System Monitor sample

This section provides an example of building and running the System Monitor application within a T2 topology-based repository.

What is the System Monitor

Details of the System Monitor can be found in System Monitor (currently Japanese version only), but it has the following characteristics:

FPGA Watchdog: The system of the SC-OBC Module A1 is monitored by the TRCH (Timing, Reset, Config & Health Controller), and the FPGA reports its internal status to the TRCH via the watchdog signal.

The monitoring by TRCH is disabled by default, so using the FPGA Watchdog feature is not mandatory.

SEM Controller: The SEM (Soft Error Mitigation) Controller is a solution provided by AMD for detecting and correcting errors that occur in the configuration memory of AMD FPGAs. The SC-OBC Module A1 FPGA integrates this functionality into the system and provides access to the SEM Controller’s status through the System Monitor registers.
Board Health Monitor (BHM): The Board Health Monitor (BHM) is a feature that enables easy retrieval of data from sensors mounted on the SC-OBC Module A1. The OBC module is equipped with two current and voltage monitors and three temperature sensors. The BHM allows automatic data acquisition from these sensors without requiring complex I2C operations in software.

System Monitor driver

Currently, the following Zephyr driver APIs are provided for controlling the FPGA’s System Monitor.

Table 1. System Monitor Driver API List
Function	API	Summary	Parameters	Returns
FPGA Watchdog	sc_kick_wdt_timer	Toggle the FPGA Watchdog Timer
SEM Controller	sc_sem_get_error_count	Get the SEM error count		Current SEM error count
Board Health Monitor (BHM)	sc_bhm_enable	Enable the monitoring by BHM NOTE: Currently monitoring interval is fixed at 1 second		0: Success -ETIMEDOUT: Timeout for sensor device initializing
	sc_bhm_disable	Disable the monitoring by BHM		0: Success
	sc_bhm_get_obc_temp	Get the on board temperature sensor value	pos: Position for sensor device <Selectable parameter> SCOBC_A1_TEMP_1 SCOBC_A1_TEMP_2 SCOBC_A1_TEMP_3 temp: Temperature [degree]	0: Success -ENODEV: Wrong parameter -EAGAIN: No updated sensor values
	sc_bhm_get_xadc_temp	Get the FPGA die temperature sensor value	temp: Temperature [degree]	0: Success -EAGAIN: No updated sensor values
	sc_bhm_get_obc_cv	Get the on board Current/Voltage sensor value	pos: Position for sensor device <Selectable parameter> SCOBC_A1_1V0_SHUNT SCOBC_A1_1V0_BUS SCOBC_A1_1V8_SHUNT SCOBC_A1_1V8_BUS SCOBC_A1_3V3_SHUNT SCOBC_A1_3V3_BUS SCOBC_A1_3V3_SYSA_SHUNT SCOBC_A1_3V3_SYSA_BUS SCOBC_A1_3V3_SYSB_SHUNT SCOBC_A1_3V3_SYSB_BUS SCOBC_A1_3V3_IO_SHUNT SCOBC_A1_3V3_IO_BUS cv: Current sensor value [mA] / Voltage sensor value [mV]	0: Success -EAGAIN: No updated sensor values
	sc_bhm_get_xadc_cv	Get the FPGA voltage value	pos: Position for sensor device <Selectable parameter> SCOBC_A1_XADC_VCCINT SCOBC_A1_XADC_VCCAUX SCOBC_A1_XADC_VCCBRAM cv: FPGA Voltage value [mV]	0: Success -EAGAIN: No updated sensor values

These APIs are provided as an out-of-tree driver and are available in System Monitor Driver.

System Monitor sample

The sample application is available in System Monitor sample.

Explain the sample code

Directory name

The directory name and structure for the sample application can be chosen freely. In this example, we use the directory name samples/sysmon.

CMakeLists.txt

A CMakeLists.txt file must be placed directly under the application directory.

# Copyright (c) 2025 Space Cubics Inc.
# SPDX-License-Identifier: Apache-2.0

cmake_minimum_required(VERSION 3.20.0)

find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE})
project(system-monitor)

target_sources(app PRIVATE src/main.c)

Here, the parts that need to be modified for each application are explained.

project: Specify the desired project name
target_sources: Specify the source code file(s)

prj.conf

Additional Kconfig parameters required for running the application can be specified. In this sample, to display temperature data of type float using printf, it is necessary to enable CONFIG_PICOLIBC_IO_FLOAT. For more information about CONFIG_PICOLIBC_IO_FLOAT, refer to CONFIG_PICOLIBC_IO_FLOAT.

