sensor: rm3100: Add ODR build-time setting through DTS property

Using pre-defined values displayed on datasheet's table 5-4 for
CMM Update Rates.

Please note that datasheet specifies these Update-Rates may have
up to 7% standard deviation, which may be significant for certain
applications.

Signed-off-by: Luis Ubieda <[email protected]>

Author: ubieda

drivers/sensor/pni/rm3100/rm3100.c

@@ -12,6 +12,9 @@
 #include <zephyr/rtio/rtio.h>
 #include <zephyr/rtio/work.h>
 #include <zephyr/sys/check.h>
+#include <zephyr/sys/byteorder.h>
+
+#include <zephyr/dt-bindings/sensor/rm3100.h>
 
 #include "rm3100.h"
 #include "rm3100_reg.h"
@@ -130,6 +133,7 @@ static DEVICE_API(sensor, rm3100_driver_api) = {
 
 static int rm3100_init(const struct device *dev)
 {
+	struct rm3100_data *data = dev->data;
 	uint8_t val;
 	int err;
 
@@ -145,6 +149,36 @@ static int rm3100_init(const struct device *dev)
 	}
 	LOG_DBG("RM3100 chip ID confirmed: 0x%02x", val);
 
+	uint16_t cycle_count[] = {
+		sys_be16_to_cpu(RM3100_CYCLE_COUNT_DEFAULT),
+		sys_be16_to_cpu(RM3100_CYCLE_COUNT_DEFAULT),
+		sys_be16_to_cpu(RM3100_CYCLE_COUNT_DEFAULT)
+	};
+
+	/** Setting ODR requires adjusting Cycle-count should it be 600-HZ ODR,
+	 * because at default cycle-count, the max ODR is 440 Hz, which will
+	 * override our setting.
+	 */
+	if (data->settings.odr ==  RM3100_DT_ODR_600) {
+		cycle_count[0] = sys_be16_to_cpu(RM3100_CYCLE_COUNT_HIGH_ODR);
+		cycle_count[1] = sys_be16_to_cpu(RM3100_CYCLE_COUNT_HIGH_ODR);
+		cycle_count[2] = sys_be16_to_cpu(RM3100_CYCLE_COUNT_HIGH_ODR);
+	}
+	 err = rm3100_bus_write(dev, RM3100_REG_CCX_MSB,
+				(uint8_t *)cycle_count, sizeof(cycle_count));
+	if (err < 0) {
+		LOG_ERR("Failed to set cycle count: %d", err);
+		return err;
+	}
+
+	val = data->settings.odr;
+
+	err = rm3100_bus_write(dev, RM3100_REG_TMRC, &val, 1);
+	if (err < 0) {
+		LOG_ERR("Failed to set ODR: %d", err);
+		return err;
+	}
+
 	/** Enable Continuous measurement on all axis */
 	val = RM3100_CMM_ALL_AXIS;
 
@@ -169,6 +203,9 @@ static int rm3100_init(const struct device *dev)
 			.iodev = &rm3100_bus_##inst,						   \
 			.ctx = &rm3100_rtio_ctx_##inst,						   \
 		},										   \
+		.settings = {									   \
+			.odr = DT_INST_PROP(inst, odr),						   \
+		},										   \
 	};											   \
 												   \
 	SENSOR_DEVICE_DT_INST_DEFINE(inst, rm3100_init, NULL,					   \

drivers/sensor/pni/rm3100/rm3100.h

@@ -20,6 +20,7 @@ struct rm3100_encoded_data {
 	struct {
 		uint64_t timestamp;
 		uint8_t channels : 3;
+		uint16_t cycle_count;
 	} header;
 	union {
 		uint8_t payload[RM3100_TOTAL_BYTES];
@@ -41,6 +42,9 @@ struct rm3100_data {
 		struct rtio_iodev *iodev;
 		struct rtio *ctx;
 	} rtio;
+	struct {
+		uint8_t odr;
+	} settings;
 };
 
 #endif /* ZEPHYR_DRIVERS_SENSOR_PNI_RM3100_H_ */

drivers/sensor/pni/rm3100/rm3100_decoder.c

@@ -9,6 +9,7 @@
 #include <zephyr/drivers/sensor_clock.h>
 #include <zephyr/sys/util.h>
 #include <zephyr/sys/byteorder.h>
+#include <zephyr/dt-bindings/sensor/rm3100.h>
 #include "rm3100.h"
 
 uint8_t rm3100_encode_channel(enum sensor_channel chan)
@@ -33,12 +34,19 @@ int rm3100_encode(const struct device *dev,
 		  size_t num_channels,
 		  uint8_t *buf)
 {
+	const struct rm3100_data *data = dev->data;
 	struct rm3100_encoded_data *edata = (struct rm3100_encoded_data *)buf;
 	uint64_t cycles;
 	int err;
 
 	edata->header.channels = 0;
 
