feat(nrf52xxx/adc|spi): adjustable resolution, improve SPI

go.mod

@@ -14,6 +14,7 @@ require (
 	github.com/mattn/go-colorable v0.1.13
 	github.com/mattn/go-tty v0.0.4
 	github.com/sigurn/crc16 v0.0.0-20211026045750-20ab5afb07e3
+	github.com/stretchr/testify v1.8.4
 	github.com/tetratelabs/wazero v1.6.0
 	go.bug.st/serial v1.6.0
 	golang.org/x/net v0.26.0
@@ -26,12 +27,14 @@ require (
 require (
 	github.com/chromedp/sysutil v1.0.0 // indirect
 	github.com/creack/goselect v0.1.2 // indirect
+	github.com/davecgh/go-spew v1.1.1 // indirect
 	github.com/gobwas/httphead v0.1.0 // indirect
 	github.com/gobwas/pool v0.2.1 // indirect
 	github.com/gobwas/ws v1.1.0 // indirect
 	github.com/josharian/intern v1.0.0 // indirect
 	github.com/mailru/easyjson v0.7.7 // indirect
 	github.com/mattn/go-isatty v0.0.20 // indirect
-	github.com/stretchr/testify v1.8.4 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
 	golang.org/x/text v0.16.0 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
 )

go.sum

@@ -12,6 +12,7 @@ github.com/chromedp/sysutil v1.0.0/go.mod h1:kgWmDdq8fTzXYcKIBqIYvRRTnYb9aNS9moA
 github.com/creack/goselect v0.1.2 h1:2DNy14+JPjRBgPzAd1thbQp4BSIihxcBf0IXhQXDRa0=
 github.com/creack/goselect v0.1.2/go.mod h1:a/NhLweNvqIYMuxcMOuWY516Cimucms3DglDzQP3hKY=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/gobwas/httphead v0.1.0 h1:exrUm0f4YX0L7EBwZHuCF4GDp8aJfVeBrlLQrs6NqWU=
 github.com/gobwas/httphead v0.1.0/go.mod h1:O/RXo79gxV8G+RqlR/otEwx4Q36zl9rqC5u12GKvMCM=
 github.com/gobwas/pool v0.2.1 h1:xfeeEhW7pwmX8nuLVlqbzVc7udMDrwetjEv+TZIz1og=
@@ -44,6 +45,7 @@ github.com/mattn/go-tty v0.0.4/go.mod h1:u5GGXBtZU6RQoKV8gY5W6UhMudbR5vXnUe7j3px
 github.com/orisano/pixelmatch v0.0.0-20210112091706-4fa4c7ba91d5 h1:1SoBaSPudixRecmlHXb/GxmaD3fLMtHIDN13QujwQuc=
 github.com/orisano/pixelmatch v0.0.0-20210112091706-4fa4c7ba91d5/go.mod h1:nZgzbfBr3hhjoZnS66nKrHmduYNpc34ny7RK4z5/HM0=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/sigurn/crc16 v0.0.0-20211026045750-20ab5afb07e3 h1:aQKxg3+2p+IFXXg97McgDGT5zcMrQoi0EICZs8Pgchs=
 github.com/sigurn/crc16 v0.0.0-20211026045750-20ab5afb07e3/go.mod h1:9/etS5gpQq9BJsJMWg1wpLbfuSnkm8dPF6FdW2JXVhA=
 github.com/stretchr/testify v1.8.4 h1:CcVxjf3Q8PM0mHUKJCdn+eZZtm5yQwehR5yeSVQQcUk=
@@ -74,5 +76,6 @@ gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8
 gopkg.in/yaml.v2 v2.4.0 h1:D8xgwECY7CYvx+Y2n4sBz93Jn9JRvxdiyyo8CTfuKaY=
 gopkg.in/yaml.v2 v2.4.0/go.mod h1:RDklbk79AGWmwhnvt/jBztapEOGDOx6ZbXqjP6csGnQ=
 gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=
 tinygo.org/x/go-llvm v0.0.0-20240627184919-3b50c76783a8 h1:bLsZXRUBavt++CJlMN7sppNziqu3LyamESLhFJcpqFQ=
 tinygo.org/x/go-llvm v0.0.0-20240627184919-3b50c76783a8/go.mod h1:GFbusT2VTA4I+l4j80b17KFK+6whv69Wtny5U+T8RR0=

src/machine/machine_nrf52xxx.go

@@ -8,25 +8,79 @@ import (
 	"unsafe"
 )
 
