Hey all :)
My project includes an analogue measure, and in some channels, the input goes over 57000mV in certain, probably random cases.
Of course, it's not a real input because it would fry the MCU. But how can I shield my signal from these spikes, and how do I prevent them totally?
My prj.cfg:
CONFIG_LOG=y CONFIG_I2C=y CONFIG_ADC=y #I know this is only the relevant one, but in case this content is worth something. CONFIG_SFLOAT=y CONFIG_CBPRINTF_FP_SUPPORT=y CONFIG_DK_LIBRARY=y
My devicetree overlay:
/ {
zephyr,user {
io-channels = <&adc 0>, <&adc 1>, <&adc 2>, <&adc 3>;
};
};
&adc {
#address-cells = <1>;
#size-cells = <0>;
channel@0 {
reg = <0>;
zephyr,gain = "ADC_GAIN_1_6";
zephyr,reference = "ADC_REF_INTERNAL";
zephyr,acquisition-time = <ADC_ACQ_TIME_DEFAULT>;
zephyr,input-positive = <NRF_SAADC_AIN0>; /* P0.03 */
zephyr,resolution = <12>;
};
channel@1 {
reg = <1>;
zephyr,gain = "ADC_GAIN_1_6";
zephyr,reference = "ADC_REF_INTERNAL";
zephyr,acquisition-time = <ADC_ACQ_TIME_DEFAULT>;
zephyr,input-positive = <NRF_SAADC_AIN1>;
zephyr,resolution = <12>;
zephyr,oversampling = <8>;
};
channel@2 {
reg = <2>;
zephyr,gain = "ADC_GAIN_1_6";
zephyr,reference = "ADC_REF_INTERNAL";
zephyr,acquisition-time = <ADC_ACQ_TIME_DEFAULT>;
zephyr,input-positive = <NRF_SAADC_AIN2>; /* P0.04 */
zephyr,resolution = <12>;
zephyr,oversampling = <8>;
};
channel@3 {
reg = <3>;
zephyr,gain = "ADC_GAIN_1_6";
zephyr,reference = "ADC_REF_INTERNAL";
zephyr,vref-mv = <750>;
zephyr,acquisition-time = <ADC_ACQ_TIME_DEFAULT>;
zephyr,input-positive = <NRF_SAADC_AIN3>; /* P0.30 */
zephyr,resolution = <12>;
};
};
My main code:
#include <zephyr/device.h>
#include <zephyr/devicetree.h>
#include <zephyr/drivers/adc.h>
#include <zephyr/kernel.h>
#include <zephyr/sys/util.h>
#include <zephyr/logging/log.h>
LOG_MODULE_REGISTER(ADC_Custom_Driver);
#if !DT_NODE_EXISTS(DT_PATH(zephyr_user)) || \
!DT_NODE_HAS_PROP(DT_PATH(zephyr_user), io_channels)
#error "No suitable devicetree overlay specified"
#endif
#define DT_SPEC_AND_COMMA(node_id, prop, idx) \
ADC_DT_SPEC_GET_BY_IDX(node_id, idx),
/* Data of ADC io-channels specified in devicetree. */
static const struct adc_dt_spec adc_channels[] = {
DT_FOREACH_PROP_ELEM(DT_PATH(zephyr_user), io_channels,
DT_SPEC_AND_COMMA)
};
uint16_t buf;
struct adc_sequence sequence = {
.buffer = &buf,
/* buffer size in bytes, not number of samples */
.buffer_size = sizeof(buf),
};
void adc_custom_channels_setup(void)
{ int err;
/* Configure channels individually prior to sampling. */
for (int i = 0U; i < ARRAY_SIZE(adc_channels); i++) {
if (!device_is_ready(adc_channels[i].dev)) {
LOG_WRN("ADC controller device not ready\n");
return;
}
err = adc_channel_setup_dt(&adc_channels[i]);
if (err < 0) {
LOG_ERR("Could not setup channel #%d (%d)\n", i, err);
return;
}
}
}
int adc_custom_measure_channel(uint8_t idx)
{
int err;
uint16_t value;
(void)adc_sequence_init_dt(&adc_channels[idx], &sequence);
err = adc_read(adc_channels[idx].dev, &sequence);
if (err < 0) {
LOG_ERR("Could not read (%d)\n", err);
} else {
//LOG_INF("%"PRId16, buf);
value = (uint16_t)buf;
LOG_DBG("Values.channels[%d] = %d\n", idx, value);
return value;
}
}
int adc_custom_measure_channel_mv(uint8_t idx)
{
int err;
int32_t val_mv;
(void)adc_sequence_init_dt(&adc_channels[idx], &sequence);
err = adc_read(adc_channels[idx].dev, &sequence);
/* conversion to mV may not be supported, skip if not */
val_mv = buf;
err = adc_raw_to_millivolts_dt(&adc_channels[idx],
&val_mv);
if (err < 0 || val_mv > 5000) {
LOG_ERR(" (value in mV not available)\n");
} else {
LOG_DBG("Values_mv[%d] = %d mV\n",idx, val_mv);
return val_mv;
}
}
I call the setup once and in a loop for the measure / measure_print methods.
Is this bug possible because I configured the functions as int and not uint16?
I'm using nRF52840 / Thingy52 (with proper overlays, of course) and NCS v2.2.0
