Revision 0:d493a3003022, committed 2013-05-21

Comitter:

jose_claudiojr

Date:

Tue May 21 13:51:07 2013 +0000

Commit message:

Example of reading an accelerometer sensor (BMA180)

Changed in this revision

diff -r 000000000000 -r d493a3003022 Accelerometer.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Accelerometer.cpp	Tue May 21 13:51:07 2013 +0000
@@ -0,0 +1,100 @@
+
+#include "Accelerometer.h"
+
+Accelerometer::Accelerometer(BMA180* acceleHardware, float sensitivity)
+{
+    this->acceleHardware = acceleHardware; 
+    this->sensitivity = sensitivity;   
+    updateZeroRates();
+}
+
+Accelerometer::~Accelerometer(void)
+{
+}
+
+void Accelerometer::updateZeroRates()
+{
+    update(253, 10); // Utilizando filtro passa baixa, é necessário 253 amostras para estabilização do filtro.
+    update(200, 10);
+    zeroRateX = rawX;
+    zeroRateY = rawY;
+    zeroRateZ = rawZ;
+    //zeroRateX = 0.0;
+    //zeroRateY = 0.0;
+    //zeroRateZ = 0.0;
+}
+
+void Accelerometer::update()
+{    
+    update(1, 1);
+}
+
+void Accelerometer::update(int samplesSize, int sampleDataRate)
+{   
+    int axes[3] = {0, 0, 0};
+    rawX = 0;
+    rawY = 0;
+    rawZ = 0;
+    
+    for (int i = 0; i < samplesSize; i++)
+    {
+                
+        rawX += (this->acceleHardware->getX() / samplesSize);
+        rawY += (this->acceleHardware->getY() / samplesSize);
+        rawZ += (this->acceleHardware->getZ() / samplesSize);
+        
+        //this->acceleHardware->getOutput(axes);
+        
+        //rawX += ((float)axes[0] / samplesSize);
+        //rawY += ((float)axes[1] / samplesSize);
+        //rawZ += ((float)axes[2] / samplesSize);
+        wait_ms(sampleDataRate);
+    }
+}
+
+float Accelerometer::getAccelerationX()
+{
+    //( * Vref / 1023 – VzeroG) / Sensitivity
+    return ((rawX - zeroRateX) / sensitivity); //Devido a posição da plaquinha, quando se define o zeroRateX, tem que adicionar novamente a gravidade, que está influenciando o X
+}
+
+float Accelerometer::getAccelerationY()
+{
+    return ((rawY - zeroRateY) / sensitivity);
+}
+
+float Accelerometer::getAccelerationZ()
+{
+    return (((rawZ - zeroRateZ) / sensitivity) + 1.0);
+}
+
+float Accelerometer::getRadiansAngleX()
+{
+    float x = getAccelerationX();
+    float z = getAccelerationZ();
+    
+    return (float)atan2(x, z);
+}
+
+float Accelerometer::getRadiansAngleY()
+{
+    float x = getAccelerationX();
+    float y = getAccelerationY();
+    float z = getAccelerationZ();
+    return (float)atan2(y, z);
+}
+
+float Accelerometer::getDegreesAngleX()
+{
+    return (getRadiansAngleX() / Accelerometer::getPI()) * 180.0;
+}
+
+float Accelerometer::getDegreesAngleY()
+{
+    return (getRadiansAngleY() / Accelerometer::getPI()) * 180.0;
+}
+
+float Accelerometer::getPI()
+{
+    return 3.14159265;
+}

diff -r 000000000000 -r d493a3003022 Accelerometer.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Accelerometer.h	Tue May 21 13:51:07 2013 +0000
@@ -0,0 +1,42 @@
+#ifndef ACCELEROMETER_H
+#define ACCELEROMETER_H
+
+#include <math.h>
+
+#include "BMA180.h"
+
+class Accelerometer
+{
+    public:
+        Accelerometer(BMA180* acceleHardware, float sensitivity);
+        ~Accelerometer(void);
+        
+        void updateZeroRates();
+        
+        void update();
+        void update(int samplesSize, int sampleDataRate);
+        
+        float getAccelerationX();
+        float getAccelerationY();
+        float getAccelerationZ();
+        
+        float getRadiansAngleX();
+        float getRadiansAngleY();
+        
+        float getDegreesAngleX();
+        float getDegreesAngleY();
+        
+        static float getPI();
+    
+    private:
+        BMA180* acceleHardware;
+        
+        float sensitivity;        
+        float zeroRateX, zeroRateY, zeroRateZ;
+        
+        float rawX;
+        float rawY;
+        float rawZ;
+};
+
+#endif

