DS18B20示例代码，含search rom的算法的

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Maxim Integrated Products, Inc. retains all * ownership rights. * * $Date: 2017-03-14 17:41:58 -0500 (Tue, 14 Mar 2017) $ * $Revision: 27017 $ * ******************************************************************************/ #include <string.h> #include <stdio.h> #include <stdlib.h> #include "max32625.h" #include "clkman_regs.h" #include "adc_regs.h" #include "pwrseq_regs.h" #include "pwrman_regs.h" #include "icc_regs.h" #include "flc_regs.h" #include "rtc_regs.h" #include "trim_regs.h" #ifndef RO_FREQ #define RO_FREQ 96000000 #endif #ifndef LP0_POST_HOOK #define LP0_POST_HOOK #endif extern void (* const __isr_vector[])(void); uint32_t SystemCoreClock = RO_FREQ/2; void SystemCoreClockUpdate(void) { #ifdef EMULATOR SystemCoreClock = RO_FREQ; #else /* real hardware */ if(MXC_PWRSEQ->reg0 & MXC_F_PWRSEQ_REG0_PWR_RCEN_RUN) { /* 4 MHz source */ if(MXC_PWRSEQ->reg3 & MXC_F_PWRSEQ_REG3_PWR_RC_DIV) { SystemCoreClock = (4000000 / (0x1 << ((MXC_PWRSEQ->reg3 & MXC_F_PWRSEQ_REG3_PWR_RC_DIV) >> MXC_F_PWRSEQ_REG3_PWR_RC_DIV_POS))); } else { SystemCoreClock = 4000000; } } else { /* 96 MHz source */ if(MXC_PWRSEQ->reg3 & MXC_F_PWRSEQ_REG3_PWR_RO_DIV) { SystemCoreClock = (RO_FREQ / (0x1 << ((MXC_PWRSEQ->reg3 & MXC_F_PWRSEQ_REG3_PWR_RO_DIV) >> MXC_F_PWRSEQ_REG3_PWR_RO_DIV_POS))); } else { SystemCoreClock = RO_FREQ; } } #endif } void CLKMAN_TrimRO(void) { uint32_t running; uint32_t trim; /* Step 1: enable 32KHz RTC */ running = MXC_PWRSEQ->reg0 & MXC_F_PWRSEQ_REG0_PWR_RTCEN_RUN; MXC_PWRSEQ->reg0 |= MXC_F_PWRSEQ_REG0_PWR_RTCEN_RUN; /* Wait for RTC warm-up */ while(MXC_RTCCFG->osc_ctrl & MXC_F_RTC_OSC_CTRL_OSC_WARMUP_ENABLE) {} /* Step 2: enable RO calibration complete interrupt */ MXC_ADC->intr |= MXC_F_ADC_INTR_RO_CAL_DONE_IE; /* Step 3: clear RO calibration complete interrupt */ MXC_ADC->intr |= MXC_F_ADC_INTR_RO_CAL_DONE_IF; /* Step 4: -- NO LONGER NEEDED / HANDLED BY STARTUP CODE -- */ /* Step 5: write initial trim to frequency calibration initial condition register */ trim = (MXC_PWRSEQ->reg6 & MXC_F_PWRSEQ_REG6_PWR_TRIM_OSC_VREF) >> MXC_F_PWRSEQ_REG6_PWR_TRIM_OSC_VREF_POS; MXC_ADC->ro_cal1 = (MXC_ADC->ro_cal1 & ~MXC_F_ADC_RO_CAL1_TRM_INIT) | ((trim << MXC_F_ADC_RO_CAL1_TRM_INIT_POS) & MXC_F_ADC_RO_CAL1_TRM_INIT); /* Step 6: load initial trim to active frequency trim register */ MXC_ADC->ro_cal0 |= MXC_F_ADC_RO_CAL0_RO_CAL_LOAD; /* Step 7: enable frequency loop to control RO trim */ MXC_ADC->ro_cal0 |= MXC_F_ADC_RO_CAL0_RO_CAL_EN; /* Step 8: run frequency calibration in atomic mode */ MXC_ADC->ro_cal0 |= MXC_F_ADC_RO_CAL0_RO_CAL_ATOMIC; /* Step 9: waiting for ro_cal_done flag */ while(!