EVEREST PACIFIC TECHNOLOGY CO. LTD
EPT2001-O
DIGITAL COMPASS + ALTIMETER MODULE
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DESCRIPTION The EPT2001-O consists of 2 PNI’s magneto-inductive sensors and its driver to get compass heading data and an INTERSEMA calibrated pressure sensor to get atmospheric pressure. The altitude level referenced to sea level can therefore be approximated accordingly. The weather based on the change in the rate of the pressure over a period can be predicted. A microprocessor controls the measurement sequence of the sensors, and all the parameters that use to compensate for magnetic disturbance are collected during compass calibration.
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FEATURES o Supply voltage 2.5 V to 3.3 V o Low supply current o –10oC ~ +60oC o Digital Compass Range: 0o~359o Accuracy: +/- 5o Resolution: 1o o Pressure Range: 300~1100mbar Accuracy: +/- 1.5mbar Resolution: 1mbar o Altitude Range: -700m~8950m Accuracy +/- 20m Resolution: 1m o Temperature Range: -10oC~+60 oC Accuracy +/- 1 oC Resolution: 0.1 oC o Weather Forecast Sunny Slightly Cloudy Cloudy Rainy o
2005-5-20 rev 4.5
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EVEREST PACIFIC TECHNOLOGY CO. LTD •
BLOCK DIAGRAM V d d = 3 .0 V
M ag neto m eters 2 - A x is
ELI
ELO
M ic r o P ro cesso r
SCLK D IN
P N I1 1 0 9 6 D r iv e r
DOUT SEL G nd
M S5534M
Fig 1. Electrical Block Diagram •
COMPASS MEASUREMENT In operation, the microprocessor takes a pairs of measurements that are combined to calculate the heading data. Raw data is processed at 8Hz to handle gain matching, offset zeroing, phase shifting, and hard iron compensation for the magnetic measurements. To make a measurement, the sensor is switched to into a LR oscillator circuit. The selected sensor oscillates at a frequency, which relates to the magnetic field sensed by the sensor. The “frequency counts” for a certain number of time periods are used to calculate the magnetic field strength measured by each sensor.
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COMPASS CALIBRATION All digital compasses have to be calibrated in order to compensate for magnetic fields other than the earth’s field component to get accurate heading. These additional magnetic fields are generated by the host and therefore depend on the compass mounting location. By performing a simple procedure the module can compensate for steady, static magnetic fields know as hard iron fields. The phase shift due to sensor mounting and axis mismatched can be self-corrected. The backlight offsets (if any) imposed to the field can also be approximated and therefore eliminated. Field components found after a calibration are only valid for a particular orientation and location of the compass. A re-calibration is necessary after a relocation of the compass or if the platform has changed its magnetic character. During calibration procedure the compass collects data required for the compensation algorithm. The goal of the calibration is to sample the magnetic field components for many possible orientations of the host. Rotating the host through 360 degrees or driving in a circle will enable the compass to sample its magnetic environment.
2005-5-20 rev 4.5
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EVEREST PACIFIC TECHNOLOGY CO. LTD •
PRESSURE AND TEMPERATURE MEASUREMENT The MS5534A consists of a piezoresistive sensor and a sensor interface IC. It is to convert the uncompensated analog output voltage into a 16 bit digital value, as well as providing a 16 bit digital value for the temperature. For the pressure measurement, the differential output voltage from the pressure sensor is converted; for the temperature measurement, the sensor bridge resistor is sensed and converted. The 16 bit values for pressure and temperature are read via the serial interface. Then the real pressure and temperature are calculated out of data and calibration coefficients. PRESSURE ALTITUDE CONVERSION Pressure to altitude conversion is based on 1976 US Standard Atmosphere Assumptions. For simplicity, the altitude conversion applies piece-wise linear interpolation with reduced accuracy but with an acceptable number of operations computation time. altitude A(pri) [m] vs pressure [10mbar; kPa]
9000
7000
5000 Pri
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3000
1000
300.00
400.00
500.00
600.00
700.00
800.00
900.00
1000.00
1100.00
-1000 Pi
2005-5-20 rev 4.5
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EVEREST PACIFIC TECHNOLOGY CO. LTD
Altitude error di [m] vs pressure P [kPa=10mbar] 10 8 6 4
di
2 0 300
400
500
600
700
800
900
1000
1100
-2 -4 -6 -8 -10 Pi
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WEATHER FORCAST The weather condition is calculated from absolute pressure once when power up. Absolute Pressure / mbar P < 970 970 < P 1030
Weather Condition Rainy Cloudy Slightly Cloudy Sunny
Weather Code 1 2 3 0
The weather forecast is calculated from the change in pressure per time period. The change in weather condition is directly proportional to the speed of change in barometric pressure. Rising slope indicates High Pressure System and good weather trend. Falling slope means Low Pressure System and bad weather trend. Fluctuating pressure maybe due to sudden change of condition is filtered out and no weather forecast will be made. It will restart to monitor the pressure lotus for preset time period. Barometric pressure keeps constantly rising or falling during past time period, say 1 hour, will effectively change weather condition. (Weather Change is in equal to Pressure Derivative in mbar) It takes barometric pressure every 20mins and compares current pressure with the reference to trace the changing. If the pressure keeps rising or falling more than 1 hour, weather condition will be changed relatively to the change in pressure.
