1-Wire: remove misleading parasitic power function, add byte function

lib/onewire_master.c

@@ -15,7 +15,7 @@
 /** library for 1-wire protocol as master (code)
  *  @file onewire_master.c
  *  @author King Kévin <kingkevin@cuvoodoo.info>
- *  @date 2017
+ *  @date 2017-2018
  *  @note peripherals used: timer @ref onewire_master_timer, GPIO @ref onewire_master_gpio
  *  @note overdrive mode is not provided
  *  @implements 1-Wire protocol description from Book of iButton Standards
@@ -43,14 +43,6 @@
 #define ONEWIRE_MASTER_TIMER 2 /**< timer ID */
 /** @} */
 
-/** @defgroup onewire_master_gpio GPIO used for 1-wire signal
- *  @note external pull-up resistor on pin is required (< 5 kOhm)
- *  @{
- */
-#define ONEWIRE_MASTER_PORT A /**< GPIO port */
-#define ONEWIRE_MASTER_PIN 4 /**< GPIO pin */
-/** @} */
-
 /** state of 1-Wire communication */
 volatile enum {
 	ONEWIRE_STATE_IDLE, /**< no current communication */
@@ -67,43 +59,30 @@ static volatile bool slave_presence = false; /**< if slaves have been detected *
 static uint8_t* buffer = NULL; /**< input/output buffer for read/write commands/functions */
 static uint32_t buffer_size = 0; /**< size of buffer in bits */
 static volatile uint32_t buffer_bit = 0; /**< number of bits read/written */
-static bool onewire_master_parasite = false; /**< if parasite power should be provided whenever the is no communication */
-static uint16_t onewire_master_recovery = 0; /**< the recovery time in us (1 < Trec) */
 
-void onewire_master_setup(bool parasite, uint16_t recovery)
+void onewire_master_setup(void)
 {
 	// setup GPIO with external interrupt
 	rcc_periph_clock_enable(RCC_GPIO(ONEWIRE_MASTER_PORT)); // enable clock for GPIO peripheral
 	gpio_set(GPIO(ONEWIRE_MASTER_PORT),GPIO(ONEWIRE_MASTER_PIN)); // idle is high (using pull-up resistor)
-	onewire_master_parasite = parasite; // save if we should provide parasite power
+	gpio_set_mode(GPIO(ONEWIRE_MASTER_PORT), GPIO_MODE_OUTPUT_50_MHZ, GPIO_CNF_OUTPUT_OPENDRAIN, GPIO(ONEWIRE_MASTER_PIN)); // normal 1-Wire communication (only using external pull-up resistor)
-	// setup GPIO pin as output (master starts communication before slave replies)
-	if (onewire_master_parasite) {
-		gpio_set_mode(GPIO(ONEWIRE_MASTER_PORT), GPIO_MODE_OUTPUT_50_MHZ, GPIO_CNF_OUTPUT_PUSHPULL, GPIO(ONEWIRE_MASTER_PIN)); // provide parasite power (external pull-up resistor is still require for communication)
-	} else {
-		gpio_set_mode(GPIO(ONEWIRE_MASTER_PORT), GPIO_MODE_OUTPUT_50_MHZ, GPIO_CNF_OUTPUT_OPENDRAIN, GPIO(ONEWIRE_MASTER_PIN)); // normal 1-Wire communication (only using external pull-up resistor)
-	}
 	
 	// setup timer to generate/measure signal timing
 	rcc_periph_clock_enable(RCC_TIM(ONEWIRE_MASTER_TIMER)); // enable clock for timer peripheral
 	timer_reset(TIM(ONEWIRE_MASTER_TIMER)); // reset timer state
+	timer_disable_counter(TIM(ONEWIRE_MASTER_TIMER)); // disable timer to configure it
 	timer_set_mode(TIM(ONEWIRE_MASTER_TIMER), TIM_CR1_CKD_CK_INT, TIM_CR1_CMS_EDGE, TIM_CR1_DIR_UP); // set timer mode, use undivided timer clock, edge alignment (simple count), and count up
 	timer_set_prescaler(TIM(ONEWIRE_MASTER_TIMER), 1-1); // don't use prescale since this 16 bits timer allows to wait > 480 us used for the reset pulse ( 1/(72E6/1/(2**16))=910us )
 
