x6e; /* S */
porta = 0xce;
/* E */
while(1);
}
sensor_index = k;
sensor_model = type[k];
$0812,X
$5E
$0813,X
$5F
}
/***************************************************************************/
094C
094E
0950
0952
0954
0956
0958
095A
095C
095D
0960
0962
0965
0967
B6
A4
B7
34
34
34
34
BE
58
D6
B7
D6
B7
81
03
F0
65
65
65
65
65
65
LDA
AND
STA
LSR
LSR
LSR
LSR
LDX
LSLX
08 1C LDA
59
STA
08 1D LDA
5A
STA
RTS
$03
#$F0
$65
$65
$65
$65
$65
$65
void sensor_slope()
{
k=portd & 0xf0; /* we only care about bits 4..7 */
k = k >> 4;
/* right justify the variable */
slope = slope_const[k];
$081C,X
$59
$081D,X
$5A
}
/***************************************************************************/
0968
096A
096C
096E
0970
0972
0974
0976
0978
097A
097C
097E
3F
3F
B6
A0
B6
A2
24
3C
26
3C
20
81
62
61
62
20
61
4E
08
62
0
61
EE
CLR
CLR
LDA
SUB
LDA
SBC
BCC
INC
BNE
IN
BRA
RTS
$62
$61
$62
#$20
$61
#$4E
$097E
$62
$097C
$61
$096C
void delay(void) /* just hang around for a while */
{
for (i=0; i<20000; ++i);
}
AN1315
16
Sensors
Freescale Semiconductor
/***************************************************************************/
read_a2d(void)
{
/* read the a/d converter on channel 5 and accumulate the result
in atodtemp */
097F
0981
0983
0985
0987
0989
098B
3F
3F
3F
B6
A8
A1
24
56
55
5B
5B
80
E4
21
CLR
CLR
CLR
LDA
EOR
CMP
BCC
$56
$55
$5B
$5B
#$80
#$E4
$09AE
098D
098F
0991
0994
0996
0998
099A
099C
099E
09A0
09A2
09A4
09A6
09A8
A6
B7
0F
B6
3F
B7
BB
B7
B6
B9
B7
B7
B6
B7
20
LDA
#$20
09
STA
$09
09 FD BRCLR 7,$09,$0991
08
LDA
$08
57
CLR
$57
58
STA
$58
56
ADD
$56
58
STA
$58
57
LDA
$57
55
ADC
$55
57
STA
$57
55
STA
$55
58
LDA
$58
56
STA
$56
09AA
09AC
09AE
09B0
09B2
09B4
09B6
09B8
09BA
09BC
09BF
09C2
09C4
09C6
3C
20
B6
B7
B6
B7
3F
A6
B7
CD
CD
BF
B7
81
5B
INC
D7
BRA
56
LDA
58
STA
55
LDA
57
STA
9A
CLR
64
LDA
9B
STA
0B F1 JSR
0C 22 JSR
55
STX
56
STA
RTS
atodtemp=0;
/* zero for accumulation */
for ( adcnt = 0 ; adcnt<100; ++adcnt) /* do 100 a/d conversions */
{
adstat = 0x20;
/* convert on channel 0 */
while (!(adstat & 0x80)); /* wait for a/d to complete */
atodtemp = addata + atodtemp;
}
$5B
$0985
$56
$58
$55
$57
$9A
#$64
$9B
$0BF1
$0C22
$55
$56
atodtemp = atodtemp/100;
return atodtemp;
}
/***************************************************************************/
09C7
09C9
09CB
09CD
09CF
09D1
09D3
09D5
09D7
09D9
09DB
09DD
09DF
09E1
B6
B7
B6
B7
AB
B7
B6
A9
B7
B7
B6
B6
B7
81
18
66
19
67
4C
67
66
1D
66
16
13
67
17
LDA
STA
LDA
STA
ADD
STA
LDA
ADC
STA
STA
LDA
LDA
STA
RTS
$18
$66
$19
$67
#$4C
$67
$66
#$1D
$66
$16
$13
$67
$17
void fixcompare (void)
{
q.b.hi =tcnthi;
/* sets-up the timer compare for the next interrupt */
q.b.lo = tcntlo;
q.l +=7500;
/* ((4mhz xtal/2)/4) = counter period = 2us.*7500 = 15ms. */
ocmphi1 = q.b.hi;
