samples: gnss: Add ability to enable RTK

Expand this sample to also work with GNSS_RTK through a serial client.

Make this compatible to work with VMU_RT1170 which requires using the
F9P, instead of the M8 UBX module.

Signed-off-by: Luis Ubieda <luisf@croxel.com>

Author: ubieda

samples/drivers/gnss/README.rst

@@ -26,4 +26,37 @@ Sample Output
     gnss has fix!
     gnss: gnss_satellite: {prn: 1, snr: 30, elevation 71, azimuth 276, system: GLONASS, is_tracked: 1}
     gnss: gnss_satellite: {prn: 11, snr: 31, elevation 62, azimuth 221, system: GLONASS, is_tracked: 1}
-    gnss reported 2 satellites!
+    gnss reported 2 satellites (of which 2 tracked, of which 0 has RTK corrections)!
+
+Real-Time Kinematics (RTK)
+**************************
+
+This sample may also be configured to enable Real-Time Kinematics (RTK) positioning for
+enhanced accuracy, with the assistance of a local base station.
+
+RTK Requirements
+****************
+
+This sample requires the following setup to work with RTK:
+
+* A UBlox F9P GNSS module connected to your board to act as a rover
+* A second UBlox F9P module connected to a PC to act as a base station
+
+Base Station Setup
+******************
+
+To enable RTK functionality:
+
+1. Connect the base station F9P module to your PC via USB.
+2. Also, connect the rover's serial port (running the sample) to your PC via USB.
+3. Note the serial port the rover is connected through (e.g., /dev/ttyUSB0)
+4. Run the base station script:
+
+.. code-block:: console
+
+	python3 base_station/base_station_f9p.py --port /dev/ttyUSB0
+
+The script configures the F9P module as a base station and streams RTCM3
+correction data to the rover. The base station will perform a survey-in
+process to determine its precise position before starting to transmit
+corrections.

samples/drivers/gnss/base_station/base_station_f9p.py

@@ -0,0 +1,83 @@
+# Copyright (c) 2025, Croxel Inc
+# Copyright (c) 2025, CogniPilot Foundation
+#
+# SPDX-License-Identifier: Apache-2.0
+
+import argparse
+
+import pyrtcm
+import pyubx2
+import serial
+
+UBX_F9P_VID = 0x1546
+UBX_F9P_PID = 0x01A9
+
+
+def parse_args():
+    parser = argparse.ArgumentParser(allow_abbrev=False)
+    parser.add_argument(
+        '-p', '--port', required=True, help='Serial Port connected to the Rover (e.g: /dev/ttyUSB0)'
+    )
+
+    return parser.parse_args()
+
+
+def getF9PBaseStationSerialPort():
+    from serial.tools import list_ports
+
+    for port in list_ports.comports():
+        if port.vid == UBX_F9P_VID and port.pid == UBX_F9P_PID:
+            return port.device
+
+    raise RuntimeError(
+        f'Could not find any Serial Port with VID: {hex(UBX_F9P_VID)}, PID: {hex(UBX_F9P_PID)}'
+    )
+
+
+def enableBaseStationMode(serialEndpoint: serial.Serial):
+    frame = pyubx2.UBXMessage.config_set(
+        layers=1,
+        transaction=0,
+        cfgData=[
+            ("CFG_MSGOUT_RTCM_3X_TYPE1005_USB", 1),
+            ("CFG_MSGOUT_RTCM_3X_TYPE1074_USB", 1),
+            ("CFG_MSGOUT_RTCM_3X_TYPE1077_USB", 1),
+            ("CFG_MSGOUT_RTCM_3X_TYPE1084_USB", 1),
+            ("CFG_MSGOUT_RTCM_3X_TYPE1087_USB", 1),
+            ("CFG_MSGOUT_RTCM_3X_TYPE1094_USB", 1),
+            ("CFG_MSGOUT_RTCM_3X_TYPE1097_USB", 1),
+            ("CFG_MSGOUT_RTCM_3X_TYPE1124_USB", 1),
+            ("CFG_MSGOUT_RTCM_3X_TYPE1127_USB", 1),
+            ("CFG_MSGOUT_RTCM_3X_TYPE1230_USB", 1),
+        ],
+    )
+    serialEndpoint.write(frame.serialize())
+
+    frame = pyubx2.UBXMessage.config_set(
+        layers=1,
+        transaction=0,
+        cfgData=[
+            ("CFG_TMODE_MODE", 1),
+            ("CFG_TMODE_SVIN_ACC_LIMIT", 250),
+            ("CFG_TMODE_SVIN_MIN_DUR", 60),
+        ],
+    )
+    serialEndpoint.write(frame.serialize())
+
+
+def main():
+    args = parse_args()
+
+    with (
+        serial.Serial(getF9PBaseStationSerialPort(), 115200) as serialIn,
+        serial.Serial(args.port, 115200) as serialOut,
+    ):
+        enableBaseStationMode(serialIn)
+
+        for raw, parsed in pyrtcm.RTCMReader(serialIn):
+            print(parsed)
+            serialOut.write(raw)
+
+
+if __name__ == '__main__':
+    main()

