diff --git a/libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC81X/us_ticker.c b/libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC81X/us_ticker.c index c1d1a1c10e..b4fb2001e2 100644 --- a/libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC81X/us_ticker.c +++ b/libraries/mbed/targets/hal/TARGET_NXP/TARGET_LPC81X/us_ticker.c @@ -17,77 +17,89 @@ #include "us_ticker_api.h" #include "PeripheralNames.h" -#define US_TICKER_TIMER_IRQn SCT_IRQn +//New, using MRT instead of SCT, needed to free up SCT for PWM +//Ported from LPC824 libs +static int us_ticker_inited = 0; +static int ticker_expired = 0; +int MRT_Clock_MHz; -int us_ticker_inited = 0; +#define US_TICKER_TIMER_IRQn MRT_IRQn void us_ticker_init(void) { - if (us_ticker_inited) return; + + if (us_ticker_inited) + return; + us_ticker_inited = 1; + + // Calculate MRT clock value (MRT has no prescaler) + MRT_Clock_MHz = (SystemCoreClock / 1000000); + + // Enable the MRT clock + LPC_SYSCON->SYSAHBCLKCTRL |= (1 << 10); + + // Clear peripheral reset the MRT + LPC_SYSCON->PRESETCTRL |= (1 << 7); + + // Force load interval value (Bit 0-30 is interval value, Bit 31 is Force Load bit) + LPC_MRT->INTVAL0 = 0xFFFFFFFFUL; + // Enable Ch0 interrupt, Mode 0 is Repeat Interrupt + LPC_MRT->CTRL0 = (0x0 << 1) | (0x1 << 0); + + // Force load interval value (Bit 0-30 is interval value, Bit 31 is Force Load bit) + LPC_MRT->INTVAL1 = 0x80000000UL; + // Disable ch1 interrupt, Mode 0 is Repeat Interrupt + LPC_MRT->CTRL1 = (0x0 << 1) | (0x0 << 0); - // Enable the SCT clock - LPC_SYSCON->SYSAHBCLKCTRL |= (1 << 8); - - // Clear peripheral reset the SCT: - LPC_SYSCON->PRESETCTRL |= (1 << 8); - - // Unified counter (32 bits) - LPC_SCT->CONFIG |= 1; - - // halt and clear the counter - LPC_SCT->CTRL_L |= (1 << 2) | (1 << 3); - - // System Clock (12)MHz -> us_ticker (1)MHz - LPC_SCT->CTRL_L |= ((SystemCoreClock/1000000 - 1) << 5); - - // unhalt the counter: - // - clearing bit 2 of the CTRL register - LPC_SCT->CTRL_L &= ~(1 << 2); - + // Set MRT interrupt vector NVIC_SetVector(US_TICKER_TIMER_IRQn, (uint32_t)us_ticker_irq_handler); NVIC_EnableIRQ(US_TICKER_TIMER_IRQn); } +//TIMER0 is used for us ticker and timers (Timer, wait(), wait_us() etc) uint32_t us_ticker_read() { + if (!us_ticker_inited) us_ticker_init(); - - return LPC_SCT->COUNT_U; + + // Generate ticker value + // MRT source clock is SystemCoreClock (30MHz) and MRT is a 31-bit countdown timer + // Calculate expected value using number of expired times to mimic a 32bit timer @ 1 MHz + return (0x7FFFFFFFUL - LPC_MRT->TIMER0)/MRT_Clock_MHz + (ticker_expired * (0x80000000UL/MRT_Clock_MHz)); } +//TIMER1 is used for Timestamped interrupts (Ticker(), Timeout()) void us_ticker_set_interrupt(timestamp_t timestamp) { - // halt the counter: - // - setting bit 2 of the CTRL register - LPC_SCT->CTRL_L |= (1 << 2); - // set timestamp in compare register - LPC_SCT->MATCH[0].U = (uint32_t)timestamp; + // MRT source clock is SystemCoreClock (30MHz) and MRT is a 31-bit countdown timer + // Force load interval value (Bit 0-30 is interval value, Bit 31 is Force Load bit) + // Note: The MRT has less counter headroom available than the typical mbed 32bit timer @ 1 MHz. + // The calculated counter interval until the next timestamp will be truncated and an + // 'early' interrupt will be generated in case the max required count interval exceeds + // the available 31 bits space. However, the mbed us_ticker interrupt handler will + // check current time against the next scheduled timestamp and simply re-issue the + // same interrupt again when needed. The calculated counter interval will now be smaller. + LPC_MRT->INTVAL1 = (((timestamp - us_ticker_read()) * MRT_Clock_MHz) | 0x80000000UL); - // unhalt the counter: - // - clearing bit 2 of the CTRL register - LPC_SCT->CTRL_L &= ~(1 << 2); + // Enable interrupt + LPC_MRT->CTRL1 |= 1; +} + +//Disable Timestamped interrupts triggered by TIMER1 +void us_ticker_disable_interrupt() { + //Timer1 for Timestamped interrupts (31 bits downcounter @ SystemCoreClock) + LPC_MRT->CTRL1 &= ~1; +} + +void us_ticker_clear_interrupt() { - // if events are not enabled, enable them - if (!(LPC_SCT->EVEN & 0x01)) { - - // comb mode = match only - LPC_SCT->EVENT[0].CTRL = (1 << 12); - - // ref manual: - // In simple applications that do not - // use states, write 0x01 to this - // register to enable an event - LPC_SCT->EVENT[0].STATE |= 0x1; - - // enable events - LPC_SCT->EVEN |= 0x1; + //Timer1 for Timestamped interrupts (31 bits downcounter @ SystemCoreClock) + if (LPC_MRT->STAT1 & 1) + LPC_MRT->STAT1 = 1; + + //Timer0 for us counter (31 bits downcounter @ SystemCoreClock) + if (LPC_MRT->STAT0 & 1) { + LPC_MRT->STAT0 = 1; + ticker_expired++; } } - -void us_ticker_disable_interrupt(void) { - LPC_SCT->EVEN &= ~1; -} - -void us_ticker_clear_interrupt(void) { - LPC_SCT->EVFLAG = 1; -}