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Merge pull request #4 from MicroBahner/master

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Update DCC bit decoding
This commit is contained in:
Alex Shepherd
2016-07-23 19:48:42 +12:00
committed by GitHub
parent 47d052a939 e0d46ff9b9
commit 0c3385b27d
2 changed files with 50 additions and 9 deletions
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58
NmraDcc.cpp
View File

@@ -20,6 +20,7 @@
// Experimental Version to support 14 speed steps
// and new signature of notifyDccSpeed and notifyDccFunc
// 2015-12-16 Version without use of Timer0 by Franz-Peter Müller
// 2016-07-16 handle glitches on DCC line
//
//------------------------------------------------------------------------
//
@@ -60,14 +61,14 @@
//
// |<-----116us----->|
// DCC 1: _________XXXXXXXXX_________XXXXXXXXX_________
// |<--------138us------>|
// |<--------146us------>|
// ^-INTx ^-INTx
// less than 138us: its a one-Bit
//
//
// |<-----------------232us----------->|
// DCC 0: _________XXXXXXXXXXXXXXXXXX__________________XXXXXXXX__________
// |<--------138us------->|
// |<--------146us------->|
// ^-INTx ^-INTx
// greater than 138us: its a zero bit
//
@@ -76,8 +77,12 @@
//
//------------------------------------------------------------------------
#define MAX_ONEBITFULL 146
#define MAX_PRAEAMBEL 146 //138
#define MAX_PRAEAMBEL 146
#define MAX_ONEBITHALF 82
#define MIN_ONEBITFULL 82
#define MIN_ONEBITHALF 35
#define MAX_BITDIFF 18
// Debug-Ports
//#define debug // Testpulse for logic analyser
@@ -192,7 +197,7 @@ struct countOf_t countOf;
#endif
static byte ISREdge; // RISING or FALLING
static word bitMax;
static word bitMax, bitMin;
typedef enum
{
@@ -228,6 +233,7 @@ typedef struct
#ifdef DCC_DEBUG
uint8_t IntCount;
uint8_t TickCount;
uint8_t NestedIrqCount;
#endif
}
DCC_PROCESSOR_STATE ;
@@ -240,19 +246,38 @@ void ExternalInterruptHandler(void)
uint8_t DccBitVal;
static int8_t bit1, bit2 ;
static word lastMicros;
static byte halfBit;
static byte halfBit, DCC_IrqRunning;
unsigned int actMicros, bitMicros;
if ( DCC_IrqRunning ) {
// nested DCC IRQ - obviously there are glitches
// ignore this interrupt and increment glitchcounter
CLR_TP3;
#ifdef DCC_DEBUG
DccProcState.NestedIrqCount++;
#endif
SET_TP3;
return; //>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> abort IRQ
}
SET_TP3;
actMicros = micros();
bitMicros = actMicros-lastMicros;
if ( bitMicros < bitMin ) {
// too short - my be false interrupt due to glitch or false protocol -> ignore
CLR_TP3;
SET_TP4;
SET_TP4;
CLR_TP4;
return; //>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> abort IRQ
}
DccBitVal = ( bitMicros < bitMax );
lastMicros = actMicros;
//#ifdef debug
if(DccBitVal) {SET_TP2} else {CLR_TP2};
if(DccBitVal) {SET_TP2;} else {CLR_TP2;};
//#endif
DCC_IrqRunning = true;
sei(); // time critical is only the micros() command,so allow nested irq's
#ifdef DCC_DEBUG
DccProcState.TickCount++;
DccProcState.TickCount++;
