File content as of revision 7:ea2799ec389d:

//This is the reference version


/****************************** Apple TV Remote Decoder  and Preamp Controller V1.0 *************************/
/*                                  Andrew C. Russell (c) August 2022                                  */
/* This Apple TV Remote decoder works by reading in the IR stream from one of the serial port lines        */
/* and saving the incoming stream into  an array called stream, after which it is decoded and   */
/* the command executed.                                                */

/* The following audio preamplifier facilities  are catered for:-                               */
/* 1. Manual/Remote volume control adjustment via ALPS RK27 motorized potentiometer             */
/* 2. Input select via rotary encoder                                                           */
/* 3. Output mute via push button actuation                                                     */
/* 4. Record loop via push button actuation                                                     */
/* 5. Power ON output to drive the /standby input of a system power supply                      */
/* Facilities 1,2,3 and 5 are supported by an Apple TV remote                                   */
/* The controller pin definitions are set in Pindef1114.h file.                                 */


// UPDATE 26 July 2018: tone functionality removed. The associated pin (dp25) has been sequestrated
// for the standby output to drive a power amplifier. Pin 8 on J2 (Controller board)

#include "mbed.h"
#include "rc5codes.h"      // RC code definitions - in this case for Apple TV Remote
#include "Pindef1114.h"    // all microcontroller I/O pin assignments defined here    

#define TRUE 1
#define FALSE 0
#define HIGH 1
#define LOW 0
#define tick 280            // quarter bit time in us 
#define tock  1120          // one bit time in us
#define VUP_timeout 45      // defines max number of R/C cycles before the vol ctrl mtr drive stops
#define VDWN_timeout 45     // as above but for volume decrease
// Needed to ensure the motor is not burnt out
#define DEBOUNCE 20000         // this is the switch debounce time

// PHONO_   1               // these are the input assignments written out
// CD       2               // on select_out - see thePindef1114.h file for details
// TUN      4
// MSERV    8
// AUX      16
// RECORDER 32
/******************************************************************************************/
DigitalOut FWD1(dp1);       // these are the motor 'H' bridge drive signals
DigitalOut REV1(dp2);       // when the volume controll motor is not being driven
                            // they are all OFF

DigitalOut muteout(dp13);    // drives the mute relay via a mosfet or transistor
DigitalOut muteLED(dp14);
//InterruptIn mute_int(dp11);  // mute p/button interrupt
//DigitalIn mute(dp11);         // mute input from associated pushbutton

DigitalOut stby_pa(dp25);    //   power amplifier standby control which follows the premap
                            // but with suitable delays                       
                            
InterruptIn rc5int(dp17);    // this is the R/C interrupt triggered by the IRx data out
DigitalIn rc5dat(dp17);      // data is read in from here - its coming from the IRx data out


InterruptIn select_int(dp28); // select rotary encoder interrupt - we use the 'A' O/P to generate the interrupt
DigitalIn sela(dp28);         // select input rotary enc input A
DigitalIn selb(dp27);         // select input rotary enc input B

DigitalIn stdby(dp26);       // standby function p/button input
InterruptIn stdby_int(dp26); // standby p/button interrupt in


//InterruptIn tone_pb(dp15);
//DigitalIn tone(dp15);
//DigitalOut tone(dp25);          // can only be turned on and off at this stage by the r/control

//InterruptIn recloop_int(dp14);   //record loop interrupt
//DigitalIn recloop_in(dp14);      // record loop p/button input
//DigitalOut recloop_out(dp16);    // drives record loop LED
//DigitalOut recloop_rly(dp10); 

BusOut select_drv(dp11,dp4, dp5, dp6, dp9, dp10);  //these are the select relay drivers

/*******************************************************************************************/


