machine/samd21: implement ADC
Signed-off-by: Ron Evans <ron@hybridgroup.com>
Этот коммит содержится в:
Ron Evans
Ayke van Laethem
родитель
5939729c45
коммит
9d6df2b4c7
2 изменённых файлов: 159 добавлений и 0 удалений
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@ -188,6 +188,18 @@ func (p GPIO) Configure(config GPIOConfig) {
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}
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// enable port config
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p.setPinCfg(sam.PORT_PINCFG0_PMUXEN)
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case GPIO_ANALOG:
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if p.Pin&1 > 0 {
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// odd pin, so save the even pins
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val := p.getPMux() & sam.PORT_PMUX0_PMUXE_Msk
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p.setPMux(val | (GPIO_ANALOG << sam.PORT_PMUX0_PMUXO_Pos))
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} else {
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// even pin, so save the odd pins
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val := p.getPMux() & sam.PORT_PMUX0_PMUXO_Msk
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p.setPMux(val | (GPIO_COM << sam.PORT_PMUX0_PMUXE_Pos))
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}
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// enable port config
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p.setPinCfg(sam.PORT_PINCFG0_PMUXEN | sam.PORT_PINCFG0_DRVSTR)
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}
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}
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@ -258,6 +270,141 @@ func (p GPIO) setPinCfg(val sam.RegValue8) {
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setPinCfg(p.Pin, val)
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}
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// InitADC initializes the ADC.
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func InitADC() {
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// ADC Bias Calibration
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// #define ADC_FUSES_BIASCAL_ADDR (NVMCTRL_OTP4 + 4)
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// #define ADC_FUSES_BIASCAL_Pos 3 /**< \brief (NVMCTRL_OTP4) ADC Bias Calibration */
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// #define ADC_FUSES_BIASCAL_Msk (0x7u << ADC_FUSES_BIASCAL_Pos)
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// #define ADC_FUSES_BIASCAL(value) ((ADC_FUSES_BIASCAL_Msk & ((value) << ADC_FUSES_BIASCAL_Pos)))
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// #define ADC_FUSES_LINEARITY_0_ADDR NVMCTRL_OTP4
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// #define ADC_FUSES_LINEARITY_0_Pos 27 /**< \brief (NVMCTRL_OTP4) ADC Linearity bits 4:0 */
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// #define ADC_FUSES_LINEARITY_0_Msk (0x1Fu << ADC_FUSES_LINEARITY_0_Pos)
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// #define ADC_FUSES_LINEARITY_0(value) ((ADC_FUSES_LINEARITY_0_Msk & ((value) << ADC_FUSES_LINEARITY_0_Pos)))
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// #define ADC_FUSES_LINEARITY_1_ADDR (NVMCTRL_OTP4 + 4)
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// #define ADC_FUSES_LINEARITY_1_Pos 0 /**< \brief (NVMCTRL_OTP4) ADC Linearity bits 7:5 */
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// #define ADC_FUSES_LINEARITY_1_Msk (0x7u << ADC_FUSES_LINEARITY_1_Pos)
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// #define ADC_FUSES_LINEARITY_1(value) ((ADC_FUSES_LINEARITY_1_Msk & ((value) << ADC_FUSES_LINEARITY_1_Pos)))
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biasFuse := *(*uint32)(unsafe.Pointer(uintptr(0x00806020) + 4))
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bias := sam.RegValue16(uint16(biasFuse>>3) & uint16(0x7))
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// ADC Linearity bits 4:0
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linearity0Fuse := *(*uint32)(unsafe.Pointer(uintptr(0x00806020)))
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linearity := sam.RegValue16(uint16(linearity0Fuse>>27) & uint16(0x1f))
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// ADC Linearity bits 7:5
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linearity1Fuse := *(*uint32)(unsafe.Pointer(uintptr(0x00806020) + 4))
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linearity |= sam.RegValue16(uint16(linearity1Fuse)&uint16(0x7)) << 5
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// set calibration
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sam.ADC.CALIB = (bias << 8) | linearity
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// Wait for synchronization
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waitADCSync()
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// Divide Clock by 32 with 12 bits resolution as default
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sam.ADC.CTRLB = (sam.ADC_CTRLB_PRESCALER_DIV32 << sam.ADC_CTRLB_PRESCALER_Pos) |
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(sam.ADC_CTRLB_RESSEL_12BIT << sam.ADC_CTRLB_RESSEL_Pos)
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// Sampling Time Length
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sam.ADC.SAMPCTRL = 5
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// Wait for synchronization
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waitADCSync()
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// Use internal ground
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sam.ADC.INPUTCTRL = (sam.ADC_INPUTCTRL_MUXNEG_GND << sam.ADC_INPUTCTRL_MUXNEG_Pos)
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// Averaging (see datasheet table in AVGCTRL register description)
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sam.ADC.AVGCTRL = (sam.ADC_AVGCTRL_SAMPLENUM_1 << sam.ADC_AVGCTRL_SAMPLENUM_Pos) |
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(0x0 << sam.ADC_AVGCTRL_ADJRES_Pos)
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// Analog Reference is AREF pin (3.3v)
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sam.ADC.INPUTCTRL |= (sam.ADC_INPUTCTRL_GAIN_DIV2 << sam.ADC_INPUTCTRL_GAIN_Pos)
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// 1/2 VDDANA = 0.5 * 3V3 = 1.65V
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sam.ADC.REFCTRL |= (sam.ADC_REFCTRL_REFSEL_INTVCC1 << sam.ADC_REFCTRL_REFSEL_Pos)
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}
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// Configure configures a ADCPin to be able to be used to read data.
