I'm trying to build communication between arduino & ATTINY814 referring to ONE-WIRE protocol.
It is really difficult for me, there is always miraculous problem before.
This is the basic initial step: server reset -> client presence -> server send CMD
----------------________---____-------___---___---___---___---_---_---_---_--------------------
reset presence 0 0 0 0 1 1 1 1
server client server ->
detect edge: | | | | | |
↑ pull low by client itself, don't detect it
↑ miss signal from here
↑ detect again
The only way to miss the signal should be disabled the interrupt, but did not find the bug to do this.
code :
//ATTINY814 ONE-WIRE simulation
#define OW_BUS_PULLLOW { PORTA_OUTCLR = PIN1_bm; PORTA_DIRSET = PIN1_bm; }
#define OW_BUS_RELEASE { PORTA_DIRCLR = PIN1_bm; }
#define OW_READ ( PORTA_IN & PIN1_bm )
//OW PIN interrupt
#define ENABLE_OW_INT { PORTA_INTFLAGS = PIN1_bm; PORTA_PIN1CTRL |= PORT_ISC_BOTHEDGES_gc; }
#define DISABLE_OW_INT { PORTA_PIN1CTRL &= ~PORT_ISC_BOTHEDGES_gc; }
#define OW_CHECK_TIMEOUT(ticks) { beginCMP2(ticks); }
#define OW_CANCEL_CHECK_TIMEOUT { stopCMP2(); }
#define OW_WAIT_RELEASE_BUS(ticks) { beginCMP1(ticks); }
void TCA_init(){
/* set Normal mode */
TCA0.SINGLE.CTRLB = TCA_SINGLE_WGMODE_NORMAL_gc;
/* disable event counting */
TCA0.SINGLE.EVCTRL &= ~(TCA_SINGLE_CNTEI_bm);
TCA0.SINGLE.CTRLA |= TCA_SINGLE_CLKSEL_DIV8_gc /* System Clock */
| 1 << TCA_SINGLE_ENABLE_bp; /* Module Enable: disabled */
}
void owInit(void) {
owStatus = ST_OW_IDLE;
owIntTriggered = false;
PORTA_PIN1CTRL |= PORT_PULLUPEN_bm; //enable pull up
OW_BUS_RELEASE;
ENABLE_OW_INT;
PORTA_DIRSET = PIN4_bm; //debug
}
void beginCMP1(uint16_t ticksToWait){
TCA0.SINGLE.INTCTRL &= ~TCA_SINGLE_CMP1_bm; //disable CMP1
uint16_t t = TCA0_SINGLE_CNT;
TCA0.SINGLE.CMP1 = t + ticksToWait;
//!!!!!If the timer is running, a compare match sets the flag!!!!!
TCA0.SINGLE.INTFLAGS = TCA_SINGLE_CMP1_bm; //clr int flag
TCA0_SINGLE_INTCTRL |= TCA_SINGLE_CMP1_bm; //enable CMP
}
void beginCMP2(uint16_t ticksToWait){
TCA0.SINGLE.INTCTRL &= ~TCA_SINGLE_CMP2_bm; //disable CMP2
ticksCNTstartCmp2 = TCA0.SINGLE.CNT;
TCA0.SINGLE.CMP2 = ticksCNTstartCmp2 + ticksToWait;
//!!!!!If the timer is running, a compare match sets the flag!!!!!