+	if (data->settings.odr == RM3100_DT_ODR_600) {
+		edata->header.cycle_count = RM3100_CYCLE_COUNT_HIGH_ODR;
+	} else {
+		edata->header.cycle_count = RM3100_CYCLE_COUNT_DEFAULT;
+	}
+
 	for (size_t i = 0; i < num_channels; i++) {
 		edata->header.channels |= rm3100_encode_channel(channels[i].chan_type);
 	}
@@ -105,19 +113,30 @@ static int rm3100_decoder_get_frame_count(const uint8_t *buffer,
 	return -1;
 }
 
-static int rm3100_convert_raw_to_q31(uint32_t raw_reading, q31_t *out, int8_t *shift)
+static int rm3100_convert_raw_to_q31(uint16_t cycle_count, uint32_t raw_reading,
+				     q31_t *out, int8_t *shift)
 {
 	int64_t value;
+	uint8_t divider;
 
 	raw_reading = sys_be24_to_cpu(raw_reading);
 	value = sign_extend(raw_reading, 23);
 
 	/** Convert to Gauss, assuming 1 LSB = 75 uT, given default Cycle-Counting (200).
 	 * We can represent the largest sample (2^23 LSB) in Gauss with 11 bits.
 	 */
-	*shift = 11;
+	if (cycle_count == RM3100_CYCLE_COUNT_DEFAULT) {
+		*shift = 11;
+		divider = 75;
+	} else {
+		/** Otherwise, it's 1 LSB = 38 uT at Cycle-counting for 600 Hz ODR (100):
+		 * 12-bits max value.
+		 */
+		*shift = 12;
+		divider = 38;
+	}
 
-	int64_t micro_tesla_scaled = ((int64_t)value << (31 - *shift)) / 75;
+	int64_t micro_tesla_scaled = ((int64_t)value << (31 - *shift)) / divider;
 	int64_t gauss_scaled = (int64_t)micro_tesla_scaled / 100;
 
 	*out = gauss_scaled;
@@ -166,7 +185,8 @@ static int rm3100_decoder_decode(const uint8_t *buffer,
 			raw_reading = edata->magn.z;
 		}
 
-		rm3100_convert_raw_to_q31(raw_reading, &out->readings->value, &out->shift);
+		rm3100_convert_raw_to_q31(
+			edata->header.cycle_count, raw_reading, &out->readings->value, &out->shift);
 
 		*fit = 1;
 		return 1;
@@ -182,9 +202,12 @@ static int rm3100_decoder_decode(const uint8_t *buffer,
 		out->header.base_timestamp_ns = edata->header.timestamp;
 		out->header.reading_count = 1;
 
-		rm3100_convert_raw_to_q31(edata->magn.x, &out->readings[0].x, &out->shift);
-		rm3100_convert_raw_to_q31(edata->magn.y, &out->readings[0].y, &out->shift);
-		rm3100_convert_raw_to_q31(edata->magn.z, &out->readings[0].z, &out->shift);
+		rm3100_convert_raw_to_q31(
+			edata->header.cycle_count, edata->magn.x, &out->readings[0].x, &out->shift);
+		rm3100_convert_raw_to_q31(
+			edata->header.cycle_count, edata->magn.y, &out->readings[0].y, &out->shift);
+		rm3100_convert_raw_to_q31(
+			edata->header.cycle_count, edata->magn.z, &out->readings[0].z, &out->shift);
 
 		*fit = 1;
 		return 1;

drivers/sensor/pni/rm3100/rm3100_reg.h

@@ -10,6 +10,13 @@
 
 /* RM3100 register addresses */
 #define RM3100_REG_CMM         0x01 /* Continuous measurement mode */
+#define RM3100_REG_CCX_MSB     0x04 /* Cycle Count X LSB */
+#define RM3100_REG_CCX_LSB     0x05 /* Cycle Count X MSB */
+#define RM3100_REG_CCY_MSB     0x06 /* Cycle Count Y LSB */
+#define RM3100_REG_CCY_LSB     0x07 /* Cycle Count Y MSB */
+#define RM3100_REG_CCZ_MSB     0x08 /* Cycle Count Z LSB */
+#define RM3100_REG_CCZ_LSB     0x09 /* Cycle Count Z MSB */
+#define RM3100_REG_TMRC        0x0B /* Continuous Mode Update Rate */
 #define RM3100_REG_MX          0x24 /* Measurement results X (3 bytes) */
 #define RM3100_REG_MY          0x27 /* Measurement results Y (3 bytes) */
 #define RM3100_REG_MZ          0x2A /* Measurement results Z (3 bytes) */
@@ -21,4 +28,8 @@
 