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func (a ADC) Configure() {
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GPIO{a.Pin}.Configure(GPIOConfig{Mode: GPIO_ANALOG})
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return
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}
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// Get returns the current value of a ADC pin, in the range 0..0xffff.
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func (a ADC) Get() uint16 {
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ch := a.getADCChannel()
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// Selection for the positive ADC input
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sam.ADC.INPUTCTRL &^= sam.ADC_INPUTCTRL_MUXPOS_Msk
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waitADCSync()
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sam.ADC.INPUTCTRL |= sam.RegValue(ch << sam.ADC_INPUTCTRL_MUXPOS_Pos)
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waitADCSync()
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// Enable ADC
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sam.ADC.CTRLA |= sam.ADC_CTRLA_ENABLE
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waitADCSync()
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// Start conversion
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sam.ADC.SWTRIG |= sam.ADC_SWTRIG_START
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waitADCSync()
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// Clear the Data Ready flag
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sam.ADC.INTFLAG = sam.ADC_INTFLAG_RESRDY
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waitADCSync()
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// Start conversion again, since first conversion after reference voltage changed is invalid.
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sam.ADC.SWTRIG |= sam.ADC_SWTRIG_START
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waitADCSync()
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// Waiting for conversion to complete
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for (sam.ADC.INTFLAG & sam.ADC_INTFLAG_RESRDY) == 0 {
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}
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val := sam.ADC.RESULT
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// Disable ADC
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sam.ADC.CTRLA &^= sam.ADC_CTRLA_ENABLE
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waitADCSync()
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return uint16(val)
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}
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func (a ADC) getADCChannel() uint8 {
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switch a.Pin {
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case PA02:
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return 0
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case PB08:
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return 2
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case PB09:
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return 3
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case PA04:
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return 4
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case PA05:
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return 5
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case PA06:
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return 6
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case PA07:
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return 7
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case PB02:
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return 10
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case PB03:
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return 11
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case PA09:
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return 17
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case PA11:
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return 19
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default:
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return 0
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}
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}
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func waitADCSync() {
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for (sam.ADC.STATUS & sam.ADC_STATUS_SYNCBUSY) > 0 {
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}
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}
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// UART on the SAMD21.
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type UART struct {
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Buffer *RingBuffer
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@ -24,6 +24,7 @@ func init() {
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initRTC()
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initSERCOMClocks()
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initUSBClock()
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initADCClock()
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// connect to USB CDC interface
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machine.UART0.Configure(machine.UARTConfig{})
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@ -355,3 +356,14 @@ func initUSBClock() {
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sam.GCLK_CLKCTRL_CLKEN)
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waitForSync()
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}
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func initADCClock() {
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// Turn on clock for ADC
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sam.PM.APBCMASK |= sam.PM_APBCMASK_ADC_
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// Put Generic Clock Generator 0 as source for Generic Clock Multiplexer for ADC.
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sam.GCLK.CLKCTRL = sam.RegValue16((sam.GCLK_CLKCTRL_ID_ADC << sam.GCLK_CLKCTRL_ID_Pos) |
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(sam.GCLK_CLKCTRL_GEN_GCLK0 << sam.GCLK_CLKCTRL_GEN_Pos) |
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sam.GCLK_CLKCTRL_CLKEN)
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waitForSync()
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}
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