Revision 0:c6ee363ac724, committed 2011-08-10

Comitter:

yahugh

Date:

Wed Aug 10 21:50:36 2011 +0000

Commit message:

initial release, still has some problems but might be of interest to others regardless

Changed in this revision

diff -r 000000000000 -r c6ee363ac724 imu-spi.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/imu-spi.cpp	Wed Aug 10 21:50:36 2011 +0000
@@ -0,0 +1,98 @@
+//
+// imu-spi.cpp
+//
+// copyright 2010 Hugh Shane
+//
+#include "mbed.h"
+#include "imu-spi.h"
+
+ImuSpi::ImuSpi(void) :
+    spi(p5, p6, p7), // mosi, miso, sclk
+    cs(p8), // IMU chip select
+    reset(p8), // IMU reset. CAUTION! This also resets the altimeter.
+    diag(p21), // diagnostic output
+    imuDataReady(p11) // interrupt on IMU data-ready
+{
+    // Setup the spi for 16 bit data, high steady state clock,
+    // second edge capture, with a 1 MHz clock rate
+    spi.format(16,3);
+    spi.frequency(1000000);
+    
+    // init the pingpong buffer
+    pingpong = 0;
+    
+    // init the interrupt semaphore
+    dataReady = false;    
+    
+    // interrupt on the falling edge of the IMU data-ready signal
+    diag = 0;
+    imuDataReady.fall(this, &ImuSpi::DataReadyISR);
+    
+    // init the IMU
+    InitImu();
+
+}
+
+void  ImuSpi::reinitInterrupts(void) {
+    imuDataReady.fall(this, &ImuSpi::DataReadyISR);
+}
+
+// initialize the IMU
+void ImuSpi::InitImu(void) {
+    // deselect the IMU
+    cs = 1;
+    reset = 1;
+    // perform a hard reset
+    reset = 0; wait(.1); reset = 1;    
+    // send initialization commands
+    Write(0x34, 0x04); // enable active low data ready on DIO1
+    Write(0x38, 0x00); // Set the FIR filter to its widest possible bandwidth
+}
+
+// read the IMU accelerometer and gyro registers into the pingpong buffer
+void ImuSpi::BurstRead(void) {
+    static int16_t imuRegs[] = {0x04,0x06,0x08,0x0A,0x0C,0x0E,0x3C};
+    int16_t* wp = GetBufferWritePtr();
+    Read(imuRegs[0]); // set up the first register read operation
+    wait(0.000024); // required to meet IMU t(datarate) spec
+    
+    // send register read commands & read the registers
+    for (int i = 1; i <= 6; i++) {
+        *wp++ = Read(imuRegs[i]);
+        wait(0.000024);
+    }
+    *wp = Read(0); // read the last register output
+}
+
+int16_t ImuSpi::Read(char adr) {
+    int16_t cmd = 0x3f00 & (adr << 8);
+    int16_t response;
+    cs = 0;
+    response = spi.write(cmd);
+    cs = 1;
+    return response;
+}
+
+
+void ImuSpi::Write(char adr, char data) {
+    int16_t cmd = 0x8000 | (adr << 8) | data;
+    cs = 0;
+    spi.write(cmd);
+    cs = 1;
+}
+
+bool ImuSpi::IsDataReady(void) {
+    if (dataReady == true) {
+        dataReady = false;
+        return true;
+    } else {
+        return false;
+    }
+}
+
+void ImuSpi::DataReadyISR(void) {
+diag = 1;
+    TogglePingpong();
+    dataReady = true;
+diag = 0;
+}

diff -r 000000000000 -r c6ee363ac724 imu-spi.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/imu-spi.h	Wed Aug 10 21:50:36 2011 +0000
@@ -0,0 +1,31 @@
+//
+// imu-spi.h
+//
+// copyright 2010 Hugh Shane
+//
+
+class ImuSpi {
+private:
+    const static int bufferSize = 7;
+    int16_t buffer[2][bufferSize]; // ping-pong IMU data buffer
+    unsigned pingpong;
+    bool dataReady;
+    SPI spi; 
+    DigitalOut cs; 
+    DigitalOut reset; 
+    DigitalOut diag; 
+    InterruptIn imuDataReady;
+    void InitImu(void);
+    void DataReadyISR(void);
+    int16_t Read(char);
+    void Write(char, char);        
+    void TogglePingpong() {pingpong = (~pingpong) & 1U;}; 
+    int16_t* GetBufferWritePtr() {return buffer[pingpong & 1U];};
+public:
+    ImuSpi(void);  
+    void BurstRead(void);
+    int16_t* GetBufferReadPtr() {return buffer[(~pingpong) & 1U];};    
+    bool IsDataReady(void);
+    int GetBufferSize(void) {return bufferSize*sizeof(int16_t);};
+    void reinitInterrupts(void);
+};
\ No newline at end of file