+const (
+	SPI_MODE_CPHA0_CPOL0 SPIMode = iota
+	SPI_MODE_CPHA1_CPOL0
+	SPI_MODE_CPHA1_CPOL1
+	SPI_MODE_CPHA0_CPOL1
+
+	SPI_MODE_CPHA_FALLING_EDGE_CPOL_ACTIVE_LOW  = SPI_MODE_CPHA0_CPOL0
+	SPI_MODE_CPHA_RISING_EDGE_CPOL_ACTIVE_LOW   = SPI_MODE_CPHA1_CPOL0
+	SPI_MODE_CPHA_RISING_EDGE_CPOL_ACTIVE_HIGH  = SPI_MODE_CPHA1_CPOL1
+	SPI_MODE_CPHA_FALLING_EDGE_CPOL_ACTIVE_HIGH = SPI_MODE_CPHA0_CPOL1
+)
+
+// There are 3 SPI interfaces on the NRF528xx.
+var (
+	SPI0 = SPI{Bus: nrf.SPIM0}
+	SPI1 = SPI{Bus: nrf.SPIM1}
+	SPI2 = SPI{Bus: nrf.SPIM2}
+)
+
+type SPIMode uint8
+
+func (m SPIMode) ApplyTo(conf uint32) uint32 {
+	// See:
+	// - https://de.wikipedia.org/wiki/Serial_Peripheral_Interface#/media/Datei:SPI_timing_diagram2.svg
+	// - https://docs-be.nordicsemi.com/bundle/ps_nrf52840/attach/nRF52840_PS_v1.11.pdf?_LANG=enus page 716, table 43
+	switch m {
+	case SPI_MODE_CPHA0_CPOL0:
+		conf &^= (nrf.SPIM_CONFIG_CPOL_ActiveHigh << nrf.SPIM_CONFIG_CPOL_Pos)
+		conf &^= (nrf.SPIM_CONFIG_CPHA_Leading << nrf.SPIM_CONFIG_CPHA_Pos)
+	case SPI_MODE_CPHA1_CPOL0:
+		conf &^= (nrf.SPIM_CONFIG_CPOL_ActiveHigh << nrf.SPIM_CONFIG_CPOL_Pos)
+		conf |= (nrf.SPIM_CONFIG_CPHA_Trailing << nrf.SPIM_CONFIG_CPHA_Pos)
+	case SPI_MODE_CPHA1_CPOL1:
+		conf |= (nrf.SPIM_CONFIG_CPOL_ActiveLow << nrf.SPIM_CONFIG_CPOL_Pos)
+		conf &^= (nrf.SPIM_CONFIG_CPHA_Leading << nrf.SPIM_CONFIG_CPHA_Pos)
+	case SPI_MODE_CPHA0_CPOL1:
+		conf |= (nrf.SPIM_CONFIG_CPOL_ActiveLow << nrf.SPIM_CONFIG_CPOL_Pos)
+		conf |= (nrf.SPIM_CONFIG_CPHA_Trailing << nrf.SPIM_CONFIG_CPHA_Pos)
+	}
+	return conf
+}
+
 func CPUFrequency() uint32 {
 	return 64000000
 }
 