(MXC_ADC->intr & MXC_F_ADC_INTR_RO_CAL_DONE_IF)); /* Step 10: stop frequency calibration */ MXC_ADC->ro_cal0 &= ~MXC_F_ADC_RO_CAL0_RO_CAL_RUN; /* Step 11: disable RO calibration complete interrupt */ MXC_ADC->intr &= ~MXC_F_ADC_INTR_RO_CAL_DONE_IE; /* Step 12: read final frequency trim value */ trim = (MXC_ADC->ro_cal0 & MXC_F_ADC_RO_CAL0_RO_TRM) >> MXC_F_ADC_RO_CAL0_RO_TRM_POS; /* Step 13: write final trim to RO flash trim shadow register */ MXC_PWRSEQ->reg6 = (MXC_PWRSEQ->reg6 & ~MXC_F_PWRSEQ_REG6_PWR_TRIM_OSC_VREF) | ((trim << MXC_F_PWRSEQ_REG6_PWR_TRIM_OSC_VREF_POS) & MXC_F_PWRSEQ_REG6_PWR_TRIM_OSC_VREF); /* Step 14: restore RTC status */ if (!running) { MXC_PWRSEQ->reg0 &= ~MXC_F_PWRSEQ_REG0_PWR_RTCEN_RUN; } /* Step 15: disable frequency loop to control RO trim */ MXC_ADC->ro_cal0 &= ~MXC_F_ADC_RO_CAL0_RO_CAL_EN; } static void ICC_Enable(void) { /* Invalidate cache and wait until ready */ MXC_ICC->invdt_all = 1; while (!(MXC_ICC->ctrl_stat & MXC_F_ICC_CTRL_STAT_READY)); /* Enable cache */ MXC_ICC->ctrl_stat |= MXC_F_ICC_CTRL_STAT_ENABLE; /* Must invalidate a second time for proper use */ MXC_ICC->invdt_all = 1; } /* This function is called before C runtime initialization and can be * implemented by the application for early initializations. If a value other * than '0' is returned, the C runtime initialization will be skipped. * * You may over-ride this function in your program by defining a custom * PreInit(), but care should be taken to reproduce the initilization steps * or a non-functional system may result. */ __weak int PreInit(void) { /* Increase system clock to 96 MHz */ MXC_CLKMAN->clk_ctrl = MXC_V_CLKMAN_CLK_CTRL_SYSTEM_SOURCE_SELECT_96MHZ_RO; /* Performance-measurement hook, may be defined as nothing */ LP0_POST_HOOK; /* Enable cache here to reduce boot time */ ICC_Enable(); return 0; } /* This function can be implemented by the application to initialize the board */ __weak int Board_Init(void) { /* Do nothing */ return 0; } /* This function is called just before control is transferred to main(). * * You may over-ride this function in your program by defining a custom * SystemInit(), but care should be taken to reproduce the initialization * steps or a non-functional system may result. */ __weak void SystemInit(void) { /* Configure the interrupt controller to use the application vector table in */ /* the application space */ #if defined ( __GNUC__) /* IAR sets the VTOR pointer prior to SystemInit and causes stack corruption to change it here. */ __disable_irq(); /* Disable interrupts */ SCB->VTOR = (uint32_t)__isr_vector; /* set the Vector Table to point at our ISR table */ __DSB(); /* bus sync */ __enable_irq(); /* enable interrupts */ #endif /* __GNUC__ */ /* Copy trim information from shadow registers into power manager registers */ /* NOTE: Checks have been added to prevent bad/missing trim values from being loaded */ if ((MXC_FLC->ctrl & MXC_F_FLC_CTRL_INFO_BLOCK_VALID) && (MXC_TRIM->for_pwr_reg5 != 0x