areg=tsr; /* dummy read */
ocmplo1 = q.b.lo;
}
/***************************************************************************/
1FF6
09E2
09E4
09E6
09
33
33
33
E2
02
01
00
COM
COM
COM
$02
$01
$00
void TIMERCMP (void)
{
portc =~ portc;
portb =~ portb;
porta =~ porta;
/* timer service module */
/* service the lcd by inverting the ports */
AN1315
Sensors
Freescale Semiconductor
17
09E8 AD DD
09EA 80
BSR
RTI
$09C7
fixcompare();
}
/***************************************************************************/
void adzero(void)
/* called by initio() to save initial xdcr's zero
pressure offset voltage output */
{
09EB
09ED
09EF
09F1
09F3
09F5
09F7
3F
3F
B6
A0
B6
A2
24
64
63
64
14
63
00
0B
CLR
CLR
LDA
UB
LDA
SBC
BCC
$64
$63
$64
#$14
$63
#$00
$0A04
for ( j=0; j<20; ++j)
/* give the sensor time to "warm-up" and the
power supply time to settle down */
{
09F9 CD 09 68 JSR
$0968
delay();
}
09FC
09FE
0A00
0A02
0A04
0A07
0A09
0A0B
3C
26
3C
20
CD
3F
B7
81
64
INC
02
BNE
63
INC
EB
BRA
09 7F JSR
5C
CLR
5D
STA
RTS
$64
$0A02
$63
$09EF
$097F
$5C
$5D
xdcr_offset =
read_a2d();
}
/***************************************************************************/
0A0C
0A0E
0A10
0A12
0A14
0A16
0A18
0A1A
0A1C
0A1E
0A20
0A22
0A24
0A26
0A28
0A2A
0A2C
A6
B7
3F
3F
3F
A6
B7
B7
B7
B6
3F
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AD
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B7
9A
20
09
02
01
00
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06
05
04
13
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16
1F
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40
12
LDA
STA
CLR
CLR
CLR
LDA
STA
STA
STA
LDA
CLR
CLR
LDA
BSR
LDA
STA
CLI
#$20
$09
$02
$01
$00
#$FF
$06
$05
$04
$13
$1E
$16
$1F
$09C7
#$40
$12
0A2D
0A2F
0A31
0A33
0A35
0A37
0A39
0A3C
0A3E
A6
B7
A6
B7
A6
B7
CD
AD
81
CC
LDA
02
STA
BE
LDA
01
STA
C4
LDA
00
STA
09 21 JSR
AD
BSR
RTS
#$CC
$02
#$BE
$01
#$C4
$00
$0921
$09EB
void initio (void)
/* setup the I/O */
{
adstat = 0x20; /* power-up the A/D */
porta = portb = portc = 0;
ddra = ddrb = ddrc = 0xff;
areg=tsr; /* dummy read */
ocmphi1 = ocmphi2 = 0;
areg = ocmplo2; /* clear out output compare 2 if it happens to be set */
fixcompare(); /* set-up for the first timer interrupt */
tcr = 0x40;
CLI; /* let the interrupts begin !
/* write CAL to the display */
portc = 0xcc; /* C */
*/
portb = 0xbe; /* A */
porta = 0xc4; /* L */
sensor_type(); /* get the model of the sensor based on J1..J3 */
adzero(); /* auto zero */
}
/***************************************************************************/
void cvt_bin_dec(unsigned long arg)
/* First converts the argument to a five digit decimal value. The msd is in
the lowest address. Then leading zero suppress the value and write it to the
display ports.
