Helmut Schmücker / FtControlSet

Receiver interface for the fischertechnik IR control set

Dependencies:   NeedfulThings

Receiver interface for the fischertechnik IR control set.

An mbed port of the code found on this ft community WIKI page The ft IR remote control uses some kind of RC-MM Protocol . When any of the controls is applied the remote control sends updates at a rate of at 1/120ms or 1/90ms depending on the senders frequency setting. Each message delivers the complete remote control status encoded into 30 bits. The structure of the message can be seen in FtControlSetMessage.h.

I assume that the ft control set works fine with standard 38kHz IR detectors. I have used a CHQ0038 from a broken DVD Player. It can be connected directly to the mbed: GND, VCC->3.3V and the signal line to any of the numbered mbed gpios.

The PDM timing of the ft IR control set isn't that exact. Thus receive errors occur quite frequently. I am observing an error rate somewhere between 3% and 5%. This driver "ignores" up to 3 consecutive receive errors, i.e. it just indicates an error but still provides the last correctly received message, before it resets the message to zero after the fourth error.

FtControlSetMessage.h

Committer:
humlet
Date:
2013-03-25
Revision:
6:3cce31050c90
Parent:
3:038f86bac6cc

File content as of revision 6:3cce31050c90:

#ifndef FTCONTROLSETSIGNAL_H
#define FTCONTROLSETSIGNAL_H

#include <cstdint>
#include "mbed.h"

/// interface class that translates the raw message of ft IR remote control
/// @note just a wrapper arround an evil bitfield, not really portable, ... but they are so handy
class FtControlSetMessage
{
    union { 
        //  message structure: 30 payload bits plus 2 status bit added by receiver ISR plus 
        struct { 
            unsigned status:2;      // @see Status
            unsigned tail:1;        // should be 0
            unsigned parity:1;      // set if parity even
            unsigned leftXDir:1;    // direction left x
            unsigned leftYDir:1;    // direction left y
            unsigned rightXDir:1;   // direction right x
            unsigned rightYDir:1;   // direction right y
            unsigned leftXSpd:4;    // speed left x
            unsigned leftYSpd:4;    // speed left y
            unsigned rightXSpd:4;   // speed right x
            unsigned rightYSpd:4;   // speed right y
            unsigned onBut:1;       // ON button
            unsigned offBut:1;      // OFF button
            unsigned switch1:1;     // switch 1
            unsigned switch2:1;     // switch 1
            unsigned header:4;      // should be 8;
        };
        uint32_t m_rawMessage;
    };

public:

    /// Status enum returned by getStatus().
    enum Status {/// everything is fine
        OK=0,       /// wrong header ID
        FrameKO,  /// parity error
        ParityKO  
        //ReceiveKO=1,/// message was corrupted: Wrong number of pulses or bad timing
    } ;

    /// Constructor from raw 32bit message
    FtControlSetMessage(uint32_t rawMessage):m_rawMessage(rawMessage) {};

    /// get x position of left control stick [-15,15]
    int32_t getLeftX()const {
        return leftXDir?leftXSpd:-leftXSpd;
    };
    /// get y position of left control stick [-15,15]
    int32_t getLeftY()const {
        return leftYDir?leftYSpd:-leftYSpd;
    };
    /// get x position of right control stick [-15,15]
    int32_t getRightX()const {
        return rightXDir?rightXSpd:-rightXSpd;
    };
    /// get y position of right control stick [-15,15]
    int32_t getRightY()const {
        return rightYDir?rightYSpd:-rightYSpd;
    };
    /// get state of the ON button
    bool getOnButton()const {
        return onBut;
    };
    /// get state of the OFF button
    bool getOffButton()const {
        return offBut;
    };
    /// get state of switch 1 (Frequency setting)
    bool getSwitch1()const {
        return switch1;
    };
    /// get state of switch 2 (Receiver ID)
    bool getSwitch2()const {
        return switch2;
    };
    /// get Status of this message, see Status
    Status getStatus()const {
        return static_cast<Status>(status);
    };

    /// get message in raw format
    uint32_t getRawMessage()const {
        return m_rawMessage;
    };
};

#endif