diff -r 000000000000 -r d493a3003022 BMA180.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/BMA180.cpp	Tue May 21 13:51:07 2013 +0000
@@ -0,0 +1,173 @@
+#include "mbed.h"
+#include "BMA180.h"
+/* Range em default value: 2g (010) / Resolução do ADC 0.25mg/LSB sensibilidade 4096 (LSBadc/g)
+ * Range Register: 0x35 
+ * Valor Range Resolução ADC (mg/LSB)                                              =================================
+ * 000    1g     0.13                                                              || Prestar atenção nas unidades||
+ * 001  1.5g     0.19                                                              =================================
+ * 010    2g     0.25
+ * 011    3g     0.38
+ * 100    4g     0.50
+ * 101    8g     0.99
+ * 110   16g     1.98
+ */
+BMA180::BMA180(PinName sda, PinName scl): i2c(sda, scl)
+{
+    char rx, temp1, temp2;
+    i2c.frequency(100000);
+    //Testar depois com 400KHz
+    //==========================================================================================================
+    // Read chip_id
+    //==========================================================================================================
+    rx = Read(BMA180_WHO_AM_I);
+    if (rx != BMA180_ID)//ID do chip 
+        printf("\ninvalid chip id %d\r\n", rx);
+    //==========================================================================================================
+    // Set CTRLREG0 0x0D, bit ee_w (0001 0000) to update image and make it possible write in to the chip eeprom
+    //==========================================================================================================
+    rx = Read(BM180_CTRLREG0);
+    rx |= 0x10;   
+    Write(BM180_CTRLREG0, rx);    
+    //Let's confirm
+    rx = Read(BM180_CTRLREG0);
+    temp1 = rx | 0x10;
+    if(rx != temp1)
+        printf("\nee_w bit wasn't changed %d\r\n", rx);  
+    // ee_w bit set, OK
+    //==========================================================================================================
+    // Let's define the low-pass filter's bandwidth to 10Hz (bw<3:0> -> 0000), to reduce noise in the signal
+    // To set the bw bit, we will have to acces the bw_tcs register (0x20) 
+    //==========================================================================================================
+    rx = Read(BM180_BWTCS);
+                                                   // procedure: readed value: i.e 0101 0101     
+    temp1 = 0x00;                                  //                        (AND) 0000 1111 -> (~BWMask)
+    temp1 = temp1 << 4;                            //                              ---------
+    rx &= (~0xF0); //Mask                          //                        (OR)  0000 0101
+    rx |= temp1;                                   //              Wanted Value <-[0000]0000 -> Wanted value with 4's complement
+    Write(BM180_BWTCS, rx);                        //                              --------- 
+    //Let's confirm                                //                              0000 0101 -> Final Value
+    rx = Read(BM180_BWTCS);
+    temp2 = rx;
+    temp1 = 0x00;
+    temp1 = temp1 << 4;
+    temp2 &= (~0xF0); //Mask
+    temp2 |= temp1;
+    if(rx != temp2)
+        printf("\nbw bit wasn't changed %d\r\n", rx);  
+    // low-pass filter's bandwidth defined, OK
+    
+    //==========================================================================================================
+    // Let's set the range to 2g (0x02) in the 
+    //==========================================================================================================
+    rx = Read(BMA180_OLSB1);                       // procedure: value to set with 1's complement 0000 [010]0
+    temp1 = 0x02;                                  //            readed value: i.e 0101 0101 
+    temp1 = temp1 << 1;                            //                        (AND) 1111 0001 -> RangeMask
+    rx &= (~0x0E);                                 //                              ---------
+    rx |= temp1;                                   //                              0101 0001
+    Write(BMA180_OLSB1, rx);                        //                         (OR) 0000 0100 -> Shifted value
+    // Let's confirm                               //                              ---------
+    rx = Read(BMA180_OLSB1);                       //                              0101 0101 -> Final Value
+    temp2 = rx;
+    temp1 = 0x02;
+    temp1 = temp1 << 1;
+    temp2 &= (~0x0E);
+    temp2 |= temp1;
+    if(rx != temp2)
+        printf("\nRange not set %d\r\n", rx); 
+}
+
+void BMA180::Write(char reg, char data)
+{
+    char c_data[2];
+    c_data[0] = reg;
+    c_data[1] = data;
+    i2c.write(BMA180_ADDR, c_data, 2);
+}
+
+char BMA180::Read(char data)
+{       
+    char tx = data;
+    char rx;
+    
+    i2c.write((BMA180_ADDR) & 0xFE, &tx, 1); // 0xFE ensure that the MSB bit is being set to zero (RW=0 -> Writing)
+    i2c.read((BMA180_ADDR) | 0x01, &rx, 1);  // 0x01 ensure that the MSB bit is being set to one  (RW=1 -> Reading)
+                                             // The read/write method of I2C does this automatically, so it's useless to set manually                                           
+    return rx;
+}
+
+void BMA180::MultiByteRead(char address, char* output, int size) 
+{
+    i2c.write( (BMA180_ADDR) & 0xFE, &address, 1);      //tell it where to read from
+    i2c.read( (BMA180_ADDR) | 0x01 , output, size);     //tell it where to store the data read
+}
+
+float BMA180::getX()
+{
+    char lsb_byte = 0;
+    signed short msb_byte;
+    float acc;
+    
+    while (lsb_byte != 1)
+    {
+        lsb_byte = Read(BMA180_XLSB) & 0x01;
+    }
+        
+    lsb_byte = Read(BMA180_XMSB);
+    msb_byte = lsb_byte << 8;
+    msb_byte |= Read(BMA180_XLSB);
+    msb_byte = msb_byte >> 2; // Get rid of two non-value bits in LSB
+    //printf("%d \t", msb_byte);
+    acc = (float)msb_byte;
+    return acc;
+}
+
+float BMA180::getY()
+{
+    char lsb_byte = 0;
+    signed short msb_byte;
+    float acc;
+    
+    while (lsb_byte != 1)
+    {
+        lsb_byte = Read(BMA180_YLSB) & 0x01;
+    }
+        
+    lsb_byte = Read(BMA180_YMSB);
+    msb_byte = lsb_byte << 8;
+    msb_byte |= Read(BMA180_YLSB);
+    msb_byte = msb_byte >> 2; // Get rid of two non-value bits in LSB
+    //printf("%d \t", msb_byte);
+    acc = (float)msb_byte;
+    return acc;
+}
+
+float BMA180::getZ()
+{
+    char lsb_byte = 0;
+    signed short msb_byte;
+    float acc;
+    
+    while (lsb_byte != 1)
+    {
+        lsb_byte = Read(BMA180_ZLSB) & 0x01;
+    }
+        
+    lsb_byte = Read(BMA180_ZMSB);
+    msb_byte = lsb_byte << 8;
+    msb_byte |= Read(BMA180_ZLSB);
+    msb_byte = msb_byte >> 2; // Get rid of two non-value bits in LSB
+    //printf("%d \t", msb_byte);
+    acc = (float)msb_byte;
+    return acc;
+}
+
+void BMA180::getOutput(int* readings)
+{
+    char buffer[6];    
+    MultiByteRead(BMA180_XLSB, buffer, 6);
+    
+    readings[0] = (int)buffer[1] << 8 | (int)buffer[0];
+    readings[1] = (int)buffer[3] << 8 | (int)buffer[2];
+    readings[2] = (int)buffer[5] << 8 | (int)buffer[4];
+
+}
\ No newline at end of file

