3-Axis Accelerometer (LIS302DL)

[Gusse]

I noticed couple of misstakes in the code.

One in the two's complement calculation formula. Previously posted formula gave result as: 255 = 0, 254 = (-)1, etc ... Correct formula should give 255 = (-)1, 254 = (-)2, etc ...
Error was minor, but here is updated code (only change is 255 -> 256).

Other in Acceleration_Menu -loop. Accelerometer_Init required only once you start.

Acceleratio     var word
Acceleratio_max var word
X_Data          var Byte
Y_Data          var Byte
COUNTER         VAR BYTE
TEMP            VAR BYTE

'-------------------------------------------------------------------------------
Accelerometer_Init:
    Acceleratio = 0      
    Acceleratio_max = 0
    COUNTER = 0         
    
'Axes
I2CAddress_3D = $20     'CTRL_REG1
TEMP = %01000011        'DR=0, PD=1, FS=0, STP=00, Zen=0, Yen=1, Xen=1 (X,Y enable, Output 100Hz)
gosub I2C_Write_3D      '

'Interrupts
I2CAddress_3D = $22     'CTRL_REG3
TEMP = %00000100        'IHL = 0, PP_OD = 0, I2CFG2-0 = 000, I1CFG2-0 = 100 (DataReady = INT1)
gosub I2C_Write_3D

Return

'-------------------------------------------------------------------------------
I2C_Write_3D:
I2CWRITE SDA_3D, SCL_3D, I2CDevice_3D_write, I2CAddress_3D,[ TEMP ]
Return

I2C_Read_3D:
I2cread SDA_3D, SCL_3D, I2CDevice_3D_read, I2CAddress_3D,[ TEMP ]
Return

'-------------------------------------------------------------------------------
Acceleration_Menu:
    gosub Accelerometer_Init                'Start from here

Acceleration_Loop:                                 
    IF Int1_3D = 1 THEN                     'Int1_3D is IO pin for Interrup coming from 3D sensor, DataReady in device     
        COUNTER = COUNTER + 1
        '---------------------------
            I2CAddress_3D = $29             'Read OUTX value
            gosub I2C_Read_3D
            if TEMP > 127 then              'Two's complementary changed to amplitude information
                    X_Data = 256 - TEMP     'Acceleration data presented in two's complement
                else      
                    X_Data = TEMP
            ENDIF
        '---------------------------
            I2CAddress_3D = $2B             'Read OUTY value 
            gosub I2C_Read_3D
            if TEMP > 127 then              'Two's complementary changed to amplitude information
                    Y_Data = 256 - TEMP     'Acceleration data presented in two's complement
                else      
                    Y_Data = TEMP
            ENDIF
        '---------------------------
        Acceleratio = Acceleratio + (18 * SQR((X_Data * X_Data) + (Y_Data * Y_Data)))   'Average factor 5x
        '---------------------------                                                    'Calculate resultant force
            IF COUNTER = 5 then
                COUNTER = 0
                Acceleratio = Acceleratio/5    
                IF Acceleratio > Acceleratio_max then
                    Acceleratio_max = Acceleratio
                endif
                'ADD YOUR CODE HERE TO SHOW ACCELERATIO AND ACCELERATIO_MAX ON YOUR DISPLAY
                Acceleratio = 0
            endif
        '---------------------------
        Gosub Accelerometer_Clear
    endif
    goto Acceleration_Loop
'-------------------------------------------------------------------------------
Accelerometer_Clear:            'Clear interrupt
    I2CAddress_3D = $31
    gosub I2C_Read_3D
    Return

Looks really good, if I knowed this before I started myself I probably would have ordered a I2C version instead

..But I might borrow some of your code anyway

I was thinking of using a timer and calculate speed from it, but I dont know how accurate it would be.

Thanks! Feel free to borrow, therefore I posted it here
I would guess that digi output device would give overall better accuracy, but I might be wrong.

BR,
-Gusse-

[Gusse]

It seems to work quite nicely.

1) Start value ~0.07 - 0.10G. X-axis = 0 deg, Y-axis = 0 deg.

2) Y-axis tilted 90 deg. Should show 1G in this position. OK.

3) X-axis tilted ~45 deg.

BR,
-Gusse-

[Glenn]

Nice!

And a LCD that looks identical as the one that I have cannibalized out of a nokia phone and going to solder wires on to use with my PIC's

Do you want to post the updated code too ?

..This is how far I got..

http://www.repulsiv.se/pics/accelero...breadboard.jpg

Your setup is much more elegant

..Note that I already connected a cable for an Z-axis, I bought a prototypeboard with a 3-axis accelerometer from sure electronics that I'm going to use too.

The "normal" value seem to be 120, and using 8bit AD-converter that would be.. lets se..

5v Vref /256 = 0,01953125
120 * 0,01953125 = 2,34375

With a Vref at 5v 1G should be 2.5V, so its a bit strange..

I have to make some effort at making PBP do that math and display the "real" G-value too.. readed Melanies thread about it but.. well

[Gusse]

Display is from Nokia 3310 and it is easy to play with. Yeah!

I could try to make a code with all neccesary LCD srcipts too. At the moment this accelerometer is just one part of a bigger system and a part of a bigger code bunch. It will take some time, but I'll come back with the code, no problem. Anyway, origin of the display driver is from this forum, therefore I would like to thank those who have done the pioneer work! Thanks!

As said earlier, my primary use case was motion detection (alarm). For that purpose LIS302DL works fine, but then I started to look more advanced solutions; acceleration, speed, range, etc. Nice features, but one problem is causing grey hairs to my.

If device is at fully horisontal level (Z-axis is pointing to center of the earth), then everything is OK. But if it is rotated/tilted X, Y, Z or any combinations (pitch, roll, yaw), then readings are not any more right. Spec also says so.

There are quite lot of discussions about how to get rid of this limitation, but no really simply solution. This is one good post, which describes more accurately the problem http://www.electronicspoint.com/acce...n-t119225.html

BR,
-Gusse-

EDIT: Here is also code for LIS302DL with Nokia 3310 LCD. This one shows captured acceleration values on screen: 1st X, 2nd Y, 3rd Z. No bargraphics included because grachics are located in external EEPROM. LCD is connected to PortB, accelerometer to PortC & D (partial), see file for more details. Change pins to fit you application (I'm using 16F877A).

[Gusse]

Here is an updated demo code for LIS302DL with Nokia 3310 LCD. This shows all three axis with bar graphics and numbers.

Also small video clip, which shows how the system works (I'm rotation PIC and LIS302DL in my hand) http://kotiweb.kotiportti.fi/karl-er...C/LIS302DL.wmv.

My test bench for accelerometer (add-on board) http://kotiweb.kotiportti.fi/karl-er...d_LIS302DL.gif.

And here is the code.

BR,
-Gusse-

EDIT: If your screen is too light or too dark then tune "Contrast" value. I have noticed that there are differences between new and old 3310 LCD displays (tested both).

[alexpanrui]

my lis302dl is not working properly.....no matter which register i tried to read, the data is always 0xFF....shouldnt be right according to the datasheet....even the Who_AM_I register gave me 0xFF...BTW the sensor was working few days a ago. is it detected?help.....

[alexpanrui]

I am using PIC16f877 to interface with LIS302DL. I browsed through some threads available over the net. They said we need to add pullups at the data lines and SCL. why? I dont include any pullups. i just directly connect the sensor to the PIC. anything wrong?