int startbit;
int toggle;                 // this is the 3rd bit position in the input stream and checks for
// subsequent button depresses from the r/control
int toggle1;                // temorary storage in the volume UP and volume DOWN functions
int toggle2;                // temprary storage of the PB in the mute function
int toggle3;                // temp storage for the r/control tone in-out function
int standby;
int command = 0;
int vendor_id = 0;
int pair_command = 0;
int address = 0;
int stop_bit = 0;
int recloop_status = 0;
int FLAG1;                  // this is used in the remote control input processing
int FLAG2;                  // this is used in the select input processing
int FLAG3;                  // this is for the mute pushbutton
int FLAG4;                  // this is for the standby pushbutton
// int FLAG5;                  // this is the recloop flag
int RCFLAG = FALSE;         // used to determine if the select command came via R/C
int REPEATFLAG;             // repaet command flag used for volume control
//int FLAGVOLUP;
//int FLAGVOLDWN;
//int FLAG7 = FALSE;          // thyis flag is set to TRUE if recloop is active
int standbyflag;            // used to save the standby condition
int RECLOOP1 = 16;          // this is the bus address 1 before the Recorder
int RECLOOP2 = 32;          // this is the bus address for the Recorder input
// and is used in the recloop service routine
int muteflag = FALSE;        // use to control mute and mute indicatoe independently
//int recloop_status = 32;    // this is the initial value. This variable is used
// in the select_out routine to indicate when the
// input select should wrap around dependent upon
// whether the record loop has been activated.
int relay;
int key_press = 1;          // keeps track of key presses
int REPEAT = 511;         // this is the repeat code for volup and voldown
int COMSTORE = 0;           // store the previous command

// delcarations below are all for the input select proceses
int select = 0;
int select_save = 2;        // we save the status of select drive here. Initial setting is for CD
int select_rot;             // rotary encoder pulse counter

// declare function prototypes here
void select_out (void);     // writes selected input out to the select_drv bus
void select_isr(void);
void rc5isr(void);          // RC5 ISR for remote control
void mute_isr(void);
void mute_sel(void);        //mutes select relays for a few ms during select
//void recloop_isr(void);
void standby_out(void);

/****************************** volume increase ***********************************/
void vol_up (void)
{
    if ((standbyflag == TRUE) && (key_press < VUP_timeout)) {
       FWD1 = HIGH;
       wait_us(100000);           //drive the motors for a short while
        } 
       FWD1 = LOW;

   // }
  //  if (toggle1 != toggle) {
  //      key_press = 0;      // user released the button, so reset counter
  //  } else if (toggle1 == toggle) {
  //      key_press++;        // button remained depressed, so increment counter
   //}
 ////   toggle1 = toggle;
    wait_us(1000);
}

/******************************* volume decrease **********************************/
void vol_dwn (void)
{
    if ((standbyflag == TRUE) && (key_press < VDWN_timeout)) {
        REV1 = HIGH; 
        wait_us(1000);           //drive the motors for a short while
        }
        REV1 = LOW;
 //   }
 //   if (toggle1 != toggle) {
 //       key_press = 0;      // user released the button, so reset counter
 //   } else if (toggle1 == toggle) {
 //       key_press++;        // button remained depressed, so increment counter
 //   }
  //  toggle1 = toggle;
    wait_us(1000);
}

/********************************** stdby_isr *************************************/
void stdby_isr(void)
{
    FLAG4 = TRUE;
}

/*********************************** standby **************************************/
/* this will require supporting hardware functionality to power down the          */
/* analog board, LED's etc. Best option here is to use regulators with a          */
/* shutdown option. for now,  all the LED's are just turned off                   */
/* and input relays and mute relayes disabled.                                    */

void standby_out(void)      // both p/button and R/C come in here
{
    __disable_irq();
    stdby_int.fall(NULL);   // on first power up cycle NO interrupts are accepted
    wait_us(DEBOUNCE);       // a very simple debounce
    do {                    // that waits for the depressed button to be released
        continue; //(1);a
    } while (stdby != 1);

    if (standbyflag == TRUE) {      // was ON so now turn it OFF
        stby_pa = HIGH;             // turn the trigger output OFF
        wait_us(1000000); //make sure power amp has powered down
         muteLED = HIGH;                   
        muteout = LOW;              // now mute the preamp
        wait_us(3000000);
        // turn off all interrupts except the standby and rc5int
        select_int.fall(NULL);
        select_save = select_drv;   // save the status of select_drv
        select_drv = 0;             // all input select relays are OFF
        standbyflag = FALSE;
        muteflag = FALSE;
       muteLED = LOW;
    }


    else if (standbyflag == FALSE) {// was OFF so we will turn it ON

        muteLED = HIGH;              // turn the mute indicator ON
        rc5int.rise(&rc5isr);       // trigger int on rising edge - go service it at rc5dat
        select_int.fall(&select_isr);   // input from rotary encoder or input select
        wait_us(100000);
        select_drv = select_save;   // recall the input select setting and write to output
        wait_us(2000000);                    // let things settle a bit
        muteout = HIGH;             // enable output
       muteflag = FALSE;
        muteLED = LOW;             // turn the mute indicator OFF
        standbyflag = TRUE;
        wait_us(3000000); // make sure preamp has settled before powering power amp ON
        stby_pa = LOW;             // now power up the amplifier
    }
    wait_us(500000);                   // let things settle a bit
    __enable_irq();
    stdby_int.fall(&stdby_isr);     // re-enable the standby interrupt

