' h48c_3-axis_wpd_enabled.bs2
'
' THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY OF
' ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO
' THE IMPLIED WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A
' PARTICULAR PURPOSE.
'
' Copyright (c) Microsoft Corporation. All rights reserved
'
' {$STAMP BS2}
' {$PBASIC 2.5}
'
' =========================================================================

' -----[ Program Description ]---------------------------------------------
'
' Test program for the H48C 3-Axis Accelerometer module.
'
' Connections:
'
'       +------------+
'       |  *         |
'   CLK | o        o | Vdd (+5v)
'       |    +--+    |
'   DIO [ o  |  |  o | CS\
'       |    +--+    |
'   Vss | o        o | 0G (free-fall indication)
'       |            |
'       +------------+
'
' How it Works:
'
' An onboard MCP3204 12-bit ADC is used to read the VRef, X-, Y-, and
' Z-axis outputs from the Hitachi H48C accelerometer.  The reference
' voltage output from H48C is 1.65 volts (3.3 / 2).
'
' After reading the reference voltage and an output channel the g-force
' for the channel is calculated with this formula:
'
'        axis - vref    3.3
'    G = ----------- x ------
'            4095      0.3663
'
' For use in the program the forumla can be simplified to:
'
'    G = (axis - vref) x 0.0022
'
' To allow the display of fractional g-force in the integer system of the
' BASIC Stamp we multiply 0.0022 by 100 -- this will allow us to display
' g-force in 0.01g units.



' -----[ I/O Definitions ]-------------------------------------------------

Dio             PIN     15                      ' data to/from module
Clk             PIN     14                      ' clock output
CS              PIN     13                      ' active-low chip select


' -----[ Constants ]-------------------------------------------------------

XAxis           CON     0                       ' adc channels
YAxis           CON     1
ZAxis           CON     2
VRef            CON     3

Cnt2Mv          CON     $CE4C                   ' counts to millivolts
                                                '   0.80586 with **
GfCnv           CON     $3852                   ' g-force conversion
                                                '   0.22 with **

' -----[ Variables ]-------------------------------------------------------

axis            VAR     Nib                     ' axis selection
rvCount         VAR     Word                    ' ref voltage adc counts
axCount         VAR     Word                    ' axis voltage adc counts
mVolts          VAR     Word                    ' millivolts
Gforce          VAR     Word                    ' axis g-force

xGforce        VAR     Word                      ' x-axis force
yGforce        VAR     Word                      ' y-axis force
zGforce        VAR     Word                      ' z-axis force

dValue          VAR     Word                    ' display value
dPad            VAR     Nib                     ' display pad

' Below lines are WPD additions

SensorID  VAR   Byte  'Sensor identifier = 9 for Hitachi
ElementCount  VAR   Byte  'Count of elements in packet
ElementSize VAR Byte  'Size (in bytes) of each element


NewInterval VAR  Word  'New interval requested by user
Interval  VAR   Word  'Interval value utlized by firmware

SensorID = 9
ElementSize = 4       'Each element contains a sign byte, followed by a G-force integer value, followed by a G-force fraction (in hundredths).
ElementCount = 3      'Each element corresponds to one of the three axis (X, Y, and Z)

Interval = 2000
NewInterval = 2000


' -----[ EEPROM Data ]-----------------------------------------------------


' -----[ Initialization ]--------------------------------------------------

Reset:
  HIGH CS                                       ' deselect module

' -----[ Program Code ]----------------------------------------------------

Main:
  GOSUB GetGforces        'Retrieves G-forces along 3 axis
  GOSUB RetrieveInterval  'Retrieves event-interval data

  Timeout:
    SEROUT 16, 16780, [DEC1 SensorID, DEC1 ElementSize, DEC1 ElementCount, DEC1(xGforce.BIT15), DEC1(ABS xGforce/100),DEC2(ABS xGforce),DEC1(yGforce.BIT15),DEC1(ABS yGforce/100),DEC2(ABS yGforce),DEC1(zGforce.BIT15),DEC1(ABS zGforce/100),DEC2(ABS zGforce),DEC5 Interval ]
    GOTO Main

  GOTO Main


' -----[ Subroutines ]-----------------------------------------------------

' Retrieves the event-interval property from the WPD driver
RetrieveInterval:
 SERIN 16, 16780, Interval, Timeout, [DEC NewInterval]   'Retrieve interval
 IF NewInterval >= 10 AND NewInterval <= 60000 THEN
   Interval = NewInterval
 ENDIF

' Retrieves G forces along all three axis
GetGforces:
  FOR axis = XAxis TO ZAxis                     ' loop through each axis
    GOSUB Get_H48C                              ' read vRef & axis counts
    ' calculate g-force
    ' -- "Gforce" is signed word
    IF (axCount >= rvCount) THEN
      Gforce = (axCount - rvCount) ** GfCnv     ' positive g-force
    ELSE
      Gforce = -((rvCount - axCount) ** GfCnv)  ' negative g-force
    ENDIF
    IF (axis = XAxis) THEN
          xGforce = Gforce
    ENDIF
    IF (axis = YAxis) THEN
          yGforce = Gforce
    ENDIF
    IF (axis = ZAxis) THEN
          zGforce = Gforce
     ENDIF
  NEXT
  RETURN

' Reads VRef and selected H48C axis through an MCP3204 ADC
' -- pass axis (0 - 2) in "axis"
' -- returns reference voltage counts in "rvCount"
' -- returns axis voltage counts in "axCounts"

Get_H48C:
  LOW CS
  SHIFTOUT Dio, Clk, MSBFIRST, [%11\2, VRef\3]  ' select vref register
  SHIFTIN  Dio, Clk, MSBPOST, [rvCount\13]      ' read ref voltage counts
  HIGH CS
  PAUSE 1
  LOW CS
  SHIFTOUT Dio, Clk, MSBFIRST, [%11\2, axis\3]  ' select axis
  SHIFTIN  Dio, Clk, MSBPOST, [axCount\13]      ' read axis voltage counts
  HIGH CS
  RETURN