diff -r 000000000000 -r d493a3003022 BMA180.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/BMA180.h	Tue May 21 13:51:07 2013 +0000
@@ -0,0 +1,38 @@
+#ifndef MBED_BMA180_H
+#define MBED_BMA180_H
+
+#define BMA180_WHO_AM_I 0x00
+#define BMA180_ID       0x03
+#define BMA180_ADDR     0x80 //datasheet says 0x40 !
+#define BMA180_XLSB     0x02 //LSB
+#define BMA180_XMSB     0x03 //MSB
+
+#define BMA180_YLSB     0x04 //LSB
+#define BMA180_YMSB     0x05 //MSB
+
+#define BMA180_ZLSB     0x06 //LSB
+#define BMA180_ZMSB     0x07 //MSB
+
+#define BM180_CTRLREG0  0x0D
+#define BM180_BWTCS     0x20
+#define BMA180_OLSB1    0x35
+
+#include "mbed.h"
+
+class BMA180 {
+public:
+    BMA180(PinName sda, PinName scl);
+    
+    float getX();
+    float getY();
+    float getZ();
+    void getOutput(int* readings);  
+private:
+    void Write(char reg, char data);
+    char Read(char);
+    void MultiByteRead(char address, char* output, int size); 
+    I2C i2c;
+    int16_t x,y,z;
+};
+
+#endif