}

/************************************** mute  ************************************/
void mute_out()
{
    
    if (muteflag == FALSE) {    // mute was inactive so it will now get activated
        wait_us(100000);
        muteout = LOW;
        muteLED = HIGH;
        muteflag = TRUE;        // indicate its been activated
    }

    else if (muteflag == TRUE) {   //it was active, so it must be deactivated here
        wait_us(100000);
        muteout = HIGH;
        muteLED = LOW;
        muteflag = FALSE;
    }

    wait_us(800000);               // make sure relay state is settled

}

/************************************ rc5isr **************************************/
/* Interrupt triggered by a rising edge on p21 which is R/C data in               */

void rc5isr(void)
{
    FLAG1 = TRUE;
    RCFLAG = TRUE;
  
}

/******************* save bit stream from remote controller ***********************/
/* This function reads the input data on pin rc5dat at 1120us ('tock')intervals   */
/* and saves the data into an array stream[i].                                    */

void save_stream(void)
{
    if (RCFLAG == TRUE) {
        wait_us(13500); // this is the AGC header - ignore
    }

    bool stream[32];// the array is initialized each time it is used and is local only
    int bitloop;    // number of bit positions
    int i = 0;      // counter
    int k = 0;      // temp storage
    vendor_id = 0;
    pair_command = 0;
    address = 0;
    command = 0;
    stop_bit = 0; //must always return a 1 to be valid, so reset it
    wait_us(tick);   // locate read point in middle of 1st half bit time of the 1st start bit

    for (bitloop = 0; bitloop <32; bitloop ++) {

        stream[bitloop] = rc5dat;  //read the data and save it to array position [i]
//        bitstream = !bitstream; // RC bitstream moinitor on pin 14
        if (rc5dat == HIGH) {
            wait_us(tock);
        }

        wait_us(tock); //wait here until ready to read the next bit in
    }     // now have 31 bits loaded into stream[i]

    /* now put data in the array into the start, toggle, address and command variables - array counts from stream[0] */

    for (i=0; i<11; i++) {   // first 11 bit positions are vendor ID - always 043f for Apple; use for error checking later

        k = stream[i];      // k will hold the vendor ID
        vendor_id = (vendor_id << 1);
        vendor_id = vendor_id|k;

    }

    for (i = 11; i <16; i++) {        // command or pair
        k = stream[i];
        pair_command = (pair_command << 1);
        pair_command = pair_command|k;
    }

    for (i = 16; i <25; i++) {        // device pairing address
        k = stream[i];
        address = (address << 1);
        address = address|k;
    }


    for (i = 25; i <31; i++) {   // bit positions 25 to 30 are the command - 7 bit positions
        k = stream[i];
        command = (command << 1);
        command = command|k;
    }
    stop_bit = stream[31];

 //  printf("\n vendor_id = %d pair_command = %d address = %d command = %d  stop_bit = %d \r", vendor_id, pair_command, address, command, stop_bit);
}

/********************************* process_stream() *******************************/
/* handles commands coming in from the remote controller only                     */

void process_stream (void)
{
    if ((RCFLAG == TRUE) && ((vendor_id == 479) || (vendor_id == 2047)) )  {     
    // basic error checking - must be preamp + startbit ok to get executed otherwise skip completly
 
 if (address == REPEAT) {
     address = COMSTORE; }
 
 
        switch (address) {

            case VUP:
                if (standbyflag == TRUE) {
                vol_up();} 
                 //FLAGVOLUP = TRUE;
                break;

            case VDOWN:
                if (standbyflag == TRUE) {
                    vol_dwn(); } 
               // FLAGVOLDWN = TRUE;
                break;

            case MUTE:
                if (standbyflag == TRUE) {mute_out();}
                break;

            case SELECT_R:
                if (standbyflag == TRUE) { select_out();}
                wait_us(300000);
                break;

            case SELECT_L:
                if (standbyflag == TRUE) { select_out();}
                wait_us(300000);
                break;

            case STANDBY:
                standby_out();
                break;