The argument value is 0..65535 decimal. */
009D
0A3F BF 9D
0A41 B7 9E
{
STX
STA
$9D
$9E
AN1315
18
Sensors
Freescale Semiconductor
009F
00A0
0A43
0A45
0A47
0A49
3F
B6
A1
24
9F
9F
05
07
CLR
LDA
CMP
BCC
$9F
$9F
#$05
$0A52
0A4B 97
0A4C 6F 50
TAX
CL
$50,X
0A4E
0A50
0A52
0A54
0A56
0A58
3C
20
3F
B6
A1
24
9F
F3
9F
9F
04
7A
INC
BRA
CLR
LDA
CMP
BCC
$9F
$0A45
$9F
$9F
#$04
$0AD4
0A5A
0A5B
0A5C
0A5F
0A61
0A63
0A65
0A67
0A69
0A6C
0A6E
97
58
D6
B0
B7
B6
A8
B7
D6
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B2
TAX
LSLX
08 0B LDA
9E
SUB
58
STA
9D
LDA
80
EOR
57
STA
08 0A LDA
80
EOR
57
SBC
char i;
unsigned long l;
for ( i=0; i < 5; ++i )
{
digit[i] = 0x0;
/* put blanks in all digit positions */
}
for ( i=0; i < 4; ++i )
{
if ( arg
>= dectable [i] )
$080B,X
$9E
$58
$9D
#$80
$57
$080A,X
#$80
$57
0A70 BA 58
0A72 22 5C
ORA
BHI
$58
$0AD0
0A74
0A76
0A77
0A7A
0A7C
0A7F
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0A83
0A85
0A87
0A89
0A8B
0A8D
0A8F
0A91
0A94
0A97
0A99
0A9B
0A9D
0A9F
0AA1
0AA3
0AA5
0AA7
0AA9
0AAB
0AAD
0AAF
0AB2
0AB4
0AB6
0AB8
0ABA
0ABC
0ABE
0AC0
0AC2
0AC4
0AC6
0AC8
0ACA
LDX
LSLX
LDA
STA
LDA
STA
LDA
STA
LDA
STA
LDA
STA
LDA
STA
JSR
JSR
STX
STA
LDX
STA
LDX
LDA
CLR
STA
LDA
STA
LDA
STA
JSR
STX
STA
COM
NEG
BNE
INC
LDA
ADD
STA
LDA
ADC
STA
STA
$9F
{
BE
58
D6
B7
D6
B7
B6
B7
B6
B7
B6
B7
B6
B7
CD
CD
BF
B7
BE
E7
BE
E6
3F
B7
B6
B7
B6
B7
CD
BF
B7
33
30
26
3C
B6
BB
B7
B6
B9
B7
B7
9F
08
A0
08
A1
9E
58
9D
57
A0
9A
A1
9B
0B
0C
57
58
9F
50
9F
50
57
58
A0
9A
A1
9B
0B
57
58
57
58
02
57
58
9E
58
57
9D
57
9D
0A
0B
F1
22
D2
$080A,X
$A0
$080B,X
$A1
$9E
$58
$9D
$57
$A0
$9A
$A1
$9B
$0BF1
$0C22
$57
$58
$9F
$50,X
$9F
$50,X
$57
$58
$A0
$9A
$A1
$9B
$0BD2
$57
$58
$57
$58
$0ABE
$57
$58
$9E
$58
$57
$9D
$57
$9D
l = dectable[i];
digit[i] = arg / l;
arg = arg-(digit[i] * l);
AN1315
Sensors
Freescale Semiconductor
19
0ACC B6 58
0ACE B7 9E
LDA
STA
$58
$9E
}
}
0AD0
0AD2
0AD4
0AD6
0AD8
0ADA
0ADC
0ADE
0AE0
3C
20
B6
B7
B6
B7
BE
B6
E7
9F
80
9E
58
9D
57
9F
58
50
INC
BRA
LDA
STA
LDA
STA
LDX
LDA
STA
0AE2
0AE3
0AE5
0AE7
0AE9
0AEB
0AED
0AF0
0AF2
0AF4
0AF6
0AF8
0AFA
0AFC
0AFE
0B00
9B
3D
26
3F
20
BE
D6
B7
3D
26
3D
26
3F
20
BE
D6
52
04
02
07
52
08 00
02
52
08
53
04
01
07
53
08 00
SEI
TST
BNE
CLR
BRA
LDX
LDA
STA
TST
BNE
TST
BNE
CLR
BRA
LDX
LDA
$52
$0AEB
$02
$0AF2
$52
$0800,X
$02
$52
$0AFE
$53
$0AFE
$01
$0B05
$53
$0800,X
0B03
0B05
0B07
0B0A
B7
BE
D6
B7
01
54
08 00
00
STA
LDX
LDA
STA
$01
$54
$0800,X
$00
0B0C
0B0E
0B10
0B12
0B14
0B16
0B19
0B1A
0B1C
0B1E
B6
A8
A1
24
BE
D6
4C
B7
3D
26
60
80
83
08
54
08 00
LDA
EOR
CMP
BCC
LDX
LDA
INCA
STA
TST
BNE
$60
#$80
#$83
$0B1C
$54
$0800,X
0B20
0B22
0B25
0B27
0B29
0B2C
0B2D
BE
D6
B7
BE