 // InitADC initializes the registers needed for ADC.
 func InitADC() {
-	return // no specific setup on nrf52 machine.
-}
-
-// Configure configures an ADC pin to be able to read analog data.
-func (a ADC) Configure(config ADCConfig) {
 	// Enable ADC.
-	// The ADC does not consume a noticeable amount of current simply by being
-	// enabled.
+	// The ADC does not consume a noticeable amount of current by being enabled.
 	nrf.SAADC.ENABLE.Set(nrf.SAADC_ENABLE_ENABLE_Enabled << nrf.SAADC_ENABLE_ENABLE_Pos)
+}
 
-	// Use fixed resolution of 12 bits.
-	// TODO: is it useful for users to change this?
-	nrf.SAADC.RESOLUTION.Set(nrf.SAADC_RESOLUTION_VAL_12bit)
+// Configure configures an ADC pin to be able to read analog data.
+// Reference voltage can be 150, 300, 600, 1200, 1800, 2400, 3000(default), 3600 mV
+// Resolution can be 8, 10, 12(default), 14 bits
+// SampleTime will be ceiled to 3(default), 5, 10, 15, 20 or 40(max) µS respectively
+// Samples can be 1(default), 2, 4, 8, 16, 32, 64, 128, 256 samples
+func (a *ADC) Configure(config ADCConfig) {
+	var resolution uint32
+	switch config.Resolution {
+	case 8:
+		resolution = nrf.SAADC_RESOLUTION_VAL_8bit
+	case 10:
+		resolution = nrf.SAADC_RESOLUTION_VAL_10bit
+	case 12:
+		resolution = nrf.SAADC_RESOLUTION_VAL_12bit
+	case 14:
+		resolution = nrf.SAADC_RESOLUTION_VAL_14bit
+	default:
+		resolution = nrf.SAADC_RESOLUTION_VAL_12bit
+	}
+	nrf.SAADC.RESOLUTION.Set(resolution)
 
 	var configVal uint32 = nrf.SAADC_CH_CONFIG_RESP_Bypass<<nrf.SAADC_CH_CONFIG_RESP_Pos |
 		nrf.SAADC_CH_CONFIG_RESP_Bypass<<nrf.SAADC_CH_CONFIG_RESN_Pos |
@@ -51,11 +105,11 @@ func (a ADC) Configure(config ADCConfig) {
 	case 3600: // 3.6V
 		configVal |= nrf.SAADC_CH_CONFIG_GAIN_Gain1_6 << nrf.SAADC_CH_CONFIG_GAIN_Pos
 	default:
-		// TODO: return an error
+		// TODO: return an error, will that interfere with any interfaced if one will be?
 	}
 
-	// Source resistance, according to table 89 on page 364 of the nrf52832 datasheet.
-	// https://infocenter.nordicsemi.com/pdf/nRF52832_PS_v1.4.pdf
+	// Source resistance, according to table 41 on page 676 of the nrf52832 datasheet.
+	// https://docs-be.nordicsemi.com/bundle/ps_nrf52840/attach/nRF52840_PS_v1.11.pdf?_LANG=enus
 	if config.SampleTime <= 3 { // <= 10kΩ
 		configVal |= nrf.SAADC_CH_CONFIG_TACQ_3us << nrf.SAADC_CH_CONFIG_TACQ_Pos
 	} else if config.SampleTime <= 5 { // <= 40kΩ
@@ -103,35 +157,27 @@ func (a ADC) Configure(config ADCConfig) {
 }
 
 // Get returns the current value of a ADC pin in the range 0..0xffff.
-func (a ADC) Get() uint16 {
+func (a *ADC) Get() uint16 {
 	var pwmPin uint32
 	var rawValue volatile.Register16
 