        }
COMSTORE = address; // save the just execued command

     }
    RCFLAG = FALSE;

}
/*********************************** select_isr ***********************************/

void select_isr(void)
{
    FLAG2 = TRUE;
}

/****************************** mute inter select*********************************/

void mute_sel(void)
{
    select_drv = 0;
    wait_us(2000);
}

/********************************* select_process *********************************/
/* Used for selecting the input source.  This function is used by the             */
/* rotary encoder only                                          */

void select_process(void)
{

    if (RCFLAG == FALSE) {  // if used R/C skip completely - extra safety check
        wait_us(5000); // debounce - very short for the rotary encoder
        select = 0; // flush select

        select = (select | sela) <<1; // read the two port lines associated with the select rotary encoder
        select = (select | selb);


        switch (select) {
            case 1:                 // select encoder is being rotated CW so increment select_rot
                select_rot <<= 1;
                if (select_rot > 32 ) {
                    select_rot = 1;   // wrap around to 1
                }

                break;

            case 0:
                select_rot >>= 1;   // encoder is being rotated CCW so decrement select_rot
                if (select_rot < 1) {
                    select_rot = 32; //wrap around to 32
                }

                break;

            case 2:
                break;   // indeterminate fall through values - ignore
            case 3:
                break;   // and do not change the output
        }
    }

    select_drv = select_rot;   // write the value out to the bus

//    printf("\n RCFLAG %d    select_rot %d \r", RCFLAG, select_rot);
}




/********************************* select_out *********************************/
// this is only  used by the IR remote

void select_out (void)
{

    if (address == SELECT_L) {
        select_rot >>= 1;
        if (select_rot <1) {
            select_rot = 32;
        }
    }


    if (address == SELECT_R) {
        select_rot <<= 1;
        if (select_rot >32) {
            select_rot = 1;
        }

    }

    select_drv = select_rot;   //write the selection out to the bus.

// printf("\n select_rot = %d     select_drv = %d\r", select_rot, select_drv);

}

/************************************ main() ***************************************/
int main(void)
{
 //   Serial pc(USBTX, USBRX);
    __disable_irq();            // just to make sure we can set up correctly without problems
    stby_pa = HIGH;              // make sure the power aamp is OFF
                                 // make sure the power amp is OFF via the trigger output
    muteout = LOW;              //make sure the outputis muted from the get go
   muteLED  = HIGH;             //mute LED must be ON - power up preamble
    select_drv = 0;
   // bitstream = LOW;          // make sure the bitream monitor is LOW
    rc5dat.mode(PullUp);        // pin 17
    sela.mode(PullUp);          // pin 28
    selb.mode(PullUp);          // pin 27
    stdby.mode(PullUp);         // pin 26
    //recloop_in.mode(PullUp);    // pin 14

    wait_us(200000);
    FLAG1 = FALSE;
    FLAG2 = FALSE;
    FWD1=0;                     //make sure the volume control motor is OFF
    REV1=0;

    // set up the ISR's that will be used
    rc5int.fall(&rc5isr);               // trigger int on rising edge - go service it at rc5dat
    select_int.fall(&select_isr);       // input from rotary encoder or input select
    stdby_int.fall(&stdby_isr);         // the system power/standby switch

    //now disable them, leaving only the stand by p/button and rc5int interrupts active
    select_int.fall(NULL);

    standbyflag = TRUE;                 // preamp will be set-up first time for OFF
    standby_out();                      // set system up
    standbyflag = FALSE;
    select_save = 2;
    select_rot = select_save;          // CD will be selected when power is first turned on
    wait_us(1000000);
    muteLED = LOW;
    muteflag = FALSE;
    __enable_irq();

// all ready and in standby from this point forward

LOOP:                                   // this is the main operating loop

   __WFI();                            // wait here until interrupt


    if (FLAG1 == TRUE) {                // FLAG1 indicates remote control was used
        save_stream();
        process_stream();

        FLAG1 = FALSE;
    }

    if (FLAG2 == TRUE) {
        select_process();               //select process
        FLAG2 = FALSE;
    }


    if (FLAG4 == TRUE) {                // standby ON/OFF
        standby_out();
        FLAG4 = FALSE;
    }


    goto LOOP;

}