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//go:build stm32f4
package machine
import (
"device/stm32"
"unsafe"
)
// InitADC initializes the registers needed for ADC1.
func InitADC() {
// Enable ADC clock
enableAltFuncClock(unsafe.Pointer(stm32.ADC1))
// stop scan, and clear scan resolution
stm32.ADC1.CR1.ClearBits(stm32.ADC_CR1_SCAN | stm32.ADC_CR1_RES_Msk)
// set conversion mode and resolution
stm32.ADC1.CR1.SetBits(stm32.ADC_CR1_RES_TwelveBit)
// clear CONT, ALIGN, EXTEN and EXTSEL bits from CR2
stm32.ADC1.CR2.ClearBits(stm32.ADC_CR2_CONT | stm32.ADC_CR2_ALIGN | stm32.ADC_CR2_EXTEN_Msk | stm32.ADC_CR2_EXTSEL_Msk)
// set CONT, ALIGN, EXTEN and EXTSEL bits from CR2
stm32.ADC1.CR2.SetBits(stm32.ADC_CR2_CONT_Single | stm32.ADC_CR2_ALIGN_Right)
stm32.ADC1.SQR1.ClearBits(stm32.ADC_SQR1_L_Msk)
stm32.ADC1.SQR1.SetBits(2 << stm32.ADC_SQR1_L_Pos) // 2 means 3 conversions
// enable
stm32.ADC1.CR2.SetBits(stm32.ADC_CR2_ADON)
return
}
// Configure configures an ADC pin to be able to read analog data.
func (a ADC) Configure(ADCConfig) {
a.Pin.ConfigureAltFunc(PinConfig{Mode: PinInputAnalog}, 0)
// set sample time
ch := a.getChannel()
if ch > 9 {
stm32.ADC1.SMPR1.SetBits(stm32.ADC_SMPR1_SMP11_Cycles84 << (ch - 10) * stm32.ADC_SMPR1_SMP11_Pos)
} else {
stm32.ADC1.SMPR2.SetBits(stm32.ADC_SMPR2_SMP1_Cycles84 << (ch * stm32.ADC_SMPR2_SMP1_Pos))
}
return
}
// Get returns the current value of a ADC pin in the range 0..0xffff.
// TODO: DMA based implementation.
func (a ADC) Get() uint16 {
// set rank
ch := uint32(a.getChannel())
stm32.ADC1.SQR3.SetBits(ch)
// start conversion
stm32.ADC1.CR2.SetBits(stm32.ADC_CR2_SWSTART)
// wait for conversion to complete
for !stm32.ADC1.SR.HasBits(stm32.ADC_SR_EOC) {
}
// read 12-bit result as 16 bit value
result := uint16(stm32.ADC1.DR.Get()) << 4
// clear flag
stm32.ADC1.SR.ClearBits(stm32.ADC_SR_EOC)
// clear rank
stm32.ADC1.SQR3.ClearBits(ch)
return result
}
func (a ADC) getChannel() uint8 {
switch a.Pin {
case PA0:
return 0
case PA1:
return 1
case PA2:
return 2
case PA3:
return 3
case PA4:
return 4
case PA5:
return 5
case PA6:
return 6
case PA7:
return 7
case PB0:
return 8
case PB1:
return 9
case PC0:
return 10
case PC1:
return 11
case PC2:
return 12
case PC3:
return 13
case PC4:
return 14
case PC5:
return 15
}
return 0
}
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