github.com/tinygo-org/tinygo@v0.31.3-0.20240404173401-90b0bf646c27/src/machine/machine_stm32_adc_f4.go (about)

     1  //go:build stm32f4
     2  
     3  package machine
     4  
     5  import (
     6  	"device/stm32"
     7  	"unsafe"
     8  )
     9  
    10  // InitADC initializes the registers needed for ADC1.
    11  func InitADC() {
    12  	// Enable ADC clock
    13  	enableAltFuncClock(unsafe.Pointer(stm32.ADC1))
    14  
    15  	// stop scan, and clear scan resolution
    16  	stm32.ADC1.CR1.ClearBits(stm32.ADC_CR1_SCAN | stm32.ADC_CR1_RES_Msk)
    17  
    18  	// set conversion mode and resolution
    19  	stm32.ADC1.CR1.SetBits(stm32.ADC_CR1_RES_TwelveBit)
    20  
    21  	// clear CONT, ALIGN, EXTEN and EXTSEL bits from CR2
    22  	stm32.ADC1.CR2.ClearBits(stm32.ADC_CR2_CONT | stm32.ADC_CR2_ALIGN | stm32.ADC_CR2_EXTEN_Msk | stm32.ADC_CR2_EXTSEL_Msk)
    23  
    24  	// set CONT, ALIGN, EXTEN and EXTSEL bits from CR2
    25  	stm32.ADC1.CR2.SetBits(stm32.ADC_CR2_CONT_Single | stm32.ADC_CR2_ALIGN_Right)
    26  
    27  	stm32.ADC1.SQR1.ClearBits(stm32.ADC_SQR1_L_Msk)
    28  	stm32.ADC1.SQR1.SetBits(2 << stm32.ADC_SQR1_L_Pos) // 2 means 3 conversions
    29  
    30  	// enable
    31  	stm32.ADC1.CR2.SetBits(stm32.ADC_CR2_ADON)
    32  
    33  	return
    34  }
    35  
    36  // Configure configures an ADC pin to be able to read analog data.
    37  func (a ADC) Configure(ADCConfig) {
    38  	a.Pin.ConfigureAltFunc(PinConfig{Mode: PinInputAnalog}, 0)
    39  
    40  	// set sample time
    41  	ch := a.getChannel()
    42  	if ch > 9 {
    43  		stm32.ADC1.SMPR1.SetBits(stm32.ADC_SMPR1_SMP11_Cycles84 << (ch - 10) * stm32.ADC_SMPR1_SMP11_Pos)
    44  	} else {
    45  		stm32.ADC1.SMPR2.SetBits(stm32.ADC_SMPR2_SMP1_Cycles84 << (ch * stm32.ADC_SMPR2_SMP1_Pos))
    46  	}
    47  
    48  	return
    49  }
    50  
    51  // Get returns the current value of a ADC pin in the range 0..0xffff.
    52  // TODO: DMA based implementation.
    53  func (a ADC) Get() uint16 {
    54  	// set rank
    55  	ch := uint32(a.getChannel())
    56  	stm32.ADC1.SQR3.SetBits(ch)
    57  
    58  	// start conversion
    59  	stm32.ADC1.CR2.SetBits(stm32.ADC_CR2_SWSTART)
    60  
    61  	// wait for conversion to complete
    62  	for !stm32.ADC1.SR.HasBits(stm32.ADC_SR_EOC) {
    63  	}
    64  
    65  	// read 12-bit result as 16 bit value
    66  	result := uint16(stm32.ADC1.DR.Get()) << 4
    67  
    68  	// clear flag
    69  	stm32.ADC1.SR.ClearBits(stm32.ADC_SR_EOC)
    70  
    71  	// clear rank
    72  	stm32.ADC1.SQR3.ClearBits(ch)
    73  
    74  	return result
    75  }
    76  
    77  func (a ADC) getChannel() uint8 {
    78  	switch a.Pin {
    79  	case PA0:
    80  		return 0
    81  	case PA1:
    82  		return 1
    83  	case PA2:
    84  		return 2
    85  	case PA3:
    86  		return 3
    87  	case PA4:
    88  		return 4
    89  	case PA5:
    90  		return 5
    91  	case PA6:
    92  		return 6
    93  	case PA7:
    94  		return 7
    95  	case PB0:
    96  		return 8
    97  	case PB1:
    98  		return 9
    99  	case PC0:
   100  		return 10
   101  	case PC1:
   102  		return 11
   103  	case PC2:
   104  		return 12
   105  	case PC3:
   106  		return 13
   107  	case PC4:
   108  		return 14
   109  	case PC5:
   110  		return 15
   111  	}
   112  
   113  	return 0
   114  }