D6
4C
B7
54
08 00
00
53
08 00
LDX
LDA
STA
LDX
LDA
INCA
STA
$54
$0800,X
$00
$53
$0800,X
00
60
0F
01
$9F
$0A54
$9E
$58
$9D
$57
$9F
$58
$50,X
digit[i] = arg;
/* now zero suppress and send the lcd pattern to the display */
SEI;
if ( digit[2] == 0 )
/* leading zero suppression */
portc = 0;
else
portc = ( lcdtab[digit[2]] );
/* 100's digit */
if ( digit[2] == 0 && digit[3] == 0 )
portb=0;
else
portb = ( lcdtab[digit[3]] );
porta = ( lcdtab[digit[4]] );
/* 10's digit */
/* 1's digit */
/* place the decimal point only if the sensor is 15 psi or 7.5 psi */
if ( sensor_index < 3 )
porta = ( lcdtab[digit[4]]+1 ); /* add the decimal point to the lsd */
$00
$60
$0B2F
if(sensor_index ==0) /* special case */
{
porta = ( lcdtab[digit[4]] ); /* get rid of the decimal at lsd */
portb = ( lcdtab[digit[3]]+1 ); /* decimal point at middle digit */
$01
}
0B2F 9A
0B30 CD 09 68
0B33 81
CLI
JSR
RTS
CLI;
$0968
delay();
}
/****************************************************************/
void display_psi(void)
/*
At power-up it is assumed that the pressure or vacuum port of
the sensor is open to atmosphere. The code in initio() delays
for the sensor and power supply to stabilize. One hundred A/D
conversions are averaged. That result is called xdcr_offset.
This routine calls the A/D routine which performs one hundred
conversions, divides the result by 100 and returns the value.
If the value returned is less than or equal to the xdcr_offset,
the value of xdcr_offset is substituted. If the value returned
is greater than xdcr_offset, xdcr_offset is subtracted from the
AN1315
20
Sensors
Freescale Semiconductor
returned value.
*/
{
0B34
0B37
0B39
0B3B
0B3D
0B3F
0B41
0B43
0B45
0B47
0B49
0B4B
0B4D
0B4F
0B51
0B53
0B55
0B57
0B59
0B5B
0B5D
0B5F
0B61
0B63
0B66
0B68
0B6A
0B6C
0B6E
CD
3F
B7
B0
B7
B6
A8
B7
B6
A8
B2
BA
22
B6
B7
B6
B7
B6
B0
B7
B6
B2
B7
CD
B6
B7
B6
B7
B6
09 7F
55
56
5D
58
5C
80
57
55
80
57
58
08
5C
55
5D
56
56
5D
56
55
5C
55
09 4C
56
58
55
57
5E
JSR
CLR
STA
SUB
STA
LDA
EOR
STA
LDA
EOR
SBC
ORA
BHI
LDA
STA
LDA
STA
LDA
SUB
STA
LDA
SBC
STA
JSR
LDA
STA
LDA
STA
LDA
$097F
$55
$56
$5D
$58
$5C
#$80
$57
$55
#$80
$57
$58
$0B57
$5C
$55
$5D
$56
$56
$5D
$56
$55
$5C
$55
$094C
$56
$58
$55
$57
$5E
0B70
0B72
0B74
0B76
0B79
0B7B
0B7D
0B7F
0B81
0B83
0B85
0B86
0B88
0B8A
0B8C
0B8E
0B90
0B92
0B94
0B97
0B99
0B9B
0B9D
0B9F
0BA1
0BA3
0BA5
0BA7
0BA9
0BAB
0BAD
0BAF
0BB1
0BB3
0BB5
0BB8
0BBA
0BBC
B7
B6
B7
CD
BF
B7
3F
3F
3F
3F
9F
B7
B6
B7
B6
B7
B6
B7
CD
3F
A6
B7
A6
B7
A6
B7
B6
B7
B6
B7
B6
B7
B6
B7
CD
B6
B7
B6
9A
5F
9B
0B D2
55
56
89
88
81
80
STA
LDA
STA
JSR
STX
STA
CLR
CLR
CLR
CLR
TXA
STA
LDA
STA
LDA
STA
LDA
STA
JSR
CLR
LDA
STA