samples/drivers/gnss/base_station/requirements.txt

@@ -0,0 +1,3 @@
+pyubx2>=1.2.53
+pyrtcm>=1.1.8
+pyserial>=3.5

samples/drivers/gnss/boards/vmu_rt1170_mimxrt1176_cm7.conf

@@ -0,0 +1,7 @@
+# Copyright (c) 2025 Croxel Inc.
+# Copyright (c) 2025 CogniPilot Foundation
+# SPDX-License-Identifier: Apache-2.0
+
+CONFIG_SHELL=n
+CONFIG_SERIAL=y
+CONFIG_UART_INTERRUPT_DRIVEN=y

samples/drivers/gnss/boards/vmu_rt1170_mimxrt1176_cm7.overlay

@@ -8,6 +8,9 @@
 	aliases {
 		gnss = &gnss;
 	};
+	chosen {
+		zephyr,rtk-serial = &lpuart1;
+	};
 };
 
 &lpuart3 {
@@ -16,7 +19,6 @@
 
 	gnss: gnss {
 		status = "okay";
-		compatible = "u-blox,m8";
-		initial-baudrate = <115200>;
+		compatible = "u-blox,f9p";
 	};
 };

samples/drivers/gnss/overlay-rtk.conf

@@ -0,0 +1,6 @@
+# Copyright (c) 2025 Croxel Inc.
+# Copyright (c) 2025 CogniPilot Foundation
+# SPDX-License-Identifier: Apache-2.0
+
+CONFIG_GNSS_RTK=y
+CONFIG_GNSS_RTK_SERIAL=y

samples/drivers/gnss/sample.yaml

@@ -11,3 +11,14 @@ tests:
     filter: dt_alias_exists("gnss")
     integration_platforms:
       - mimxrt1062_fmurt6
+
+  sample.drivers.gnss.rtk:
+    harness: rtk
+    tags:
+      - drivers
+      - gnss
+      - rtk
+    filter: dt_chosen_enabled("zephyr,rtk-serial") and dt_alias_exists("gnss")
+    extra_args: EXTRA_CONF_FILE=overlay-rtk.conf
+    integration_platforms:
+      - vmu_rt1170/mimxrt1176/cm7

samples/drivers/gnss/src/main.c

@@ -11,8 +11,6 @@
 
 #define GNSS_MODEM DEVICE_DT_GET(DT_ALIAS(gnss))
 
-LOG_MODULE_REGISTER(gnss_sample, CONFIG_GNSS_LOG_LEVEL);
-
 static void gnss_data_cb(const struct device *dev, const struct gnss_data *data)
 {
 	uint64_t timepulse_ns;
@@ -21,9 +19,10 @@ static void gnss_data_cb(const struct device *dev, const struct gnss_data *data)
 	if (data->info.fix_status != GNSS_FIX_STATUS_NO_FIX) {
 		if (gnss_get_latest_timepulse(dev, &timepulse) == 0) {
 			timepulse_ns = k_ticks_to_ns_near64(timepulse);
-			printf("Got a fix @ %lld ns\n", timepulse_ns);
+			printf("Got a fix (type: %d) @ %lld ns\n", data->info.fix_status,
+			       timepulse_ns);
 		} else {
-			printf("Got a fix!\n");
+			printf("Got a fix (type: %d)\n", data->info.fix_status);
 		}
 	}
 }
@@ -34,12 +33,14 @@ static void gnss_satellites_cb(const struct device *dev, const struct gnss_satel
 			       uint16_t size)
 {
 	unsigned int tracked_count = 0;
+	unsigned int corrected_count = 0;
 
 	for (unsigned int i = 0; i != size; ++i) {
 		tracked_count += satellites[i].is_tracked;
+		corrected_count += satellites[i].is_corrected;
 	}
-	printf("%u satellite%s reported (of which %u tracked)!\n",
-		size, size > 1 ? "s" : "", tracked_count);
+	printf("%u satellite%s reported (of which %u tracked, of which %u has RTK corrections)!\n",
+	       size, size > 1 ? "s" : "", tracked_count, corrected_count);
 }
 #endif
 GNSS_SATELLITES_CALLBACK_DEFINE(GNSS_MODEM, gnss_satellites_cb);