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Code Issues Packages Projects Releases 6 Wiki Activity

nrf: make ADC resolution changeable (#4701)

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Signed-off-by: Paul Schroeder <milkpirate@users.noreply.github.com>
This commit is contained in:
milkpirate
2025-01-20 21:51:05 +01:00
committed by GitHub
parent 4f39be9c3b
commit 7417c14c2d
1 changed files with 43 additions and 30 deletions
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src/machine/machine_nrf52xxx.go
+43 -30
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@@ -14,20 +14,17 @@ func CPUFrequency() uint32 {
// InitADC initializes the registers needed for ADC.
func InitADC() {
return // no specific setup on nrf52 machine.
// Enable ADC.
// 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)
}
// 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.
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)
// 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 |
nrf.SAADC_CH_CONFIG_REFSEL_Internal<<nrf.SAADC_CH_CONFIG_REFSEL_Pos |
@@ -51,11 +48,26 @@ 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
@@ -102,36 +114,28 @@ 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
}
@@ -164,13 +168,22 @@ func (a ADC) Get() uint16 {
}
nrf.SAADC.EVENTS_STOPPED.Set(0)
value := int16(rawValue.Get())
if value < 0 {
value = 0
// convert to 16 bit resolution/value
var resolutionAdjustment uint8
switch nrf.SAADC.RESOLUTION.Get() {
case nrf.SAADC_RESOLUTION_VAL_8bit:
resolutionAdjustment = 8
case nrf.SAADC_RESOLUTION_VAL_10bit:
resolutionAdjustment = 6
case nrf.SAADC_RESOLUTION_VAL_12bit:
resolutionAdjustment = 4
case nrf.SAADC_RESOLUTION_VAL_14bit:
resolutionAdjustment = 2
default:
resolutionAdjustment = 4 // 12bit
}
// Return 16-bit result from 12-bit value.
return uint16(value << 4)
return rawValue.Get() << resolutionAdjustment
}
// SPI on the NRF.
@@ -196,7 +209,7 @@ 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)