AN 999: Drive-on-Chip with Functional Safety Design Example: Agilex™ 7 Devices

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ID 823627
Date 7/04/2024
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Document Table of Contents
Document Table of Contents x
1. About the Drive-on-Chip with Functional Safety Design Example for Agilex™ 7 Devices 2. Getting Started 3. Rebuilding the Drive-on-Chip Design 4. Functional Description of the Drive-On-Chip with Functional Safety Design Example for Agilex 7 Devices 5. HPS Channel Safety Software 6. Drive-on-Chip Design Recommendations and Disclaimers 7. Document Revision History for AN 999: Drive-on-Chip with Functional Safety Design Example for Agilex 7 Devices
1. About the Drive-on-Chip with Functional Safety Design Example for Agilex™ 7 Devices x
1.1. Features of the Drive-on-Chip with Functional Safety Design Example for Agilex 7 Devices 1.2. About the Safety Concept 1.3. Other Drive-on-Chip Design Documents
1.2. About the Safety Concept x
1.2.1. High-Level Block Diagram of the Drive-On-Chip with Functional Safety Design Example
2. Getting Started x
2.1. Software Requirements for the Drive-On-Chip with Functional Safety Design Example for Agilex 7 Devices 2.2. Hardware Requirements for the Safe Drive-On-Chip with Functional Safety Design Example for Agilex 7 Devices 2.3. Downloading and Installing the Design 2.4. Installing Python 2.5. Creating an SD Card Image 2.6. Setting Up your Development Board for the Drive-On-Chip with Functional Safety Design Example for Agilex 7 Devices 2.7. Debugging and Monitoring the Drive-On-Chip with Functional Safety Design Example for Agilex 7 Devices with Python GUI 2.8. Looking into the Drive-On-Chip Output
2.3. Downloading and Installing the Design x
2.3.1. Design Directory Structure
2.7. Debugging and Monitoring the Drive-On-Chip with Functional Safety Design Example for Agilex 7 Devices with Python GUI x
2.7.1. GUI Safety Function Tab for the Drive-On-Chip with Functional Safety Design Example for Agilex 7 Devices
3. Rebuilding the Drive-on-Chip Design x
3.1. Generating the Platform Designer System 3.2. Generating and Building the NiosV/g BSP for the Drive-On-Chip Design Example 3.3. Compiling the Hardware in the Intel Quartus Prime Software 3.4. Modifying the Motor Control Software Application 3.5. Generating .jic and .rbf files After Hardware Modifications 3.6. Recreate an SD Card Image 3.7. Modifying the HPS Safety Function Application
4. Functional Description of the Drive-On-Chip with Functional Safety Design Example for Agilex 7 Devices x
4.1. Drive-on-Chip Related Subsystems 4.2. HPS Safety Subsystem 4.3. Safety Subsystem 4.4. Shared Memory Subsystem 4.5. External Safety Logic 4.6. Hardware Subsystem 4.7. Voltage Thresholds 4.8. IP Input and Output Signals 4.9. Registers
4.3. Safety Subsystem x
4.3.1. Safety Block 4.3.2. Quadrature Encoder Pulse 4.3.3. Interval Timer
4.3.1. Safety Block x
4.3.1.1. Safety Function Block 4.3.1.2. Cross-Comparison Block
5. HPS Channel Safety Software x
5.1. Meta Layer and Yocto Build 5.2. HPS Channel Speed Monitoring Safety Application
5.1. Meta Layer and Yocto Build x
5.1.1. Layer Configuration Files 5.1.2. Board Support Package Recipes (recipes-bsp)
5.2. HPS Channel Speed Monitoring Safety Application x
5.2.1. Main (hps_safe_channel.c) 5.2.2. Speed Estimation Thread (speed_estmation.c/.h) 5.2.3. Printing Thread (print_safety.c/.h) 5.2.4. Safety Function Application (srt.c/.h) 5.2.5. Access to Devices 5.2.6. Core Isolation and Core Affinity
1. About the Drive-on-Chip with Functional Safety Design Example for Agilex™ 7 Devices
2. Getting Started
3. Rebuilding the Drive-on-Chip Design
4. Functional Description of the Drive-On-Chip with Functional Safety Design Example for Agilex 7 Devices
5. HPS Channel Safety Software
6. Drive-on-Chip Design Recommendations and Disclaimers
7. Document Revision History for AN 999: Drive-on-Chip with Functional Safety Design Example for Agilex 7 Devices

4.3.3. Interval Timer

The interval timer from the Quartus or Platform Designer IP catalog is the source of synchronization of the FPGA channel and the HPS channel. Calculating the speed in both the channels, the cross comparison, and evaluating the safety function must occur in the interval between the timer timeout and interrupt signals.

The interval timer provides the safety response time. In this design, the safety response time is 1 ms. During that time, the FPGA channel generates a payload, writes the payload to shared memory, retrieves the payload from the HPS, and runs the comparison. Similar for the HPS safety channel. The HPS uses the interrupt line from Linux to start the safety function.

In this design, the timer is set to 1 ms interval by writing a count value according by the clock frequency of the timer (in this case 100 MHz). This IP writes to the registers periodl and periodh. Then, the timer runs in free running mode by writing a 0x7 in the control register. When the count reach 0x0, the timer issues an Interrupt for the Linux system (the timer is registered as a UIO device in the Linux DTS with its corresponding interrupt number) and the design assert the timeout output. These signals trigger the safety function in the FPGA and HPS channel respectively. When the interrupt occurs, the systems clears the interrupt and the timeout signal and sets the timer to free running mode again.

For more information about the operation, functions, registers of the interval timer, refer to <project>/hps_software/src/devices/interval_timer.c/.h and the Interval Timer Core User Guide.

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