diff --git a/right/src/buspal/microseconds/microseconds_pit.c b/right/src/buspal/microseconds/microseconds_pit.c index fe31636..3e9fecf 100644 --- a/right/src/buspal/microseconds/microseconds_pit.c +++ b/right/src/buspal/microseconds/microseconds_pit.c @@ -1,43 +1,15 @@ -/* - * @file microseconds.c - * @brief Microseconds timer driver source file - * - * Notes: The driver configure PIT as lifetime timer - */ #include "microseconds/microseconds.h" #include #include "bus_pal_hardware.h" -//////////////////////////////////////////////////////////////////////////////// -// Definitions -//////////////////////////////////////////////////////////////////////////////// - -// Below MACROs are defined in order to keep this driver compabtile among all targets. -#if defined(PIT0) -#define PIT PIT0 -#endif -#if defined(SIM_SCGC6_PIT0_MASK) -#define SIM_SCGC6_PIT_MASK SIM_SCGC6_PIT0_MASK -#endif - -enum -{ +enum { kFrequency_1MHz = 1000000UL }; -//////////////////////////////////////////////////////////////////////////////// -// Variables -//////////////////////////////////////////////////////////////////////////////// -uint32_t s_tickPerMicrosecondMul8; //!< This value equal to 8 times ticks per microseconds +uint32_t s_tickPerMicrosecondMul8; // This value equals to 8 times ticks per microseconds -//////////////////////////////////////////////////////////////////////////////// -// Code -//////////////////////////////////////////////////////////////////////////////// - -//! @brief Initialize timer facilities. -//! -//! It is initialize the timer to lifetime timer by chained channel 0 -//! and channel 1 together, and set b0th channels to maximum counting period +// Initialize the timer to lifetime timer by chained channel 0 and +// channel 1 together, and set both channels to maximum counting period. void microseconds_init(void) { uint32_t busClock; @@ -60,84 +32,65 @@ void microseconds_init(void) PIT->CHANNEL[0].TFLG = 1; // clear the timer 0 flag PIT->CHANNEL[0].TCTRL = PIT_TCTRL_TEN_MASK; // start timer 0 - /* Calculate this value early - * The reason why use this solution is that lowest clock frequency supported by L0PB and L4KS - * is 0.25MHz, this solution will make sure ticks per microscond is greater than 0. - */ + // Calculate this value early + // The reason why use this solution is that lowest clock frequency supported by L0PB and L4KS + // is 0.25MHz, this solution will make sure ticks per microscond is greater than 0. busClock = get_bus_clock(); s_tickPerMicrosecondMul8 = (busClock * 8) / kFrequency_1MHz; // Make sure this value is greater than 0 - if (!s_tickPerMicrosecondMul8) - { + if (!s_tickPerMicrosecondMul8) { s_tickPerMicrosecondMul8 = 1; } } -//! @brief Shutdown the microsecond timer void microseconds_shutdown(void) { - // Turn off PIT: MDIS = 1, FRZ = 0 - PIT->MCR |= PIT_MCR_MDIS_MASK; + PIT->MCR |= PIT_MCR_MDIS_MASK; // Turn off PIT: MDIS = 1, FRZ = 0 } -//! @brief Read back running tick count uint64_t microseconds_get_ticks(void) { uint64_t valueH; uint32_t valueL; -#if defined(FSL_FEATURE_PIT_HAS_LIFETIME_TIMER) && (FSL_FEATURE_PIT_HAS_LIFETIME_TIMER == 1) - valueH = PIT->LTMR64H; - valueL = PIT->LTMR64L; -#else // Make sure that there are no rollover of valueL. // Because the valueL always decreases, so, if the formal valueL is greater than // current value, that means the valueH is updated during read valueL. // In this case, we need to re-update valueH and valueL. - do - { + do { valueH = PIT->CHANNEL[1].CVAL; valueL = PIT->CHANNEL[0].CVAL; } while (valueL < PIT->CHANNEL[0].CVAL); -#endif // FSL_FEATURE_PIT_HAS_LIFETIME_TIMER // Invert to turn into an up counter return ~((valueH << 32) | valueL); } -//! @brief Returns the conversion of ticks to actual microseconds -//! This is used to seperate any calculations from getting a timer -// value for speed critical scenarios +// This is used to seperate any calculations from getting a timer +// value for speed critical scenarios uint32_t microseconds_convert_to_microseconds(uint32_t ticks) { // return the total ticks divided by the number of Mhz the system clock is at to give microseconds - return (8 * ticks / s_tickPerMicrosecondMul8); //!< Assumes system clock will never be < 0.125 Mhz + return (8 * ticks / s_tickPerMicrosecondMul8); // Assumes system clock will never be < 0.125 Mhz } -//! @brief Returns the conversion of microseconds to ticks uint64_t microseconds_convert_to_ticks(uint32_t microseconds) { return ((uint64_t)microseconds * s_tickPerMicrosecondMul8 / 8); } -//! @brief Delay specified time -//! -//! @param us Delay time in microseconds unit void microseconds_delay(uint32_t us) { uint64_t currentTicks = microseconds_get_ticks(); - - //! The clock value in Mhz = ticks/microsecond + // The clock value in Mhz = ticks/microsecond uint64_t ticksNeeded = ((uint64_t)us * s_tickPerMicrosecondMul8 / 8) + currentTicks; - while (microseconds_get_ticks() < ticksNeeded) - { - ; + while (microseconds_get_ticks() < ticksNeeded) { } } -//! @brief Gets the clock value used for microseconds driver +// Get the clock value used for microseconds driver uint32_t microseconds_get_clock(void) { return get_bus_clock();