CONFIG_PICOLIBC_IO_FLOAT=y

Source code

The source code is shown below. Details will be explained separately.

/*
 * Copyright (c) 2025 Space Cubics Inc.
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#include <zephyr/kernel.h>
#include "sc_sysmon.h"

int main(void)
{
	int ret;
	float temp;
	int32_t bus;

	ret = sc_bhm_enable();
	if (ret < 0) {
		printf("Failed to enable the Board Health Monitor: %d\n", ret);
		goto end;
	}

	/* Wait for the first monitoring to finish */
	k_sleep(K_SECONDS(1));

	while (true) {
		ret = sc_bhm_get_obc_temp(SCOBC_A1_TEMP_1, &temp);
		if (ret < 0) {
			printf("Failed to get the on Board Temperature 1: %d\n", ret);
			goto end;
		}
		printf("On Board Temperature 1 : %.4f [deg]\n", (double)temp);

		ret = sc_bhm_get_obc_cv(SCOBC_A1_3V3_BUS, &bus);
		if (ret < 0) {
			printf("Failed to get the 3V3SYS Bus voltage: %d\n", ret);
			goto end;
		}
		printf("3V3SYS Bus voltage     : %d [mV]\n", bus);

		k_sleep(K_SECONDS(1));
	}

end:
	sc_bhm_disable();

	return ret;
}

Include System Monitor driver header

Include the header file for the System Monitor driver.

#include "sc_sysmon.h"

Enable BHM

Enable the System Monitor by FPGA BHM. If a negative value is returned, sensor initialization has failed.

	ret = sc_bhm_enable();
	if (ret < 0) {
		printf("Failed to enable the Board Health Monitor: %d\n", ret);
		goto end;
	}

Wait 1 second

The current System Monitor driver API does not allow customization of the monitoring interval via BHM; it is fixed at 1 second. Therefore, wait for 1 second until the first data collection is completed.

	k_sleep(K_SECONDS(1));

Get the on board temperature sensor value

Get the temperature data from onboard temperature sensor 1 and display it on the console. If a negative value is returned, it may indicate that the temperature sensor data has not been updated within the FPGA. If you’d like to get other values, try changing the SCOBC_A1_TEMP_1 to a different parameter of your choice, as referenced in Table 1. System Monitor Driver API List

		ret = sc_bhm_get_obc_temp(SCOBC_A1_TEMP_1, &temp);
		if (ret < 0) {
			printf("Failed to get the on Board temperature 1: %d\n", ret);
			goto end;
		}
		printf("On Board Temperature 1 : %.4f [deg]\n", (double)temp);

Get the on board voltage sensor value

Get the 3V3SYS BUS voltage value data from onboard voltage sensor and display it on the console. If a negative value is returned, it may indicate that the voltage sensor data has not been updated within the FPGA. If you’d like to get other values, try changing the SCOBC_A1_3V3_BUS to a different parameter of your choice, as referenced in Table 1. System Monitor Driver API List

		ret = sc_bhm_get_obc_cv(SCOBC_A1_3V3_BUS, &bus);
		if (ret < 0) {
			printf("Failed to get the 3V3SYS Bus voltage: %d\n", ret);
			goto end;
		}
		printf("3V3SYS Bus voltage     : %d [mV]\n", bus);

Open console

Connect the cable between your SC-OBC Module A1 and your PC, then open the console in a terminal:

tio /dev/ttyUSB2

To use the Zephyr console, bit3 (RX) and bit4 (TX) of DIP Switch (SW1) must be turned ON. If they are currently OFF, please switch them ON.

Build

Specify the sample application directory where CMakeLists.txt and prj.conf are placed, and then build as shown below.

cd ~/myproject
source .venv/bin/activate
west build -p always -b scobc_a1 --shield scobc_a1_dev scobc-a1-sample/samples/sysmon

Flash

Next, we’ll flash the SC-OBC Module A1:

west flash

Confirm

Confirm that the temperature from the on board temperature sensor and the 3V3SYS bus voltage are displayed on the console every second.

*** Booting Zephyr OS build 60e8eb54f7ae ***
On Board Temperature 1 : 28.5000 [deg]
3V3SYS Bus voltage     : 3256 [mV]
On Board Temperature 1 : 28.5000 [deg]
3V3SYS Bus voltage     : 3256 [mV]
On Board Temperature 1 : 28.5000 [deg]
3V3SYS Bus voltage     : 3256 [mV]

If you want to exit the tio console, first press Ctrl + t, followed by q.