diff -r 000000000000 -r d493a3003022 SerialBuffered.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/SerialBuffered.cpp	Tue May 21 13:51:07 2013 +0000
@@ -0,0 +1,180 @@
+#include "SerialBuffered.h"
+
+/**
+ * Create a buffered serial class.
+ *
+ * @param tx A pin for transmit.
+ * @param rx A pin for receive.
+ */
+SerialBuffered::SerialBuffered(PinName tx, PinName rx) : Serial(tx, rx)
+{
+    indexContentStart = 0;
+    indexContentEnd = 0;
+    timeout = 1;
+    
+    attach(this, &SerialBuffered::handleInterrupt);
+}
+
+/**
+ * Destroy.
+ */
+SerialBuffered::~SerialBuffered()
+{
+}
+
+/**
+ * Set timeout for getc().
+ *
+ * @param ms milliseconds. (-1:Disable timeout)
+ */
+void SerialBuffered::setTimeout(int ms)
+{
+    timeout = ms;
+}
+
+/**
+ * Read requested bytes.
+ *
+ * @param bytes A pointer to a buffer.
+ * @param requested Length.
+ *
+ * @return Readed byte length.
+ */
+size_t SerialBuffered::readBytes(uint8_t *bytes, size_t requested)
+{
+    int i = 0;
+    
+    while (i < requested)
+    {
+        int c = getc();
+        
+        if (c < 0)
+        {
+            break;
+        }
+        
+        bytes[i] = c;
+        i++;
+    }
+    
+    return i;
+}
+
+/**
+ * Get a character.
+ *
+ * @return A character. (-1:timeout)
+ */
+int SerialBuffered::getc()
+{
+    timer.reset();
+    timer.start();
+    
+    while (indexContentStart == indexContentEnd)
+    {
+        wait_ms(1);
+        
+        if ((timeout > 0) && (timer.read_ms() > timeout))
+        {
+            /*
+             * Timeout occured.
+             */
+            // printf("Timeout occured.\n");
+            return EOF;
+        }
+    }
+    
+    timer.stop();
+
+    uint8_t result = buffer[indexContentStart++];
+    indexContentStart =  indexContentStart % BUFFERSIZE;
+
+    return result;
+}
+
+/**
+ * Returns 1 if there is a character available to read, otherwise.
+ */
+int SerialBuffered::readable()
+{
+    return indexContentStart != indexContentEnd;
+}
+
+void SerialBuffered::handleInterrupt()
+{
+    while (Serial::readable())
+    {
+        if (indexContentStart == ((indexContentEnd + 1) % BUFFERSIZE))
+        {
+            /*
+             * Buffer overrun occured.
+             */
+            // printf("Buffer overrun occured.\n");
+            Serial::getc();
+        }
+        else
+        {
+            buffer[indexContentEnd++] = Serial::getc();
+            indexContentEnd = indexContentEnd % BUFFERSIZE;
+        }
+    }
+}
+
+float SerialBuffered::f_readIntTo(char delimiter)
+{
+    char buffer[16];
+    int i;
+    float result;
+    for (i = 0;; i++)
+    {
+        //while (!readable());
+        
+        char number = getc();
+        
+        if (number == delimiter)
+            break;
+            
+        buffer[i] = number;     
+    }
+    
+    buffer[i-1] = '\0';
+    
+    result = atof(buffer);
+    
+    return result;
+}
+
+
+int SerialBuffered::i_readIntTo(char delimiter)
+{
+    char buffer[16];
+    int i;
+    float result;
+    for (i = 0;; i++)
+    {
+        //while (!readable());
+        
+        char number = getc();
+        
+        if (number == delimiter)
+            break;
+            
+        buffer[i] = number;     
+    }
+    
+    buffer[i-1] = '\0';
+    
+    result = atoi(buffer);
+    
+    return result;
+}
+
+void SerialBuffered::writeText(char* text)
+{
+    for (int i = 0; text[i] != '\0' && i < BUFFER_TEXT_SIZE; i++)
+    {    
+        while (!Serial::writeable());
+
+        Serial::putc(text[i]);
+    }
+}