 	switch a.Pin {
 	case 2:
 		pwmPin = nrf.SAADC_CH_PSELP_PSELP_AnalogInput0
-
 	case 3:
 		pwmPin = nrf.SAADC_CH_PSELP_PSELP_AnalogInput1
-
 	case 4:
 		pwmPin = nrf.SAADC_CH_PSELP_PSELP_AnalogInput2
-
 	case 5:
 		pwmPin = nrf.SAADC_CH_PSELP_PSELP_AnalogInput3
-
 	case 28:
 		pwmPin = nrf.SAADC_CH_PSELP_PSELP_AnalogInput4
-
 	case 29:
 		pwmPin = nrf.SAADC_CH_PSELP_PSELP_AnalogInput5
-
 	case 30:
 		pwmPin = nrf.SAADC_CH_PSELP_PSELP_AnalogInput6
-
 	case 31:
 		pwmPin = nrf.SAADC_CH_PSELP_PSELP_AnalogInput7
-
 	default:
 		return 0
 	}
@@ -164,51 +210,34 @@ func (a ADC) Get() uint16 {
 	}
 	nrf.SAADC.EVENTS_STOPPED.Set(0)
 
-	value := int16(rawValue.Get())
-	if value < 0 {
-		value = 0
-	}
-
-	// Return 16-bit result from 12-bit value.
-	return uint16(value << 4)
+	return rawValue.Get()
 }
 
 // SPI on the NRF.
 type SPI struct {
 	Bus *nrf.SPIM_Type
-	buf *[1]byte // 1-byte buffer for the Transfer method
 }
 
-// There are 3 SPI interfaces on the NRF528xx.
-var (
-	SPI0 = SPI{Bus: nrf.SPIM0, buf: new([1]byte)}
-	SPI1 = SPI{Bus: nrf.SPIM1, buf: new([1]byte)}
-	SPI2 = SPI{Bus: nrf.SPIM2, buf: new([1]byte)}
-)
-
 // SPIConfig is used to store config info for SPI.
 type SPIConfig struct {
 	Frequency uint32
 	SCK       Pin
 	SDO       Pin
 	SDI       Pin
 	LSBFirst  bool
-	Mode      uint8
+	Mode      SPIMode
 }
 
 // Configure is intended to setup the SPI interface.
-func (spi SPI) Configure(config SPIConfig) error {
+func (spi *SPI) Configure(config SPIConfig) error {
 	// Disable bus to configure it
 	spi.Bus.ENABLE.Set(nrf.SPIM_ENABLE_ENABLE_Disabled)
 
-	// Pick a default frequency.
-	if config.Frequency == 0 {
-		config.Frequency = 4000000 // 4MHz
-	}
-
 	// set frequency
 	var freq uint32
 	switch {
+	case config.Frequency == 0: // default
+		freq = nrf.SPIM_FREQUENCY_FREQUENCY_M4
 	case config.Frequency >= 8000000:
 		freq = nrf.SPIM_FREQUENCY_FREQUENCY_M8
 	case config.Frequency >= 4000000:
@@ -234,23 +263,7 @@ func (spi SPI) Configure(config SPIConfig) error {
 	}
 
 	// set mode
-	switch config.Mode {
-	case 0:
-		conf &^= (nrf.SPIM_CONFIG_CPOL_ActiveHigh << nrf.SPIM_CONFIG_CPOL_Pos)
-		conf &^= (nrf.SPIM_CONFIG_CPHA_Leading << nrf.SPIM_CONFIG_CPHA_Pos)
-	case 1:
-		conf &^= (nrf.SPIM_CONFIG_CPOL_ActiveHigh << nrf.SPIM_CONFIG_CPOL_Pos)
-		conf |= (nrf.SPIM_CONFIG_CPHA_Trailing << nrf.SPIM_CONFIG_CPHA_Pos)
-	case 2:
-		conf |= (nrf.SPIM_CONFIG_CPOL_ActiveLow << nrf.SPIM_CONFIG_CPOL_Pos)
-		conf &^= (nrf.SPIM_CONFIG_CPHA_Leading << nrf.SPIM_CONFIG_CPHA_Pos)
-	case 3:
-		conf |= (nrf.SPIM_CONFIG_CPOL_ActiveLow << nrf.SPIM_CONFIG_CPOL_Pos)
-		conf |= (nrf.SPIM_CONFIG_CPHA_Trailing << nrf.SPIM_CONFIG_CPHA_Pos)
-	default: // to mode
-		conf &^= (nrf.SPIM_CONFIG_CPOL_ActiveHigh << nrf.SPIM_CONFIG_CPOL_Pos)
-		conf &^= (nrf.SPIM_CONFIG_CPHA_Leading << nrf.SPIM_CONFIG_CPHA_Pos)
-	}
+	conf = config.Mode.ApplyTo(conf)
 	spi.Bus.CONFIG.Set(conf)
 