 	// use comparator to time signal (without using the output), starting at slot start
+	timer_clear_flag(TIM(ONEWIRE_MASTER_TIMER), TIM_SR_CC1IF); // clear flag
 	timer_set_oc_value(TIM(ONEWIRE_MASTER_TIMER), TIM_OC1, 1*(rcc_ahb_frequency/1000000)-1); // use compare function to time master pulling low when reading (1 < Tlowr < 15)
+	timer_clear_flag(TIM(ONEWIRE_MASTER_TIMER), TIM_SR_CC2IF); // clear flag
 	timer_set_oc_value(TIM(ONEWIRE_MASTER_TIMER), TIM_OC2, 7*(rcc_ahb_frequency/1000000)-1); // use compare function to read or write 0 or 1 (1 < Trw < 15)
+	timer_clear_flag(TIM(ONEWIRE_MASTER_TIMER), TIM_SR_CC3IF); // clear flag
 	timer_set_oc_value(TIM(ONEWIRE_MASTER_TIMER), TIM_OC3, 62*(rcc_ahb_frequency/1000000)-1); // use compare function to end time slot (60 < Tslot < 120), this will be followed by a recovery time (end of timer)
-	timer_set_oc_value(TIM(ONEWIRE_MASTER_TIMER), TIM_OC4, (70-10)*(rcc_ahb_frequency/1000000)-1); // use compare function to detect slave presence (15 < Tpdh < 60 + 60 < Tpdl < 240), with hand tunig
+	timer_clear_flag(TIM(ONEWIRE_MASTER_TIMER), TIM_SR_CC4IF); // clear flag
-	onewire_master_recovery = 5; // set minimum recovery time
+	timer_set_oc_value(TIM(ONEWIRE_MASTER_TIMER), TIM_OC4, (70-10)*(rcc_ahb_frequency/1000000)-1); // use compare function to detect slave presence (15 < Tpdh < 60 + 60 < Tpdl < 240), with hand tuning
-	if (recovery>onewire_master_recovery) { 
-		onewire_master_recovery = recovery; // save desired recovery time
-	}
-	if (UINT16_MAX/onewire_master_recovery<(rcc_ahb_frequency/1000000)) { // catch integer overflow
-		onewire_master_recovery = UINT16_MAX; // save maximum value
-	} else {
-		onewire_master_recovery *= (rcc_ahb_frequency/1000000); // save actual recovery time value
-	}	
-	
 	timer_clear_flag(TIM(ONEWIRE_MASTER_TIMER), TIM_SR_UIF); // clear update (overflow) flag
 	timer_update_on_overflow(TIM(ONEWIRE_MASTER_TIMER)); // only use counter overflow as UEV source (use overflow as start time or timeout)
 	timer_enable_irq(TIM(ONEWIRE_MASTER_TIMER), TIM_DIER_UIE); // enable update interrupt for overflow
@@ -113,6 +92,17 @@ void onewire_master_setup(bool parasite, uint16_t recovery)
 	onewire_master_state = ONEWIRE_STATE_IDLE; // reset state
 }
 
+void onewire_master_release(void)
+{
+	// release timer
+	timer_disable_counter(TIM(ONEWIRE_MASTER_TIMER)); // disable timer
+	timer_reset(TIM(ONEWIRE_MASTER_TIMER)); // reset timer state
+	rcc_periph_clock_disable(RCC_TIM(ONEWIRE_MASTER_TIMER)); // disable clock for timer peripheral
+
+	// release GPIO
+	gpio_set_mode(GPIO(ONEWIRE_MASTER_PORT), GPIO_MODE_INPUT, GPIO_CNF_INPUT_FLOAT, GPIO(ONEWIRE_MASTER_PIN)); // put back to input floating
+}
+
 bool onewire_master_reset(void)
 {
 	// prepare timer
@@ -148,14 +138,8 @@ static bool onewire_master_write(void)
 
