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core: arduino: analogWrite: Fix DAC output calculation #374

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Merged
pennam merged 1 commit into from
Apr 16, 2026
Merged

core: arduino: analogWrite: Fix DAC output calculation #374

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5 changes: 4 additions & 1 deletion cores/arduino/Arduino.h
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Original file line number Diff line number Diff line change
Expand Up @@ -119,7 +119,10 @@ void analogReadResolution(int bits);
#define DAC_ENUMS(n, p, i) DAC##i = i,

enum dacPins {
DT_FOREACH_PROP_ELEM(DT_PATH(zephyr_user), dac_channels, DAC_ENUMS) NUM_OF_DACS
#if DT_PROP_LEN_OR(DT_PATH(zephyr_user), dac_channels, 0) > 0
DT_FOREACH_PROP_ELEM(DT_PATH(zephyr_user), dac_channels, DAC_ENUMS)
#endif
NUM_OF_DACS
};

#endif
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39 changes: 32 additions & 7 deletions cores/arduino/zephyrCommon.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -201,9 +201,13 @@ static const struct device *const dac_dev = DEVICE_DT_GET(DAC_NODE);
.buffered = true, \
},

#if DT_PROP_LEN_OR(DT_PATH(zephyr_user), dac_channels, 0) > 0
static const struct dac_channel_cfg dac_ch_cfg[] = {
DT_FOREACH_PROP_ELEM(DT_PATH(zephyr_user), dac_channels, DAC_CHANNEL_DEFINE)};

static bool dac_channel_initialized[NUM_OF_DACS];
#endif

#endif

#endif // CONFIG_DAC
Expand Down Expand Up @@ -346,18 +350,39 @@ void analogWrite(pin_size_t pinNumber, int value) {

#ifdef CONFIG_DAC
void analogWrite(enum dacPins dacName, int value) {
#if DT_PROP_LEN_OR(DT_PATH(zephyr_user), dac_channels, 0) > 0
const int maxInput = BIT(_analog_write_resolution) - 1U;
int ret = 0;

if (dacName >= NUM_OF_DACS) {
return;
}

// TODO: add reverse map to find pin name from DAC* define
// In the meantime, consider A0 == DAC0
_reinit_peripheral_if_needed((pin_size_t)(dacName + A0), dac_dev);
dac_channel_setup(dac_dev, &dac_ch_cfg[dacName]);
if (!dac_channel_initialized[dacName]) {
if (!device_is_ready(dac_dev)) {
return;
}

const int max_dac_value = 1U << dac_ch_cfg[dacName].resolution;
dac_write_value(dac_dev, dac_ch_cfg[dacName].channel_id,
map(value, 0, 1 << _analog_write_resolution, 0, max_dac_value));
// TODO: add reverse map to find pin name from DAC* define
// In the meantime, consider A0 == DAC0
_reinit_peripheral_if_needed((pin_size_t)(dacName + A0), dac_dev);
ret = dac_channel_setup(dac_dev, &dac_ch_cfg[dacName]);
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if (ret != 0) {
return;
}
dac_channel_initialized[dacName] = true;
}

value = CLAMP(value, 0, maxInput);

const int max_dac_value = BIT(dac_ch_cfg[dacName].resolution) - 1;
const uint32_t output = map(value, 0, maxInput, 0, max_dac_value);

(void)dac_write_value(dac_dev, dac_ch_cfg[dacName].channel_id, output);
#else
ARG_UNUSED(dacName);
ARG_UNUSED(value);
#endif
}
#endif

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