http://www.sparkfun.com/commerce/product_info.php?products_id=8791

http://www.sparkfun.com/datasheets/Sensors/Accelerometer/SCA3000-Manual.pdf

Just got mine from FedEx today...  Looks pretty straight forward, anyone have fun with it yet?

looks good!, what are you planning?

Trying to suppliment some data I'm gathering with 3 analog gyro's so I can experiment a little with orientation, etc...  =)

Ok..  I'm new to SPI, and new to the mbed..  Can someone guide me in the right direction... ?  My code below, as sad as it is...  doesn't get me much.  I'm not sure I understand the spi command, and the device I'm talking to seems difficult even if I did..  I've tried about a hundred iterations with this, and I am declaring myself stuck... =/  Any nudge in the right direction would be appreciated!

#include "mbed.h"

SPI spi(p5, p6, p7);
DigitalOut led1(LED1);
DigitalOut SCA_RESET_PIN(p23);
DigitalOut SCA_CSB_PIN(p22);
Serial pc(USBTX, USBRX); // tx, rx

int main() {
    int result;
    SCA_RESET_PIN = 0;
    spi.format(16, 0);
//    spi.frequency(1000000);
    pc.baud(921600);
    pc.printf("\033[2J");
    wait(1);
    SCA_RESET_PIN = 1;
    wait(2);
    while(1) {
        SCA_CSB_PIN = 0;
        wait(0.1);
        led1 = 1;
        spi.write(0x05);
        wait(0.1);
        result = spi.write(0x00 | result);
        result = result << 8;
        pc.printf("Accel: %d\r\n",result);
        SCA_CSB_PIN = 1;
        led1 = 0;
        wait(.2);
    }
}

Hi Mark,

Without looking at what you are exactly sending/doing, from the timing diagram I'd suggest the format should perhaps be format(8,0) i.e. you are sending two 8-bit "words" = 16 bits total.

Also, I'd probably consider having CS held at 1 as you come out of reset, else it might not see the first edge.

Simon

Thanks Simon for the response!  I will give those things a try.. 

Ok, I tried format(8,0) amongst a million other things...  Luckily I got my logic analyzer today and have been able to see some mistakes and make some progress as it has an SPI Protocol Analyzer in it..  Fun...

Anyway, from what I can tell with my limited SPI experience is that I am having trouble with LSB/MSB order...  I cannot seem to figure out how to get the mbed to send LSB first...

The datasheet (to expand on the portion I posted above) shows something of what I interpret as a non-"standard" configuration... ??

Here's my code:

#include "mbed.h"

SPI spi(p5, p6, p7);
DigitalOut led1(LED1);
DigitalOut SCA_RESET_PIN(p23);
DigitalOut SCA_CSB_PIN(p22);
Serial pc(USBTX, USBRX); // tx, rx

int main() {
    int result;
    spi.format(16, 0);
//    spi.frequency(1000000);
    pc.baud(921600);
    pc.printf("\033[2J");

    SCA_RESET_PIN = 0;
    wait(0.01);
    SCA_CSB_PIN = 1;
    SCA_RESET_PIN = 1;
    wait(1);
    
    while(1) {
        led1 = 1;
        SCA_CSB_PIN = 0;
        spi.write(0x05);
        result = spi.write(0x04);
        wait(0.000001);
        SCA_CSB_PIN = 1;
        result = result << 8;
        pc.printf("Accel: %d\r\n",result);
        led1 = 0;
    }
}

Here's what I get with my code on the analyzer....

Can someone help!!??!?!?   Please?  =)

One quick note about the above.. I am probably totally wrong about the MSB/LSB order...  And if I switch the analyzer to read MSB first, it displays everything except what I expect the accelerometer wants....  If I look at the first earlier image, the 05h X_MSB is 000101 followed by a 0 and a 0....  I'm not getting that, I get the following.....