 	// prepare timer
 	timer_disable_counter(TIM(ONEWIRE_MASTER_TIMER)); // disable timer to reconfigure it
-	timer_set_counter(TIM(ONEWIRE_MASTER_TIMER),0); // reset counter
+	timer_set_counter(TIM(ONEWIRE_MASTER_TIMER), 0); // reset counter
-	uint16_t timeout = TIM_CCR3(TIM(ONEWIRE_MASTER_TIMER)); // time until new slot (= end of slot+recovery)
+	timer_set_period(TIM(ONEWIRE_MASTER_TIMER), TIM_CCR3(TIM(ONEWIRE_MASTER_TIMER))+2*(rcc_ahb_frequency/1000000)); // set time for new time slot (recovery timer Trec>1, after time slot end )
-	if (UINT16_MAX-timeout<onewire_master_recovery) { // catch integer overflow
-		timeout = UINT16_MAX; // set maximum value
-	} else {
-		timeout += onewire_master_recovery; // add recovery time to end of slot
-	}
-	timer_set_period(TIM(ONEWIRE_MASTER_TIMER), timeout-1); // set time for new time slot (Trec>1, after time slot end and recovery time)
 	timer_clear_flag(TIM(ONEWIRE_MASTER_TIMER), TIM_SR_CC2IF); // clear output compare flag
 	timer_enable_irq(TIM(ONEWIRE_MASTER_TIMER), TIM_DIER_CC2IE); // enable compare interrupt for bit setting
 	timer_clear_flag(TIM(ONEWIRE_MASTER_TIMER), TIM_SR_CC3IF); // clear output compare flag
@@ -188,14 +172,8 @@ static bool onewire_master_read(void)
 
 	// prepare timer
 	timer_disable_counter(TIM(ONEWIRE_MASTER_TIMER)); // disable timer to reconfigure it
-	timer_set_counter(TIM(ONEWIRE_MASTER_TIMER),0); // reset counter
+	timer_set_counter(TIM(ONEWIRE_MASTER_TIMER), 0); // reset counter
-	uint16_t timeout = TIM_CCR3(TIM(ONEWIRE_MASTER_TIMER)); // time until new slot (= end of slot+recovery)
+	timer_set_period(TIM(ONEWIRE_MASTER_TIMER), TIM_CCR3(TIM(ONEWIRE_MASTER_TIMER))+2*(rcc_ahb_frequency/1000000)); // set time for new time slot (recovery timer Trec>1, after time slot end )
-	if (UINT16_MAX-timeout<onewire_master_recovery) { // catch integer overflow
-		timeout = UINT16_MAX; // set maximum value
-	} else {
-		timeout += onewire_master_recovery; // add recovery time to end of slot
-	}
-	timer_set_period(TIM(ONEWIRE_MASTER_TIMER), timeout-1); // set time for new time slot (Trec>1, after time slot end and recovery time)
 	timer_clear_flag(TIM(ONEWIRE_MASTER_TIMER), TIM_SR_CC1IF); // clear output compare flag
 	timer_enable_irq(TIM(ONEWIRE_MASTER_TIMER), TIM_DIER_CC1IE); // enable compare interrupt for stop pulling low
 	timer_clear_flag(TIM(ONEWIRE_MASTER_TIMER), TIM_SR_CC2IF); // clear output compare flag
@@ -221,7 +199,7 @@ uint8_t onewire_master_crc(uint8_t* data, uint32_t length)
 	if (NULL==data || 0==length) { // check input
 		return 0; // wrong input
 	}
-	
+
 	uint8_t crc = 0x00; // initial value
 	for (uint8_t i=0; i<length; i++) { // go through every byte
 		crc ^= data[i]; // XOR byte
@@ -236,12 +214,36 @@ uint8_t onewire_master_crc(uint8_t* data, uint32_t length)
 	return crc;
 }
 