diff -r 000000000000 -r c6ee363ac724 main.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Wed Aug 10 21:50:36 2011 +0000
@@ -0,0 +1,51 @@
+//
+// main.cpp
+//
+// Container class for mbed-based ADIS16355 IMU data acquisition system
+//
+// copyright 2010 Hugh Shane
+//
+#include "mbed.h"
+#include "imu-spi.h"
+#include "usb-serial.h"
+
+int main() {
+    DigitalOut diag_led(LED1);          
+    ImuSpi imu;
+    usb_serial_init();
+    char* imubuffer;
+    bool overflow;
+    Timer timer;
+    timer.start();
+    int now, last = 0, elapsed;
+    int nbytes = 12;
+     
+    while (1) {
+    
+        // acquire the IMU data
+        while (!imu.IsDataReady()) {} // wait for the IMU data-ready signal
+        now = timer.read_us(); // grab the elapsed time in microseconds
+        elapsed = now - last;
+        last = now;
+        imu.BurstRead(); // read the IMU output data registers
+        imubuffer = (char*)imu.GetBufferReadPtr(); // get a pointer to the IMU output data
+        
+        // transmit a data packet on the USB serial port
+        overflow = usb_serial_putc(0x55); // start of packet
+        overflow = usb_serial_putc((uint8_t)elapsed); // time marker, just the lower bits
+        
+        for (int i = 0; i < nbytes; i++) {
+            overflow = usb_serial_putc(*imubuffer++); // IMU data
+        }
+        
+        overflow = usb_serial_putc(0xAA); // end of packet
+
+        // diagnostic LED
+        if (overflow)
+            diag_led = 1;
+        else
+            diag_led = 0;
+            
+    }
+
+}
\ No newline at end of file

diff -r 000000000000 -r c6ee363ac724 mbed.bld
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed.bld	Wed Aug 10 21:50:36 2011 +0000
@@ -0,0 +1,1 @@
+http://mbed.org/users/mbed_official/code/mbed/builds/e2ac27c8e93e

diff -r 000000000000 -r c6ee363ac724 usb-serial.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/usb-serial.cpp	Wed Aug 10 21:50:36 2011 +0000
@@ -0,0 +1,65 @@
+#include "mbed.h"
+#include "usb-serial.h"
+
+volatile unsigned wp, rp;
+static const int outbuf_size = 128;
+static const unsigned pointer_mask = 0x007fU;
+char usb_outbuf[outbuf_size];
+static bool overflow;
+DigitalOut mydiag(p22);;
+
+extern "C" static void txReadyISR() __irq {
+
+    mydiag = 1;
+    // If the output buffer has data, copy the head to the UART
+    if (rp != wp) {
+        LPC_UART0->THR = usb_outbuf[rp];
+        rp = (rp+1) & pointer_mask;
+    }
+    
+    // If the output buffer is empty, disable the transmit buffer empty 
+    // interrupt
+    if (rp == wp)
+       LPC_UART0->IER = 0;
+
+
+    mydiag = 0;
+}
+
+void usb_serial_init(void) {
+    
+    // init the output FIFO
+    wp = 0; rp = 0;
+    overflow = false;
+
+    // init the serial port
+    Serial usb_serial(USBTX, USBRX);    
+    usb_serial.baud(/*115200*/230400);
+    usb_serial.format(8, Serial::None, 1);
+    LPC_UART0->FCR = 7UL;
+    NVIC_SetVector(UART0_IRQn, (uint32_t)txReadyISR);
+    NVIC_EnableIRQ(UART0_IRQn);
+    LPC_UART0->THR = 0; // this is required to start the interrupts, don't understand why
+}
+
+bool usb_serial_putc(char c) {
+
+    if (overflow == false) {
+        usb_outbuf[wp] = c;      
+        LPC_UART0->IER = 0; // ---- critical
+        wp = (wp+1) & pointer_mask;
+
+        if (wp == rp)
+            overflow = true;
+        else
+            overflow = false;
+
+        LPC_UART0->IER = 2UL;  // ---- \critical
+    } else {
+        // reinit the output FIFO
+        wp = 0; rp = 0;
+        overflow = false;
+    }
+    
+    return overflow;
+}
\ No newline at end of file

diff -r 000000000000 -r c6ee363ac724 usb-serial.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/usb-serial.h	Wed Aug 10 21:50:36 2011 +0000
@@ -0,0 +1,2 @@
+void usb_serial_init(void);
+bool usb_serial_putc(char);
\ No newline at end of file