 	// set pins
@@ -270,10 +283,9 @@ func (spi SPI) Configure(config SPIConfig) error {
 }
 
 // Transfer writes/reads a single byte using the SPI interface.
-func (spi SPI) Transfer(w byte) (byte, error) {
-	buf := spi.buf[:]
-	buf[0] = w
-	err := spi.Tx(buf[:], buf[:])
+func (spi *SPI) Transfer(w byte) (byte, error) {
+	buf := []byte{w}
+	err := spi.Tx(buf, buf)
 	return buf[0], err
 }
 
@@ -282,7 +294,7 @@ func (spi SPI) Transfer(w byte) (byte, error) {
 // as bytes read. Therefore, if the number of bytes don't match it will be
 // padded until they fit: if len(w) > len(r) the extra bytes received will be
 // dropped and if len(w) < len(r) extra 0 bytes will be sent.
-func (spi SPI) Tx(w, r []byte) error {
+func (spi *SPI) Tx(w, r []byte) error {
 	// Unfortunately the hardware (on the nrf52832) only supports up to 255
 	// bytes in the buffers, so if either w or r is longer than that the
 	// transfer needs to be broken up in pieces.
@@ -324,6 +336,16 @@ func (spi SPI) Tx(w, r []byte) error {
 	return nil
 }
 
+// Read implements [io.Reader]. And reads as many bytes as the given buffer is long
+func (spi *SPI) Read(r []byte) (int, error) {
+	return len(r), spi.Tx(nil, r)
+}
+
+// Write implements [io.Writer]. And writes as long as there are bytes in w.
+func (spi *SPI) Write(w []byte) (int, error) {
+	return len(w), spi.Tx(w, nil)
+}
+
 // PWM is one PWM peripheral, which consists of a counter and multiple output
 // channels (that can be connected to actual pins). You can set the frequency
 // using SetPeriod, but only for all the channels in this PWM peripheral at

src/machine/machine_nrf52xxx_test.go

@@ -0,0 +1,69 @@
+//go:build nrf52 || nrf52840 || nrf52833
+
+package machine
+
+import (
+	"github.com/stretchr/testify/require"
+	"testing"
+)
+
+func Test_SPIMode_ApplyTo(t *testing.T) {
+	t.Parallel()
+
+	type args struct {
+		mode   SPIMode
+		config uint32
+	}
+	type want struct {
+		config uint32
+	}
+
+	cases := map[string]struct {
+		args
+		want
+	}{
+		"Mode0": {
+			args: args{
+				mode:   SPI_MODE_CPHA0_CPOL0,
+				config: 0b_11_0,
+			},
+			want: want{
+				config: 0b_00_0,
+			},
+		},
+		"Mode1": {
+			args: args{
+				mode:   SPI_MODE_CPHA1_CPOL0,
+				config: 0b_10_0,
+			},
+			want: want{
+				config: 0b_01_0,
+			},
+		},
+		"Mode2": {
+			args: args{
+				mode:   SPI_MODE_CPHA1_CPOL1,
+				config: 0b_01_0,
+			},
+			want: want{
+				config: 0b_10_0,
+			},
+		},
+		"Mode3": {
+			args: args{
+				mode:   SPI_MODE_CPHA0_CPOL1,
+				config: 0b_00_0,
+			},
+			want: want{
+				config: 0b_11_0,
+			},
+		},
+	}
+
+	for name, tc := range cases {
+		t.Run(name, func(t *testing.T) {
+			actl := tc.args.mode.ApplyTo(tc.args.config)
+			require.Equal(t, tc.want.config, actl)
+		})
+	}
+}