122-28029 Parallax Inc, 122-28029 Datasheet - Page 158

• Manufacturer Part Number: 122-28029
• Description: GUIDE STUDENT SMART SENSORS
• Manufacturer: Parallax Inc

Specifications of 122-28029

• Accessory Type: Manual
• Product: Microcontroller Accessories
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• For Use With/related Products: Smart Sensors
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Contains lead / RoHS non-compliant

Page 146 · Smart Sensors and Applications
The procedure for converting a program to average its x and y-axis measurements was
applied to TestCompass.bs2, and then saved as TestCompassAveraged.bs2.
' -----[ Title ]--------------------------------------------------------------
' Smart Sensors and Applications - TestCompassAveraged.bs2
' Test to make sure Hitachi HM55B Compass Module is working.
' {$STAMP BS2}
' {$PBASIC 2.5}
' -----[ I/O Definitions ]----------------------------------------------------
DinDout
Clk
En
' -----[ Constants ]----------------------------------------------------------
Reset
Measure
Report
Ready
NegMask
Negative
Positive
' -----[ Variables ]----------------------------------------------------------
x
y
status
angle
mCount
xSum
ySum
sign
' -----[ Main Routine ]-------------------------------------------------------
√
√
√
√
Open and run TestCompass.bs2 from activity #1.
Watch the x and y-axis measurements at a few different headings. They will
likely be noisy, flickering between two or three different values.
Open and run TestCompassAveraged.bs2.
The measurements should be much more stable. They should only flicker when
you are very close to the transition between two different results.
PIN
PIN
PIN
CON
CON
CON
CON
CON
CON
CON
VAR
VAR
VAR
VAR
VAR
VAR
VAR
VAR
2
0
1
%0000
%1000
%1100
%1100
%1111100000000000
1
0
Word
Word
Nib
Word
Nib
Word
Word
Bit
' P2 transceives to/from Din/Dout
' P0 sends pulses to HM55B's Clk
' P2 controls HM55B's /EN(ABLE)
' Reset command for HM55B
' Start measurement command
' Get status/axis values command
' 11 -> Done, 00 -> no errors
' For 11-bit negative to 16-bits
' Word.bit15 = 1 -> negative
' Word.bit15 = 0 -> positive
' x-axis data
' y-axis data
' Status flags
' Store angle measurement
' Measurement count
' x-axis measurement accumulator
' y-axis measurement accumulator
' Sign bit