LDA
STA
LDA
STA
LDA
STA
LDA
STA
LDA
STA
LDA
STA
JSR
LDA
STA
LDA
$9A
$5F
$9B
$0BD2
$55
$56
$89
$88
$81
$80
82
56
83
59
8A
5A
8B
08 70
90
01
91
86
92
A0
93
88
8C
89
8D
8A
8E
8B
8F
08 B1
96
55
97
while(1)
{
atodtemp = read_a2d();
/* atodtemp = raw a/d ( 0..255 ) */
if ( atodtemp <= xdcr_offset )
atodtemp = xdcr_offset;
atodtemp -=
xdcr_offset; /* remove the offset */
sensor_slope(); /* establish the slope constant for this output */
atodtemp *= sensor_model;
MULTP[0] = MULCAN[0] = 0;
MULTP[1] = atodtemp;
$82
$56
$83
$59
$8A
$5A
$8B
$0870
$90
#$01
$91
#$86
$92
#$A0
$93
$88
$8C
$89
$8D
$8A
$8E
$8B
$8F
$08B1
$96
$55
$97
MULCAN[1] = slope;
mul32();
/* analog value * slope based on J1 through J3 */
DVSOR[0] = 1;
/* now divide by 100000 */
DVSOR[1] = 0x86a0;
DVDND[0] = MULCAN[0];
DVDND[1] = MULCAN[1];
div32();
atodtemp = QUO[1]; /* convert to psi */
AN1315
Sensors
Freescale Semiconductor
21
0BBE
0BC0
0BC2
0BC5
0BC8
B7
BE
CD
CC
81
56
55
0A 3F
0B 34
STA
LDX
JSR
JMP
RTS
$56
$55
$0A3F
$0B34
cvt_bin_dec( atodtemp ); /* convert to decimal and display */
}
}
/***************************************************************************/
0BC9
0BCC
0BCF
0BD1
0BD2
0BD4
0BD6
0BD7
0BD9
0BDB
0BDD
0BDF
0BE0
0BE2
0BE4
0BE6
0BE8
0BE9
0BEB
0BED
0BEE
0BF0
0BF1
0BF3
0BF4
0BF6
0BF8
0BF9
CD
CD
20
81
BE
B6
42
B7
BF
BE
B6
42
BB
B7
BE
B6
42
BB
B7
97
B6
81
3F
5F
3F
3F
5C
38
0A 0C
0B 34
FE
0BFB
0BFD
0BFF
0C01
0C03
0C05
0C07
0C09
0C0B
0C0D
0C0F
0C11
0C13
0C15
0C17
0C19
0C1B
0C1C
0C1D
0C1F
0C21
0C22
0C23
0C24
0C26
0C27
1FFE
39
39
39
B6
B0
B7
B6
B2
B7
24
B6
BB
B7
B6
B9
B7
99
59
39
24
81
53
9F
BE
53
81
0B
57
A2
A3
A2
9B
A2
A3
9A
A3
0D
9B
A2
A2
9A
A3
A3
58
9B
A4
A5
57
9B
A5
A5
58
9A
A5
A5
A4
A4
A2
A3
58
A4
D8
A4
JSR
JSR
BRA
RTS
LDX
LDA
MUL
STA
STX
LDX
LDA
MUL
ADD
STA
LDX
LDA
MUL
ADD
STA
TAX
LDA
RTS
CLR
CLRX
CLR
CLR
INCX
LSL
$0A0C
$0B34
$0BCF
ROL
ROL
ROL
LDA
SUB
STA
LDA
SBC
STA
BCC
LDA
ADD
STA
LDA
ADC
STA
SEC
ROLX
ROL
BCC
RTS
COMX
TXA
LDX
COMX
RTS
$57
$A2
$A3
$A2
$9B
$A2
$A3
$9A
$A3
$0C1C
$9B
$A2
$A2
$9A
$A3
$A3
void main()
{
initio(); /* set-up the processor's i/o */
display_psi();
while(1);
/* should never get back to here */
}
$58
$9B
$A4
$A5
$57
$9B
$A5
$A5
$58
$9A
$A5
$A5
$A4
$A4
$A2
$A3
$58
$A4
$0BF9
$A4
C9
SYMBOL TABLE
LABEL
VALUE
LABEL
VALUE
LABEL
VALUE
LABEL
VALUE
AN1315
22
Sensors
Freescale Semiconductor
ADDEND
DIV151
DIV167
MINUE
MULTP
SUBTRA
TIMEROV
__MUL
__STARTUP
__longAC
adstat
arg
cvt_bin_dec
dectable
div32
i
icaplo2
k
main
ocmphi2
plmb
portd
scicntl1
sensor_index
slope
tcntlo
xdcr_offset
006C
08BF
0906
0074
0080
0078
091F
0000
0000
0057
0009
009D
0A3F
080A
08B1
0061
001D
0065
0BC9
001E
000B
0003
