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feat(nrf52xxx/adc|spi): adjustable resolution, improve SPI #4660

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ac8ca36
feat(src/machine/nrf52xxx/adc): move init to init function
milkpirate Jan 14, 2025
10e6124
chore(src/machine/nrf52xxx/adc): fix typo and formatting
milkpirate Jan 14, 2025
bfa1551
feat(src/machine/nrf52xxx/adc): make resolution configurable
milkpirate Jan 14, 2025
de4ef7a
fix(src/machine/nrf52xxx/adc): Register16.Get() already returns uint1…
milkpirate Jan 14, 2025
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61 changes: 30 additions & 31 deletions src/machine/machine_nrf52xxx.go
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Original file line number Diff line number Diff line change
Expand Up @@ -14,19 +14,17 @@ func CPUFrequency() uint32 {

// 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 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 |
Expand All @@ -51,11 +49,26 @@ 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
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)

// 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
Expand Down Expand Up @@ -102,36 +115,28 @@ func (a ADC) Configure(config ADCConfig) {
nrf.SAADC.CH[0].CONFIG.Set(configVal)
}

// Get returns the current value of a ADC pin in the range 0..0xffff.
func (a ADC) Get() uint16 {
// Get returns the current value of an ADC pin in the range 0..0xffff.
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
}
Expand Down Expand Up @@ -164,13 +169,7 @@ 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.
Expand All @@ -196,7 +195,7 @@ type SPIConfig struct {
Mode uint8
}

// Configure is intended to setup the SPI interface.
// Configure is intended to set up the SPI interface.
func (spi SPI) Configure(config SPIConfig) error {
// Disable bus to configure it
spi.Bus.ENABLE.Set(nrf.SPIM_ENABLE_ENABLE_Disabled)
Expand Down
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