+bool onewire_master_read_byte(uint8_t* data)
+{
+	if (NULL==data) { // check input
+		return false; // wrong input
+	}
+
+	// read data
+	buffer_size = 8; // save number of bits to read (1 byte)
+	buffer = data; // set the buffer to the data to write
+	if (!onewire_master_read()) { // read bits from slave
+		return false; // an error occurred
+	}
+	return true;
+}
+
+bool onewire_master_write_byte(uint8_t data)
+{
+	// send data byte
+	buffer_size = 8; // function command is only one byte
+	buffer = &data; // set the buffer to the function code
+	if (!onewire_master_write()) { // send command
+		return false; // an error occurred
+	}
+	return true;
+}
+
 bool onewire_master_function_read(uint8_t function, uint8_t* data, uint32_t bits)
 {
 	// send function command
-	buffer_size = 8; // function command is only one byte
+	if (!onewire_master_write_byte(function)) {
-	buffer = &function; // set the buffer to the function code
-	if (!onewire_master_write()) { // send command
 		return false; // an error occurred
 	}
 
@@ -262,9 +264,7 @@ bool onewire_master_function_read(uint8_t function, uint8_t* data, uint32_t bits
 bool onewire_master_function_write(uint8_t function, uint8_t* data, uint32_t bits)
 {
 	// send function command
-	buffer_size = 8; // function command is only one byte
+	if (!onewire_master_write_byte(function)) {
-	buffer = &function; // set the buffer to the function code
-	if (!onewire_master_write()) { // send command
 		return false; // an error occurred
 	}
 
@@ -346,7 +346,7 @@ bool onewire_master_rom_search(uint64_t* code, bool alarm)
 				goto end; // an error has occurred
 		}
 		buffer_size = 1; // to send next bit
-		buffer[0] = (*code>>bit); // set bit to send
+		buffer[0] = ((*code)>>bit); // set bit to send
 		if (!onewire_master_write()) { // send bit
 			goto end; // an error has occurred
 		}
@@ -354,7 +354,7 @@ bool onewire_master_rom_search(uint64_t* code, bool alarm)
 	// verify ROM code
 	uint8_t rom_code[8] = {0}; // to store ROM code
 	for (uint8_t i=0; i<LENGTH(rom_code); i++) {
-		rom_code[i] = *code>>(8*i); // split and save last code in ROM code
+		rom_code[i] = (*code)>>(8*i); // split and save last code in ROM code
 	}
 	if (onewire_master_crc(rom_code, LENGTH(rom_code))) { // verify checksum
 		*code = 0; // return the last code found since it's valid
@@ -389,7 +389,6 @@ bool onewire_master_rom_match(uint64_t code)
 	return true;
 }
 
