Project Description
Our largest and most comprehensive project to date. The customer requirement was to build a safety display for a rugged application where high performance, avionics quality LCD readability and convection cooling were some of the design constraints.The display module features a Texas Instruments (TI) Safety CPU handing network traffic from a dual channel CAN network, implementing our own custom safety protocol.
The Safety CPU processes a series of complex polynomial equations and state machines to produce a set of parameters. These parameters are sent to a Xilinx FPGA via a safe PCB level communication channel. The FPGA contains multiple embedded processors and co-processing elements to implement vision processing, graphics processing and user display functions.
Due to the coupling of the Safety CPU and FPGA, the entire PCB was treated as safety critical and all functions meet the architectural and performance requirements for SIL1. The embedded firmware running on the main Safety CPU implements safety related control functions (SRCF’s) per IEC62061 and is designed and tested to SIL1 per IEC61508.
Specific Features:
- Dual 1Mbit CAN (Controller Area Network) Channels. One channel is primary one is for diagnostics. Both channels implement our own proprietary safety protocol meeting the black channel requirements of IEC61508.
- Dual microSD memory card slots (due to high FIT rates for memory)
- Dual DDR3 memories.
- Texas RM4 Safety CPU
- Dual Flash memories
- Quad video camera (surround vision) interface.
- 802.15.4 radio module for external communications
- Monitored power supplies for each group of IC’s.
Safety Parameters:
- Continuous mode, class B, single channel with diagnostics.
- SIL: SIL1 per IEC61508
- PFh: 4.2e-7
- SFF: 0.81
SIL3 Pty. Ltd. designed the schematics and did the initial prototyping for this PCB and outsourced the PCB layout due to time constraints. Read more about it here. After the first samples were manufactured in-house we verified the safety parameters of the PCB via the FMEDA / Fault Injection Testing process.
Do you need a safe display module designed?. Do you have requirements for interfacing and using FPGA’s in Safety Critical Environments?. Contact Us.
