Diff: Srf0208IF.h

Revision:

2:dfc8b09b4e3b

Parent:

1:32c4dd194228

Child:

3:70c946ba29cc

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Srf0208IF.h	Sun May 26 20:52:27 2013 +0000
@@ -0,0 +1,162 @@
+#ifndef SRF0208IF_H
+#define SRF0208IF_H
+#include "stdint.h"
+
+namespace mbed
+{
+
+class I2CMasterRtos;
+
+/// common base interface class for SRF02 and SRF08 utrasonic rangers
+class Srf0208IF
+{
+protected:
+    int m_adr;
+    I2CMasterRtos& m_i2c;
+ 
+public:
+    
+    /// little helper that translates two raw bytes into a word
+    static int twoByte2int(const char* data){
+        return ((static_cast<uint16_t>(*(data)))<<8) | static_cast<uint16_t>(*(data+1));
+    }
+    /// little helper that translates the us transit time into a distance in mm
+    static int time2dist_us2mm(int us){
+        return us!=-1 ? (us*sonicSpeed)>>1 : us;       
+    }
+
+
+    /// sonic speed in m/s @ 21°C  ...  c=(331.5+0.6*T/°C)m/s
+    /// To calculate the distance in mm: Multiply the µs measurement with this constant and divide by 2
+    static const int sonicSpeed = 344;
+
+    /// The constructor
+    Srf0208IF(int adr, I2CMasterRtos& i2c): m_adr(adr), m_i2c(i2c){};
+
+    /// Trigger ranging. Result can be read back after 66ms via triggerEchoMeasurement()
+    /// @return true on success
+    bool triggerRanging();
+    
+    /// Read back measured transit time in µs of the last triggerRanging() or triggerEchoMeasurement() request.
+    /// Depending on the distance the Measurement takes up to 66ms.
+    /// @return -1 on error
+    int readTransitTime_us();
+
+    /// Read back measured distance in mm of the triggerRanging() or triggerEchoMeasurement() request.
+    /// Depending on the distance the Measurement takes up to 66ms.
+    /// @return -1 on error
+    int readDistance_mm() {
+        return time2dist_us2mm(readTransitTime_us());
+    };
+
+    /// Assign a new adress to the SRF ranger device. Available 8bit addresses: E0, E2, E4 ... FE
+    /// Ensure that only one SRF device is connected to the bus
+    void resetI2CAdress(int newAddress);
+
+    /// Reads the SRF's SW revision
+    /// @return -1 on error
+    int readSWRevision();
+
+    /// Returns true if ranging is done
+    bool rangingCompleted(){
+        return readSWRevision()!=-1;
+    }
+};
+
+/// Provides special features of the SRF02
+class Srf02IF : public Srf0208IF
+{
+public:
+
+    /// The constructor
+    Srf02IF(int adr, I2CMasterRtos& i2c):Srf0208IF(adr,i2c){};
+
+    /// Just send a ping
+    /// @return true on success
+    bool triggerPing();
+
+    /// Just wait for an echo and measure the time
+    /// Result can be read back after 66ms via triggerEchoMeasurement()
+    /// @return true on success
+    bool triggerEchoMeasurement();
+
+    /// Read current minimum range from srf02
+    int readMinimalTransitTime_us();
+    
+    /// Read current minimum range from srf02
+    int readMinimalDistance_mm(){
+        return time2dist_us2mm(readMinimalTransitTime_us());
+    }
+
+};
+
+/// Provides special features of the SRF08
+class Srf08IF : public Srf0208IF
+{
+    char m_rawBuffer[36];
+
+public:
+
+    /// The constructor
+    Srf08IF(int adr, I2CMasterRtos& i2c):Srf0208IF(adr,i2c){};
+
+    /// read light sensor measurement
+    /// @return -1 on error
+    int readBrightness();
+
+    /// trigger ANN mode ranging
+    /// @return true on success
+    bool triggerANNRanging();
+
+    /// Set maximum distance. Use to reduce measurement time.
+    /// @param maxDst maximum distance 0..0xff  (1+maxDst)*43mm  =>  43mm..11m / 3ms..64ms
+    /// @return true on success
+    bool writeMaxDist(int maxDst);
+
+    /// Set/Limit maximum gain. Use to suppress roving echos from previous measurements.
+    /// Necessary at mesurement rates higher than 1/66ms=15Hz.
+    /// During measurement the analog signal amplification is increased every 70µs until
+    /// the maximum gain is reached after 31 steps at ~390mm.
+    /// @param maxGain 0..31 / 0x0..0x1f  =>magic non linear function=> 94..1025 (see SRF08 docu)
+    /// @return true on success
+    bool writeMaxGain(int maxGain);
+
+    /// Get transit time (µs) of n'th echo from internal buffer.
+    /// Call burstRead() before!
+    /// @param echoIdx 0..16
+    int getTransitTimeFromRawBuffer_us(int echoIdx) const {
+        return twoByte2int(&(m_rawBuffer[(++echoIdx)<<1])); // (1+idx)*2
+    }
+    
+    /// Get distanc (mm) of n'th echo from internal buffer.
+    /// Call burstRead() before!
+    /// @param echoIdx 0..16
+    int getDistanceFromRawBuffer_mm(int echoIdx) const {
+        return time2dist_us2mm(getTransitTimeFromRawBuffer_us(echoIdx));
+    }
+    
+    /// Get light sensor data from internal buffer.
+    /// Call burstRead() before!
+    int getBrightnessFromRawBuffer() const {
+        return static_cast<int>(m_rawBuffer[1]);
+    }
+    /// Get ANN data from internal buffer
+    /// Call burstRead() before!
+    /// Each slot is 2048µs/353mm wide.
+    /// @param slotIdx slot 0..31
+    int getANNSlotDataFromRawBuffer(int slotIdx) const {
+        return (static_cast<int>(m_rawBuffer[slotIdx+4]));
+    }
+    /// Reads all data from start to stop register in one go and store it in class internal buffer.
+    /// - reg 0x00: SW Revision
+    /// - reg 0x01: light sensor (SRF08 only)
+    /// - reg 0x02+0x03: range high+low byte
+    /// - reg 0x03+0x04: srf02: min range high+low byte  srf08: 2nd echo
+    /// - reg 0x04+0x05 .. 34+35: 3rd..17th echo high+low byte
+    /// @return true on success
+    bool burstRead(int startReg=1, int stopReg=35);
+};
+
+}
+#endif
+