Ok, so I figured part of this out.. I shifted the 05h left by 10bits to get it in the right spot, which is what it seems they are doing.....

    int data;
    
    while(1) {
        led1 = 1;
        data = 0x05 << 10;
        SCA_CSB_PIN = 0;
        spi.write(data);
        SCA_CSB_PIN = 1;
wait (0.000001);

        data = 0x04 << 10;
        SCA_CSB_PIN = 0;
        spi.write(data);
        SCA_CSB_PIN = 1;

        result = result << 8;
        pc.printf("Accel: %d\r\n",result);
        led1 = 0;
    }
}

Problem is, it looks exactly like the datasheet now....but my analyzer doesn't agree....

MISO signal definitely doesn't look right. Are you sure you connected the correct pin?

Thanks for the reply Igor...  Right pin on the mbed, yep... Just not connected to the SCA3000 yet...  I was trying to get my ducks in a row before accidentally writing something harmful to the device unintentionally...  =)

I just can't seem to make heads or tails of this thing yet..

Here's what I get when I do the same thing with the SCA3000 connected...  I guess it looks like it's responding... I just haven't a clue if it's what I should expect... hah...

I'm still confused... sadly....

Ok...  As if I haven't posted enough... I do believe I've figured it out.... With one last mystery...  Using the code below, I get three spectacular results as I move the device in three dimensions..  However, somehow...I think I'm not displaying them as they should be..  I don't think I'm doing something right, using int/float/whatever....  Am I on the right track?

#include "mbed.h"

SPI spi(p5, p6, p7);
DigitalOut led1(LED1);
DigitalOut SCA_RESET_PIN(p23);
DigitalOut SCA_CSB_PIN(p22);
Serial pc(USBTX, USBRX); // tx, rx

int main() {
    int result;
    spi.format(16, 1);
//    spi.frequency(1000000);
    pc.baud(921600);

    SCA_RESET_PIN = 0;
    wait(0.01);
    SCA_CSB_PIN = 1;
    SCA_RESET_PIN = 1;
    wait(1);
    
    int data;
    
    while(1) {
        led1 = 1;
        data = 0x05 << 10;
        SCA_CSB_PIN = 0;
        result = spi.write(data);
        SCA_CSB_PIN = 1;
        result = result << 8;
        pc.printf("\033[2J");
        pc.printf("X_MSB: %d\r\n",result);

        data = 0x04 << 10;
        SCA_CSB_PIN = 0;
        result = spi.write(data);
        SCA_CSB_PIN = 1;

        result = result << 8;
        pc.printf("X_LSB: %d\r\n",result);

//

        led1 = 1;
        data = 0x07 << 10;
        SCA_CSB_PIN = 0;
        result = spi.write(data);
        SCA_CSB_PIN = 1;
        result = result << 8;
        pc.printf("Y_MSB: %d\r\n",result);

        data = 0x06 << 10;
        SCA_CSB_PIN = 0;
        result = spi.write(data);
        SCA_CSB_PIN = 1;

        result = result << 8;
        pc.printf("Y_LSB: %d\r\n",result);

//

        led1 = 1;
        data = 0x09 << 10;
        SCA_CSB_PIN = 0;
        result = spi.write(data);
        SCA_CSB_PIN = 1;
        result = result << 8;
        pc.printf("Z_MSB: %d\r\n",result);

        data = 0x08 << 10;
        SCA_CSB_PIN = 0;
        result = spi.write(data);
        SCA_CSB_PIN = 1;

        result = result << 8;
        pc.printf("Z_LSB: %d\r\n",result);

wait(0.05);
        led1 = 0;
    }
}

I'm still lost apparently..  I get a solid MSB that only changes when I tilt the device, not showing anything that makes sense (45' angle would be the same as a 15', move it and the value jumps again..)  At rest it says MSB = 1013 and LSB = 640..  Tilt it and MSB changes to 740, jumps to 1040 and back to 710 and back to 1040, etc...