2005-5-20 rev 4.5
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EVEREST PACIFIC TECHNOLOGY CO. LTD •
PIN CONFIGARATION Name VDD ELI * DOUT DIN SEL SCLK GND ELO *
In/Out I I O I I I I O
Pin 1 2 3 4 5 6 7 8
Description Voltage supply 3.0V Back light control in (active high) Data transmit out Data receive in Chip enable & select in Serial data clock out Power and signal ground Back light on/off
* Note: The module can get reliable heading even when the backlight turns on provided that the calibration is performed correctly. Please refer to the programming flow for the procedure.
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SERIAL COMMUNICATION The module communicates with microprocessor via a 4-wire serial interface as shown in Figure 1. The serial clock (SCLK) initiates the data transfer and synchronizes the data transfer with each bit being transmitted on the falling edge of SCLK and each bit being received on the rising edge of SCLK. This signal is generated by master device. The data out (DOUT) indicates the data transmission status and the conversion results. The output data at the data in (DIN) depend on the received command bits. Every communication starts with an instruction sequence at pin DIN. Figure 2 shows the timing diagram. The SEL signal (>50ms) sets the internal logic control into the initial state. It is a must to reset it before the start of the communication. There is a start sequence (3 bits high) and ends with a stop sequence (3 bits low) for each data reading. The start sequence followed by 6 command bits that selects different measurement or calibration. The module acknowledges the completion of conversion by a high to low transition at pin DOUT and data are ready to be read out triggered by data clock (SCLK).
SEL
13th extra clock
>50ms SCLK
// DOUT
//
acknowledge bit7
bit6
bit5
bit4
bit3
bit2
bit1
bit0
bit7
//
bit0
// DIN
bit0 bit1 bit2
bit3
bit4
bit5
bit6
bit7
bit8
bit9 bit10 bit11
Fig 2. Communication Timing Diagram 2005-5-20 rev 4.5
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EVEREST PACIFIC TECHNOLOGY CO. LTD The command bits (Least Significant Bit first) select and start conversion for corresponding mode and return decimal digits in a series way (Most Significant Bit first) as follows: Mode
Command Bits (Bin)
Command Bits (Hex)
Heading Measurement
01 0110B
16H
Calibration (Start/Stop)
11 0010B
32H
Pressure and Weather
10 1010B
2AH
Temperature
10 0110B
26H
Altitude
01 1010B
1AH
Serial Data Format B19 B18 B17 B16
B15 B14 B13 B12
CHKSUM
DATA1000
B11 B10 B9 B8 DATA100
B7 B6
B5 B4
B3 B2 B1 B0
DATA10
DATA1
Check Sum: (4 bits) Æ The hex addition without carry value of the 16 bits data Data: (16 Bits) o Calibration Start/Stop Æ ACK DATA 0A0A if received START/STOP command o Compass Heading Æ 12 Bit heading (0o~359o) and signal disturbed bits (1010B) Case 1: 70135
Heading=135o (magnetic field normal) Checksum=7
Case 2: FA005
Heading=5o (magnetic field disturbed) Checksum=0F
o Pressure and weather Æ 14 Bit pressure (300mbar~1100mbar) and 2 Bit weather code (bit15, bit14) Case 1: 0D003 Pressure=1003mbar; weather code=11 (slightly cloudy) Checksum=3 + 0 + 0 + D=0 Case 2: B0999
Pressure=999mbar; weather code=00 (sunny) Checksum=9 + 9 + 9 + 0=B
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EVEREST PACIFIC TECHNOLOGY CO. LTD o Altitude Æ 16 Bit altitude data (-700m~8950m) in 2’s complement Æ If MSN (most significant nibble) = 9, it is negative. Case 1:52300
MSB=2, Altitude= +2300m
Checksum=5
Case 2:39550
MSB=9, Altitude=10000-9550= -450m Checksum=3
o Temperature Æ 16 Bit temperature data (-10oC~60oC) in 2’s complement
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Case 1: 70250
Temperature=+25.0oC Checksum=7
Case 2: 29900
Temperature= -10.0oC Checksum=0 (1000.0-990.0=10.0)
PROGRAMMING FLOW Start
Idle
=Read Temp?