diff -r 000000000000 -r d493a3003022 SerialBuffered.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/SerialBuffered.h	Tue May 21 13:51:07 2013 +0000
@@ -0,0 +1,71 @@
+#ifndef _SERIAL_BUFFERED_H_
+#define _SERIAL_BUFFERED_H_
+
+#include "mbed.h"
+
+/**
+ * Buffered serial class.
+ */
+class SerialBuffered : public Serial
+{
+    public:
+        /**
+         * Create a buffered serial class.
+         *
+         * @param tx A pin for transmit.
+         * @param rx A pin for receive.
+         */
+        SerialBuffered(PinName tx, PinName rx);
+
+        /**
+         * Destroy.
+         */
+        virtual ~SerialBuffered();
+
+        /**
+         * Get a character.
+         *
+         * @return A character. (-1:timeout)
+         */
+        int getc();
+
+        /**
+         * Returns 1 if there is a character available to read, otherwise.
+         */
+        int readable();
+
+        /**
+         * Set timeout for getc().
+         *
+         * @param ms milliseconds. (-1:Disable timeout)
+         */
+        void setTimeout(int ms);
+
+        /**
+         * Read requested bytes.
+         *
+         * @param bytes A pointer to a buffer.
+         * @param requested Length.
+         *
+         * @return Readed byte length.
+         */
+        size_t readBytes(uint8_t *bytes, size_t requested);
+        
+        float f_readIntTo(char delimiter);
+        int i_readIntTo(char delimiter);
+        void writeText(char* text);
+
+    private:
+        void handleInterrupt();
+        
+        static const int BUFFERSIZE = 2048;
+        static const int BUFFER_TEXT_SIZE = 255;
+        
+        uint8_t buffer[BUFFERSIZE];            // points at a circular buffer, containing data from m_contentStart, for m_contentSize bytes, wrapping when you get to the end
+        uint16_t indexContentStart;   // index of first bytes of content
+        uint16_t indexContentEnd;     // index of bytes after last byte of content
+        int timeout;
+        Timer timer;
+};
+
+#endif

diff -r 000000000000 -r d493a3003022 main.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp	Tue May 21 13:51:07 2013 +0000
@@ -0,0 +1,43 @@
+#include "mbed.h"
+#include "BMA180.h"
+#include "Accelerometer.h"
+
+#define SDA      p9
+#define SCL      p10
+Serial pc(USBTX, USBRX);
+//Serial pc(p28, p27);
+int main() 
+{
+    float x,y,z, AngleX, AngleY;
+    pc.printf("Inicializing...\r\n");
+    BMA180 *bma180 = new BMA180(SDA, SCL);
+    Accelerometer acc(bma180, 4096);
+    
+    pc.printf("OK...\r\n");
+    wait(1);
+    //max G
+    
+    //y = bma180->getY();
+    //z = bma180->getZ();
+     
+    //printf("%f\n%f\n%f", x,y,z);
+    
+    
+    //acc->updateZeroRates();
+    
+    while(1) 
+    {
+        acc.update();
+        x = acc.getAccelerationX();
+        y = acc.getAccelerationY();
+        z = acc.getAccelerationZ(); 
+        
+        AngleX = acc.getDegreesAngleX();
+        AngleY = acc.getDegreesAngleY();
+        
+        pc.printf("x: %.2f \t\ty: %.2f \t\tz: %.2f \t\tAngleX: %.2f \t\tAngleY: %.2f \t\r\n", x, y, z, AngleX, AngleY); 
+        //x = bma180->getX();
+        //printf("%f\r\n", x);
+        wait_ms(200);
+    }
+}

diff -r 000000000000 -r d493a3003022 mbed.bld
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbed.bld	Tue May 21 13:51:07 2013 +0000
@@ -0,0 +1,1 @@
+http://mbed.org/users/mbed_official/code/mbed/builds/10b9abbe79a6
\ No newline at end of file