#include "mbed.h"

SPI spi(p5, p6, p7);
DigitalOut led1(LED1);
DigitalOut SCA_RESET_PIN(p23);
DigitalOut SCA_CSB_PIN(p22);
Serial pc(USBTX, USBRX); // tx, rx

int main() {
    spi.format(16, 0);
//    spi.frequency(1000000);
    pc.baud(921600);

    SCA_RESET_PIN = 0;
    wait(0.01);
    SCA_CSB_PIN = 1;
    SCA_RESET_PIN = 1;
    wait(2);
    
    int X_MSB;
    int X_LSB;
    int BYTE;
    int Address;

    while(1) {
        Address = 0x05;
        BYTE = Address << 10;
        led1 = 1;
        SCA_CSB_PIN = 0;
        X_MSB = spi.write(BYTE);
        SCA_CSB_PIN = 1;
        led1 = 0;
//        X_MSB = X_MSB << 8;
        pc.printf("\033[2J");
        pc.printf("X_MSB: %d\r\n",X_MSB);

        Address = 0x04;
        BYTE = Address << 10;
        led1 = 1;
        SCA_CSB_PIN = 0;
        X_LSB = spi.write(BYTE);
        SCA_CSB_PIN = 1;
        led1 = 0;
//        X_LSB = X_LSB << 8;
        pc.printf("X_LSB: %d\r\n",X_LSB);


wait(0.005);
    }
}

I found these conversations about it.. It doesn't look like anyone has figured it out... ??

http://forum.sparkfun.com/viewtopic.php?t=19998&highlight=sca3000

http://forum.sparkfun.com/viewtopic.php?t=19132&highlight=sca3000

http://forum.sparkfun.com/viewtopic.php?t=18777&highlight=sca3000

http://forum.sparkfun.com/viewtopic.php?t=14366&highlight=sca3000

http://www.vti.fi/midcom-serveattachmentguid-f8d0194a36326993efdc5211fbef229a/tn55_c-code_example_for_sca3000_rev_0.1.pdf

I'm about to give up... =(

Hi Mark,

I don't have one of these, so really can't test, but here is my attempt writing it totally blind from the datasheet:

#include "mbed.h"

SPI spi(p5, p6, p7);
DigitalOut SCA_RESET_PIN(p23);
DigitalOut SCA_CSB_PIN(p22);

DigitalOut led1(LED1);
Serial pc(USBTX, USBRX); // tx, rx

// SCA3000 SPI Format
// [ a(5:0) | nr/w | 0 ] [ d(7:0 ]
int sca3000_read(int address) {
    int nrw = 0;      // we're doing a read
    SCA_CSB_PIN = 0;
    int command = (address << 2) | (nrw << 1); 
    spi.write(command);             // write out the address (1st 8 bits)
    int result = spi.write(0xFF);   // read the result (2nd 8 bits)
    SCA_CSB_PIN = 1;
    return result;
}

int main() {
    pc.baud(921600);
    spi.format(8, 0);
    SCA_RESET_PIN = 0;
    SCA_CSB_PIN = 1;
    wait(0.01);
    SCA_RESET_PIN = 1;
    wait(2);

    // SCA3000 Register Format:
    //  X_MSB @ 0x05   X_LSB @ 0x04
    // [ s | d(11:5) ] [ d(4:0) | x(3) ]
    while (1) {
        int msb = sca3000_read(0x05);
        int lsb = sca3000_read(0x04);
        int16_t result = (msb << 8) | (lsb & 0xF8); // construct result and ignore bottom 3 bits
        pc.printf("X: %d\r\n", result);
        wait(0.005);
    }
}

Not sure it'll actually work, but might give you some hints if you've done anything differently.

Simon

WOW..  Nice job Simon!  I am very impressed!  I tried it and it seems to work with no changes...  I obviously have a bit to learn. 

I really appreciate the help, and I think your example will serve to aid my understanding alot...  Looks like I missed something on putting the msb/lsb together too.. =/

Thanks again!!!!

-mark