TCA0.SINGLE.INTFLAGS = TCA_SINGLE_CMP2_bm; //clr int flag
TCA0.SINGLE.INTCTRL |= TCA_SINGLE_CMP2_bm; //enable CMP2
if(TCA0.SINGLE.CMP2<ticksCNTstartCmp2)
ticksWraparoundCmp2 = 0xFFFF - ticksCNTstartCmp2;
else
ticksWraparoundCmp2 = 0;
}
//CMP1 used to release OW bus
ISR(TCA0_CMP1_vect){
OW_BUS_RELEASE;
TCA0.SINGLE.INTCTRL &= ~TCA_SINGLE_CMP1_bm; //disable int
TCA0.SINGLE.INTFLAGS = TCA_SINGLE_CMP1_bm; //clr int flag
//PORTA_OUTSET = PIN4_bm;PORTA_DIRSET = PIN4_bm; //debug
}
//CMP2 used to check timeout
ISR(TCA0_CMP2_vect){
owStatus = ST_OW_IDLE; //timeout ,set to default status: waiting for reset
TCA0.SINGLE.INTCTRL &= ~TCA_SINGLE_CMP2_bm; //disable int
TCA0.SINGLE.INTFLAGS = TCA_SINGLE_CMP2_bm; //clr int flag
//PORTA_OUTSET = PIN4_bm;PORTA_DIRSET = PIN4_bm; //for debug
}
ISR(PORTA_PORT_vect){
if(PORTA_INTFLAGS & PIN1_bm){
owBusLevel = OW_READ;
owIntTriggered = true;
//if(i<40) debuga[i++]=owBusLevel;//！！！！！！！！！！！！！！！！！debug！！！！！！！！！！！！！！！！
PORTA_INTFLAGS = PIN1_bm;
}
}
void statusManager(void){
uint16_t cnt=0;
switch(owStatus){
case ST_OW_IDLE:
if(!owBusLevel){
OW_CHECK_TIMEOUT(OWI_DELAY_H_TICK_MAX);
owStatus = ST_OW_RESET_FALL;
}
break;
case ST_OW_RESET_FALL:
OW_CANCEL_CHECK_TIMEOUT; //stop timeout check
if(owBusLevel){
DISABLE_OW_INT; //don't trigger interrupt by next code(pull low)
OW_BUS_PULLLOW; //presence
ENABLE_OW_INT;
OW_WAIT_RELEASE_BUS(OWI_DELAY_I_TICK_MAX); //presence delay
owStatus = ST_OW_PRESENCE_FALL;
}else
owStatus = ST_OW_IDLE;
break;
case ST_OW_PRESENCE_FALL:
if(owBusLevel){ //presence raise, now sent back presence signal, prepare to receive CMD from server
owAction = OWA_Rcv;
bytesToRcvSend = 1;
curByte = owBuffer+0;
curByteIdx = 0;
curBitIdx = 0;
owStatus = ST_OW_RCV_CMD;
OW_CHECK_TIMEOUT(OWI_TIMEOUT_TICK); // maybe sensor can't receive CMD forever, so it is better to check timeout
}else
owStatus = ST_OW_IDLE;
break;
case ST_OW_RCV_CMD:
OW_CANCEL_CHECK_TIMEOUT; // in order to decrease response time, not check timeout yet
//waiting for 1 bit: fall to raise
if(!owBusLevel){ // fall，start timeout check,and waiting for raise
OW_CHECK_TIMEOUT(OWI_DELAY_C_TICK_MAX); //1:A 0:C,the timeout should be bigger than C
break;
}
//RAISE, 1 bit received, 1/0 check
cnt = TCA0_SINGLE_CNT; //remember current count as soon as possible
//OW_CANCEL_CHECK_TIMEOUT;
cnt = (cnt>ticksCNTstartCmp2) ? (cnt-ticksCNTstartCmp2) : (cnt+ticksWraparoundCmp2);
if(i<40) debuga[i++]=cnt; //！！！！！！！！！！！！！！！！！debug！！！！！！！！！！！！！！！！
if(OW_IS_1(cnt)){
*curByte |= 1<<(curBitIdx);
}else if(OW_IS_0(cnt)){
//do nothing
}else{ //error, reset to IDLE
owStatus = ST_OW_IDLE;
break;
}
//prepare for next bit
if((++curBitIdx)>=8){
if((++curByteIdx)>=bytesToRcvSend){ //received all bytes
owStatus = ST_OW_CMD_RECEIVED;
DISABLE_OW_INT;
beginFlash(); //!!!!!!!!!!!!!!!debug!!!!!!!!!!!!!!!!!!!!!!!!
break;
}
curByte = owBuffer+curByteIdx; //move to new position to save next byte
*curByte = 0; //clear it first
curBitIdx = 0; //reset bit index
}
break;
case ST_OW_CMD_RECEIVED:
//process in main(),too much computation( CRC8 )
break;
case ST_OW_CMD_VERIFIED:
break;
}
}
int main(void){
TCA_init();
owInit();
sei();
while (1){
if(owIntTriggered){
statusManager();
owIntTriggered = false;
}
}
}
Code under ST_OW_RCV_CMD status receive the CMD.