#endif
switch( DccRx.State )
@@ -269,6 +294,7 @@ void ExternalInterruptHandler(void)
attachInterrupt( DccProcState.ExtIntNum, ExternalInterruptHandler, CHANGE);
halfBit = 0;
bitMax = MAX_ONEBITHALF;
bitMin = MIN_ONEBITHALF;
CLR_TP1;
}
} else {
@@ -299,12 +325,13 @@ void ExternalInterruptHandler(void)
halfBit = 0;
bit2=bitMicros;
DccRx.BitCount++;
if( abs(bit2-bit1) > 14 ) {
// the length of the 2 halbits differ too much -> wrong protokoll
if( abs(bit2-bit1) > MAX_BITDIFF ) {
// the length of the 2 halfbits differ too much -> wrong protokoll
CLR_TP2;
CLR_TP3;
DccRx.State = WAIT_PREAMBLE;
bitMax = MAX_PRAEAMBEL;
bitMin = MIN_ONEBITFULL;
DccRx.BitCount = 0;
attachInterrupt( DccProcState.ExtIntNum, ExternalInterruptHandler, ISREdge );
SET_TP3;
@@ -320,6 +347,7 @@ void ExternalInterruptHandler(void)
// its a '1' halfbit -> we got only a half '0' bit -> cannot be DCC
DccRx.State = WAIT_PREAMBLE;
bitMax = MAX_PRAEAMBEL;
bitMin = MIN_ONEBITFULL;
DccRx.BitCount = 0;
} else {
// we got two '0' halfbits -> it's the startbit
@@ -327,6 +355,7 @@ void ExternalInterruptHandler(void)
if ( ISREdge == RISING ) ISREdge = FALLING; else ISREdge = RISING;
DccRx.State = WAIT_DATA ;
bitMax = MAX_ONEBITFULL;
bitMin = MIN_ONEBITFULL;
DccRx.PacketBuf.Size = 0;
DccRx.PacketBuf.PreambleBits = 0;
for(uint8_t i = 0; i< MAX_DCC_MESSAGE_LEN; i++ )
@@ -345,11 +374,13 @@ void ExternalInterruptHandler(void)
// second halfbit is 1 -> unknown protokoll
DccRx.State = WAIT_PREAMBLE;
bitMax = MAX_PRAEAMBEL;
bitMin = MIN_ONEBITFULL;
DccRx.BitCount = 0;
} else {
// we got the startbit
DccRx.State = WAIT_DATA ;
bitMax = MAX_ONEBITFULL;
bitMin = MIN_ONEBITFULL;
DccRx.PacketBuf.Size = 0;
DccRx.PacketBuf.PreambleBits = 0;
for(uint8_t i = 0; i< MAX_DCC_MESSAGE_LEN; i++ )
@@ -378,6 +409,7 @@ void ExternalInterruptHandler(void)
{
DccRx.State = WAIT_PREAMBLE ;
bitMax = MAX_PRAEAMBEL;
bitMin = MIN_ONEBITFULL;
DccRx.BitCount = 0 ;
}
else
@@ -395,6 +427,7 @@ void ExternalInterruptHandler(void)
CLR_TP3;
DccRx.State = WAIT_PREAMBLE ;
bitMax = MAX_PRAEAMBEL;
bitMin = MIN_ONEBITFULL;
DccRx.PacketCopy = DccRx.PacketBuf ;
DccRx.DataReady = 1 ;
SET_TP3;
@@ -407,6 +440,7 @@ void ExternalInterruptHandler(void)
}
CLR_TP1;
CLR_TP3;
DCC_IrqRunning = false;
}
void ackCV(void)
@@ -955,6 +989,7 @@ void NmraDcc::init( uint8_t ManufacturerId, uint8_t VersionId, uint8_t Flags, ui
MODE_TP4;
ISREdge = RISING;
bitMax = MAX_ONEBITFULL;
bitMin = MIN_ONEBITFULL;
attachInterrupt( DccProcState.ExtIntNum, ExternalInterruptHandler, RISING);
DccProcState.Flags = Flags ;
@@ -1005,6 +1040,11 @@ uint8_t NmraDcc::getTickCount(void)
return DccProcState.TickCount;
}
uint8_t NmraDcc::getNestedIrqCount(void)
{
return DccProcState.NestedIrqCount;
}
uint8_t NmraDcc::getState(void)
{
return DccRx.State;

1
NmraDcc.h
View File

@@ -203,6 +203,7 @@ class NmraDcc
uint8_t getTickCount(void);
uint8_t getBitCount(void);
uint8_t getState(void);
uint8_t getNestedIrqCount(void);
#endif
};