Read temperature data Calculate temperature
Read pressure and temperature Calculate compensated pressure
=Read Altitude?
Pressure to altitude conversion
Weather forecast decision
(a)
2005-5-20 rev 4.5
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EVEREST PACIFIC TECHNOLOGY CO. LTD •
COMPASS ROUTINE
Start
Idle
Wait command
Measurement
N
=Cal Mode?
Find parameters & Compensate for gain, offset
Y Read raw data Data processing Calculate heading Check signal disturbance
(a)
N
=Start?
Stop calibration
Y
Start calibration
Acknowledge EL Offsets has got? Y
Data Read End?
N Wait data read out
Y
N Wait & Hold EL ON=0.5sec Get EL offsets EL OFF=0.5sec Set ELoffset
Rotate 360o Collect data
End
2005-5-20 rev 4.5
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EVEREST PACIFIC TECHNOLOGY CO. LTD •
OPERATING CONDITIONS
Parameters
Symbol
Min
Type
Max
Unit
Supply Voltage
VDD
2.5
3.0
3.3
V
Supply Current
Istanddby
2
uA
Iconversion Operating Temperature Top Serial Data Clock
- 10
SCLK
64Hz
+ 60
o
100
Hz
C
• APPLICATION NOTE: 1. For Compass Calibration o Put the unit on the level surface and hold it firmly. o Send the START CAL command and wait for the ACK signal. Read out the data. If it returns 0A0Ah, calibration is going. Otherwise, try to send the START CAL command till it’s successfully received. o Backlight turns on for 0.5sec to collect its offset. (If connected) o Turn the unit in two circles slowly. o Send the STOP CAL command to complete. It will return 0A0Ah too as START CAL case to indicate reception is OK. o The module takes about 0.5sec to calculate the coefficients. Should not send any commands to it within this period. 2. Weather Forecast o Send the pressure command (2Ah) every 20mins to perform weather forecast procedure. The module will not do it automatically for less current consumption.
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USEFUL REFERENCES 1. 2.