000E
0060
0059
0019
005C
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
AUGEND
DIV153
DVDND
MNEXT
QUO
SUM
__LDIV
__MUL16x16
__STOP
adcnt
adzero
atodtemp
ddra
delay
eeclk
icaphi1
initio
l
misc
ocmplo1
porta
q
scicntl2
sensor_model
slope_const
tcr
0070
08CE
008C
0882
0094
0068
0BF1
0BD2
0000
005B
09EB
0055
0004
0968
0007
0014
0A0C
0000
000C
0017
0000
0066
000F
005E
081C
0012
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
CNT
DIV163
DVSOR
MTEMP
ROTATE
TIMERCAP
__LongIX
__RDIV
__SWI
add32
aregnthi
b
ddrb
digit
fixcompare
icaphi2
isboth
lcdtab
mul32
ocmplo2
portb
read_a2d
scidata
sensor_slope
sub32
tsr
0098
08D0
0090
0084
089C
091E
009A
0C22
091C
083C
001A
0000
0005
0050
09C7
001C
0002
0800
0870
001F
0001
097F
0011
094C
0856
0013
|
|
|
|
|
|
|
|
|
|
|
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|
|
|
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DIFF
DIV165
IRQ
MULCAN
SCI
TIMERCMP
__MAIN
__RESET
__WAIT
addata
aregntlo
bothbytes
ddrc
display_psi
hi
icaplo1
j
lo
ocmphi1
plma
portc
scibaud
scistat
sensor_type
tcnthi
type
007C
0905
091D
0088
0920
09E2
0BC9
1FFE
0000
0008
001B
0002
0006
0B34
0000
0015
0063
0001
0016
000A
0002
000D
0010
0921
0018
0812
MEMORY USAGE MAP ('X' = Used, '-' = Unused)
0800
0840
0880
08C0
:
:
:
:
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
0900
0940
0980
09C0
:
:
:
:
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
0A00
0A40
0A80
0AC0
:
:
:
:
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
0B00
0B40
0B80
0BC0
:
:
:
:
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXX
0C00
0C40
0C80
0CC0
:
:
:
:
XXXXXXXXXXXXXXXX
----------------------------------------------
XXXXXXXXXXXXXXXX
----------------------------------------------
XXXXXXXX-----------------------------------------------------
-------------------------------------------------------------
1E00
1E40
1E80
1EC0
:
:
:
:
-------------------------------------------------------------
-------------------------------------------------------------
-------------------------------------------------------------
-----------------------------------------------------------X-
1F00
1F40
1F80
1FC0
:
:
:
:
-------------------------------------------------------------
-------------------------------------------------------------
-------------------------------------------------------------
-----------------------------------------------XXXXXXXXXXXXXX
All other memory blocks unused.
Errors
Warnings
:
:
0
0
AN1315
Sensors
Freescale Semiconductor
23
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AN1315
Rev. 2
05/2005
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