-
 /** interrupt service routine called for timer */
 void TIM_ISR(ONEWIRE_MASTER_TIMER)(void)
 {
@@ -428,11 +427,6 @@ void TIM_ISR(ONEWIRE_MASTER_TIMER)(void)
 				gpio_set(GPIO(ONEWIRE_MASTER_PORT),GPIO(ONEWIRE_MASTER_PIN)); // pull signal high (idle state)
 				onewire_master_state = ONEWIRE_STATE_ERROR; // indicate error
 		}
-		if (onewire_master_parasite && (ONEWIRE_STATE_ERROR==onewire_master_state || ONEWIRE_STATE_DONE==onewire_master_state)) {
-			gpio_set_mode(GPIO(ONEWIRE_MASTER_PORT), GPIO_MODE_OUTPUT_50_MHZ, GPIO_CNF_OUTPUT_PUSHPULL, GPIO(ONEWIRE_MASTER_PIN)); // provide parasite power
-		} else {
-			gpio_set_mode(GPIO(ONEWIRE_MASTER_PORT), GPIO_MODE_OUTPUT_50_MHZ, GPIO_CNF_OUTPUT_OPENDRAIN, GPIO(ONEWIRE_MASTER_PIN)); // normal 1-Wire communication (only using external pull-up resistor)
-		}
 	} else if (timer_get_flag(TIM(ONEWIRE_MASTER_TIMER), TIM_SR_CC1IF)) { // compare event happened for master pull low end for read
 		timer_clear_flag(TIM(ONEWIRE_MASTER_TIMER), TIM_SR_CC1IF); // clear flag
 		switch (onewire_master_state) {
@@ -475,9 +469,6 @@ void TIM_ISR(ONEWIRE_MASTER_TIMER)(void)
 	} else if (timer_get_flag(TIM(ONEWIRE_MASTER_TIMER), TIM_SR_CC3IF)) { // compare event happened for end to time slot
 		timer_clear_flag(TIM(ONEWIRE_MASTER_TIMER), TIM_SR_CC3IF); // clear flag
 		gpio_set(GPIO(ONEWIRE_MASTER_PORT),GPIO(ONEWIRE_MASTER_PIN)); // pull signal high to end time slot
-		if (onewire_master_parasite) { // provide power during recovery time
-			gpio_set_mode(GPIO(ONEWIRE_MASTER_PORT), GPIO_MODE_OUTPUT_50_MHZ, GPIO_CNF_OUTPUT_PUSHPULL, GPIO(ONEWIRE_MASTER_PIN)); // provide parasite power
-		}
 	} else if (timer_get_flag(TIM(ONEWIRE_MASTER_TIMER), TIM_SR_CC4IF)) { // compare event happened for slave presence detection
 		timer_clear_flag(TIM(ONEWIRE_MASTER_TIMER), TIM_SR_CC4IF); // clear flag
 		if (gpio_get(GPIO(ONEWIRE_MASTER_PORT),GPIO(ONEWIRE_MASTER_PIN))) { // check is a slave let its presence know by pulling low

lib/onewire_master.h

@@ -15,18 +15,26 @@
 /** library for 1-wire protocol as master (API)
  *  @file onewire_master.h
  *  @author King Kévin <kingkevin@cuvoodoo.info>
- *  @date 2017
+ *  @date 2017-2018
  *  @note peripherals used: timer @ref onewire_master_timer, GPIO @ref onewire_master_gpio
  *  @note overdrive mode is not provided
  */
 #pragma once
 
-/** setup 1-wire peripheral
+/** @defgroup onewire_master_gpio GPIO used for 1-wire signal
- *  @param[in] parasite enable parasite power (provide power over 1-Wire line when not communicating)
+ *  @note external pull-up resistor on pin is required (< 5 kOhm)
- *  @warning multiple masters and interrupts are prevented when parasite power is used
+ *  @{
- *  @param[in] recovery recovery time in us between timeslot, e.g. to ensure enough parasite power is provided (0 if not required)
  */
-void onewire_master_setup(bool parasite, uint16_t recovery);
+#define ONEWIRE_MASTER_PORT C /**< GPIO port */
+#define ONEWIRE_MASTER_PIN 9  /**< GPIO pin */
+/** @} */
+
+/** setup 1-wire peripheral
+ */
+void onewire_master_setup(void);
+/** release 1-wire peripheral
+ */
+void onewire_master_release(void);
 /** send reset pulse
  *  @return if slaves have indicated their presence
  */
@@ -62,6 +70,18 @@ bool onewire_master_rom_skip(void);
  *  @return if operation succeeded
  */
 bool onewire_master_rom_match(uint64_t code);
+/** read data byte
+ *  @note it is up to the user to send the reset pulse 
+ *  @param[out] data buffer to save data read
+ *  @return if operation succeeded
+ */
+bool onewire_master_read_byte(uint8_t* data);
+/** write data byte
+ *  @note it is up to the user to send the reset pulse 
+ *  @param[in] data byte to write
+ *  @return if operation succeeded
+ */
+bool onewire_master_write_byte(uint8_t data);
 /** issue function and read data
  *  @note user needs to send a ROM command before
  *  @param[in] function function command to send