WebSVN – libIgnTiming – Blame – /trunk/src/rpm.cpp

Rev	Author	Line No.	Line
2	mjames	1	// code to compute RPM
		2	#include "stdint.h"
		3
		4	#include "libIgnTiming/rpm.h"
		5	#if defined RPMTIMER
		6
		7	extern "C"
		8	{
		9	typedef enum
		10	{
		11	PULSE_LOW = 1,
		12	PULSE_HIGH = 2,
		13	PULSE_BOTH = 3
		14	} pulseState_t;
		15	// with a dwell angle of 45 degrees , 4 cylinders and a maximum RPM of 5000
		16	// freq = 5000/60 * 2 = 166Hz.
		17	// the TIM2 counter counts in 10uS increments,
		18	// Need to accumulate low level for a 400th of a second before accepting it as a pulse
		19	const uint16_t ACCUM_MAX = (RPM_COUNT_RATE / 400);
		20
		21	// shared variables used in calculation - a pipeline of samples
		22	static volatile unsigned long RPM_Time[RPM_SAMPLES]; // sampled on both edges
		23	static volatile unsigned long RPM_Count; // incremented every reading
		24
		25	void TIMER_IRQ_HANDLER(void)
		26	{
		27	static char level = 0;
		28	char valid = 0;
		29	uint16_t high_count = 0;
		30	uint16_t low_count = 0;
		31	// rising edge CB pulse
		32	if (__HAL_TIM_GET_FLAG(&TIMER_HANDLE, TIM_FLAG_CC1))
		33	{
		34	__HAL_TIM_CLEAR_FLAG(&TIMER_HANDLE, TIM_FLAG_CC1);
		35	low_count = __HAL_TIM_GET_COMPARE(&TIMER_HANDLE, TIM_CHANNEL_1);
		36	valid = PULSE_LOW; // record we have a low_count val
		37
		38	// trigger any other event at rising edge
		39	AUXILIARY_HIGH;
		40	}
		41	// falling edge trigger CB pulse
		42	if (__HAL_TIM_GET_FLAG(&TIMER_HANDLE, TIM_FLAG_CC2))
		43	{
		44	__HAL_TIM_CLEAR_FLAG(&TIMER_HANDLE, TIM_FLAG_CC2);
		45
		46	high_count = __HAL_TIM_GET_COMPARE(&TIMER_HANDLE, TIM_CHANNEL_2);
		47	valid \|= PULSE_HIGH;
		48	// trigger any other event at falling edge
		49	AUXILIARY_LOW;
		50	}
		51
		52	switch (valid)
		53	{
		54	case pulseState_t::PULSE_LOW:
		55	// count width of a low period
		56	RPM_Time[RPM_Count] = low_count;
		57	RPM_Count = (RPM_Count + 1) % RPM_SAMPLES;
		58	level = 0; // remember level
		59	break;
		60	case pulseState_t::PULSE_HIGH:
		61	// count width of a high period
		62	RPM_Time[RPM_Count] = high_count \| RPM_FLAG;
		63	RPM_Count = (RPM_Count + 1) % RPM_SAMPLES;
		64	level = 1; // remember level
		65	break;
		66	// there has been both a high level and a low level
		67	case pulseState_t::PULSE_BOTH:
		68	if (level == 1) // next level = 0 ,then 1 again
		69	{
		70	RPM_Time[RPM_Count] = low_count;
		71	RPM_Count = (RPM_Count + 1) % RPM_SAMPLES;
		72	RPM_Time[RPM_Count] = high_count \| RPM_FLAG;
		73	RPM_Count = (RPM_Count + 1) % RPM_SAMPLES;
		74	}
		75	else
		76	{
		77	RPM_Time[RPM_Count] = high_count \| RPM_FLAG;
		78	RPM_Count = (RPM_Count + 1) % RPM_SAMPLES;
		79	RPM_Time[RPM_Count] = low_count;
		80	RPM_Count = (RPM_Count + 1) % RPM_SAMPLES;
		81	}
		82	break;
		83	default:
		84	break;
		85	}
		86	}
		87
		88	int CalculateRPM(void)
		89	{
		90	// compute the timer values
		91	// snapshot timers
		92
		93	// Next state of pulse high/low
		94	static unsigned char RPM_State = 1;
		95	// Current state of pulse high/low
		96	static unsigned char RPM_State_Curr = 1;
		97
		98	// variables used in calculation of RPM value
		99	static uint16_t last_dwell_end = 0;
		100	static uint16_t RPM_Period[RPM_AVERAGE];
		101	static unsigned int RPM_Period_Ptr = 0;
		102
		103	static uint16_t RPM_Count_Latch = 0;
		104
		105	// accumulators
		106	static int16_t RPM_Pulsecount = 0;
		107
		108	__disable_irq(); // copy the counter value
		109	// current RPM pulse next slot index
		110	uint16_t RPM_Count_Val = RPM_Count;
		111	__enable_irq();
		112	// do calculations
		113
		114	// if there is only one entry, cannot get difference
		115	if (RPM_Count_Latch != RPM_Count_Val)
		116	{
		117	while (1)
		118	{
		119	unsigned int base_time;
		120	unsigned int new_time;
		121	// if we are at N-1, stop.
		122	unsigned int next_count = (RPM_Count_Latch + 1) % RPM_SAMPLES;
		123	if (next_count == RPM_Count_Val)
		124	{
		125	break; // completed loop
		126	}
		127	char pulse_level = (RPM_Time[RPM_Count_Latch] & RPM_FLAG) ? 1 : 0;
		128	base_time = RPM_Time[RPM_Count_Latch] & ~RPM_FLAG;
		129	new_time = RPM_Time[next_count] & ~RPM_FLAG;
		130	RPM_Count_Latch = next_count;
		131
		132	uint16_t RPM_Pulsewidth = new_time - base_time;
		133
		134	if (pulse_level == 0 && (RPM_Pulsewidth > ACCUM_MAX))
		135	RPM_State = 1;
		136	if (pulse_level == 1)
		137	RPM_State = 0;
		138
		139	// low pulse has reached at least minimum width, count it.
		140	if ((RPM_State == 1) && (RPM_State_Curr == 0))
		141	{
		142	// Rev counter processing from original RevCounter Project
		143	uint16_t RPM_Diff = new_time - last_dwell_end;
		144
		145	RPM_Period[RPM_Period_Ptr] = RPM_Diff;
		146	RPM_Period_Ptr = (RPM_Period_Ptr + 1) % RPM_AVERAGE;
		147	if (RPM_Pulsecount < RPM_AVERAGE)
		148	RPM_Pulsecount++; // count one pulse
		149	last_dwell_end = new_time;
		150	}
		151	RPM_State_Curr = RPM_State;
		152	}
		153	}
		154
		155	if (RPM_Pulsecount == RPM_AVERAGE)
		156	{
		157	// now have time for N pulses in clocks
		158	// 1Hz is 30 RPM
		159	int i;
		160	unsigned int RPM_FilteredWidth = 0;
		161	for (i = 0; i < RPM_AVERAGE; i++)
		162	RPM_FilteredWidth += RPM_Period[i];
		163
		164	#if !defined MY_DEBUG
		165	// reset here unless we want to debug
		166	RPM_Pulsecount = 0;
		167	#endif
		168	return (Scale * 30.0 * RPM_AVERAGE * RPM_COUNT_RATE) / (RPM_FilteredWidth);
		169	}
		170	else
		171	{
		172	return -1; // flag no reading
		173	}
		174	}
		175	}
		176	#endif // RPMTIMER

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(root)/trunk/src/rpm.cpp – Rev 2