PNI Magnetic Sensor: INTERSEMA M5534A:
http://www.pnicorp.com/ http://www.intersema.com/
2005-5-20 rev 4.5
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EVEREST PACIFIC TECHNOLOGY CO. LTD
2005-5-20 rev 4.5
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EVEREST PACIFIC TECHNOLOGY CO. LTD
EPT2001-O PAD COORDINATE No 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33
Name BAK XIN XOUT CFIN CFOUT GND VDD1 VDD2 VDD3 VDD4 CUP0 CUP1 CUP2 COM1 COM2 COM3 COM4 COM5 COM6 COM7 COM8 COM9 SEG1(K1) SEG2(K2) SEG3(K3) SEG4(K4) SEG5(K5) SEG6(K6) SEG7(K7) SEG8(K8) SEG9(K9) SEG10(K10) SEG11(K11)
X 72.50 72.50 72.50 72.50 72.50 72.50 72.50 72.50 72.50 72.50 89.50 204.50 319.50 434.50 549.50 669.50 789.50 909.50 1029.50 1149.50 1269.50 1389.50 1509.50 1629.50 1677.50 1677.50 1677.50 1677.50 1677.50 1677.50 1677.50 1677.50 1677.50
Y 1229.50 1114.50 999.50 884.50 769.50 654.50 539.50 424.50 309.50 194.50 72.50 72.50 72.50 72.50 72.50 72.50 72.50 72.50 72.50 72.50 72.50 72.50 72.50 72.50 197.50 322.50 439.50 554.50 669.50 784.50 899.50 1014.50 1129.50
No 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66
2005-5-20 rev 4.5
Name SEG12(K12) SEG13(K13) SEG14(K14) SEG15(K15) SEG16(K16) SEG17 SEG18 SEG19 SEG20 SEG21 SEG22 SEG23 SEG24/IOA1/CX SEG25/IOA2/RR SEG26/IOA3/RT SEG27/IOA4/RH SEG28/IOB1/ELC SEG29/IOB2/ELP SEG30/IOB3/BZB SEG31/IOB4/BZ SEG32/IOC1/KI1 SEG33/IOC2/KI2 SEG34/IOC3/KI3 SEG35/IOC4/KI4 SEG36/IOD1 SEG37/IOD2 SEG38/IOD3 SEG39/IOD4 SEG40 SEG41 RESET INT TEST
X 1677.50 1677.50 1677.50 1677.50 1677.50 1677.50 1677.50 1677.50 1677.50 1677.50 1677.50 1558.50 1430.45 1305.00 1164.50 1024.00 881.50 766.50 651.50 536.50 421.50 306.50 191.50 72.50 72.50 72.50 72.50 72.50 72.50 72.50 72.50 72.50 72.50
Y 1244.50 1359.50 1474.50 1589.50 1704.50 1819.50 1934.50 2049.50 2175.00 2300.00 2477.00 2507.50 2507.50 2507.50 2507.50 2507.50 2507.50 2507.50 2507.50 2507.50 2507.50 2507.50 2507.50 2477.00 2300.00 2175.00 2049.50 1934.50 1819.50 1704.50 1589.50 1474.50 1359.50
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EVEREST PACIFIC TECHNOLOGY CO. LTD EPT2001-O PAD DIAGRAM
2005-5-20 rev 4.5
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EVEREST PACIFIC TECHNOLOGY CO. LTD
PNI11096 PAD DIAGRAM & PIN ASSIGNMENT
Die size is 2580um X 2360um (with scribe line) Pad coordinates All X and Y coordinates refer to the center of the die
PAD 5 - PAD 1
Y (um) PAD 26
(650,968)
(-655,968)
X (um) center of die(0,0)
(-1134,-966) PAD 9 - PAD 17
Remark : substrate flooting
PAD #
PAD NAME
X (um)
PAD 1
VSTBY
-655
968
PAD 2
SCLK
-755
968
PAD 3
MISO
-893
968
PAD 4
MOSI
-1012
968
PAD 5
SSNOT
-1128
968
PAD 6
AVDD
-1125
226
PAD 7
AVSS
-1125
PAD 8
APZDRV
-1125
-81
PAD 9
APZIN
-1134
-966
PAD 10
ANZIN
-1012
-966
PAD 11
ANZDRV
-893
-966
PAD 12
APYDRV
-448
-966
PAD 13
APYIN
-3
-966
PAD 14
DVDD
115
-966
PAD 15
ANYIN
237
-966
PAD 16
ANYDRV
357
-966
PAD 17
APXDRV
802
-966
PAD 18
APXIN
1118
-403
PAD 19
ANXIN
1118
-312
PAD 20
ANXDRV
1118
-189
PAD 21
DVSS
1118
225
PAD 22
COMP
1126
968
PAD 23
RESET
1008
968
PAD 24
DRDY
887
968
PAD 25
DHST
768
968
PAD 26
REXT
650
968
PNI part number index PNI part number 10728 10729 11270
Description 26 pad Die 28 pin SOIC 28 pin MLF
2005-5-20 rev 4.5
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Y (um)
62