 #define RM3100_CMM_ALL_AXIS 0x71
 
+#define RM3100_CYCLE_COUNT_DEFAULT 0x00C8	/* Default Cycle Count value */
+#define RM3100_CYCLE_COUNT_HIGH_ODR 0x0064	/* Cycle count value required for 600 Hz ODR */
+
+
 #endif /* ZEPHYR_DRIVERS_SENSOR_PNI_RM3100_REG_H_ */

dts/bindings/sensor/pni,rm3100.yaml

@@ -7,7 +7,43 @@ description: |
 
     The RM3100 can use either I2C or SPI as a communication bus.
     This driver currently supports I2C only.
+    When setting the odr property in a .dts or .dtsi file you may include rm3100.h
+    and use the macros defined there.
+
+    Example:
+    #include <zephyr/dt-bindings/sensor/rm3100.h>
+
+    &i2c0 {
+        rm3100@20 {
+            compatible = "pni,rm3100";
+            reg = <0x20>;
+            odr = <RM3100_DT_ODR_600>;
+        };
+    };
 
 compatible: "pni,rm3100"
 
 include: [sensor-device.yaml, i2c-device.yaml]
+
+properties:
+  odr:
+    type: int
+    default: 0x96
+    description: |
+      The output data rate (ODR) of the sensor in Hz.
+      Default is power-on setting.
+    enum:
+      - 0x92 # RM33100_DT_ODR_600
+      - 0x93 # RM33100_DT_ODR_300
+      - 0x94 # RM33100_DT_ODR_150
+      - 0x95 # RM33100_DT_ODR_75
+      - 0x96 # RM33100_DT_ODR_37_5
+      - 0x97 # RM33100_DT_ODR_18
+      - 0x98 # RM33100_DT_ODR_9
+      - 0x99 # RM33100_DT_ODR_4_5
+      - 0x9A # RM33100_DT_ODR_2_3
+      - 0x9B # RM33100_DT_ODR_1_2
+      - 0x9C # RM33100_DT_ODR_0_6
+      - 0x9D # RM33100_DT_ODR_0_3
+      - 0x9E # RM33100_DT_ODR_0_015
+      - 0x9F # RM33100_DT_ODR_0_0075

include/zephyr/dt-bindings/sensor/rm3100.h

@@ -0,0 +1,39 @@
+/*
+ * Copyright (c) 2024 Intel Corporation
+ * Copyright (c) 2025 Croxel Inc.
+ * Copyright (c) 2025 CogniPilot Foundation
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+#ifndef ZEPHYR_INCLUDE_DT_BINDINGS_PNI_RM3100_H_
+#define ZEPHYR_INCLUDE_DT_BINDINGS_PNI_RM3100_H_
+
+/**
+ * @defgroup RM3100 PNI DT Options
+ * @ingroup sensor_interface
+ * @{
+ */
+
+/**
+ * @defgroup RM3100_ODR Output data rate options
+ * @{
+ */
+#define RM3100_DT_ODR_600	0x92
+#define RM3100_DT_ODR_300	0x93
+#define RM3100_DT_ODR_150	0x94
+#define RM3100_DT_ODR_75	0x95
+#define RM3100_DT_ODR_37_5	0x96
+#define RM3100_DT_ODR_18	0x97
+#define RM3100_DT_ODR_9		0x98
+#define RM3100_DT_ODR_4_5	0x99
+#define RM3100_DT_ODR_2_3	0x9A
+#define RM3100_DT_ODR_1_2	0x9B
+#define RM3100_DT_ODR_0_6	0x9C
+#define RM3100_DT_ODR_0_3	0x9D
+#define RM3100_DT_ODR_0_015	0x9E
+#define RM3100_DT_ODR_0_0075	0x9F
+/** @} */
+
+/** @} */
+
+#endif /* ZEPHYR_INCLUDE_DT_BINDINGS_PNI_RM3100_H_ */