AN 999: Drive-on-Chip with Functional Safety Design Example: Agilex™ 7 Devices
Visible to Intel only — GUID: hrs1716294401440
Ixiasoft
Visible to Intel only — GUID: hrs1716294401440
Ixiasoft
4.3.1.1. Safety Function Block
FUSA and Timer Heartbeat Generator
The heartbeat generator monitors the condition of all the other IPs in the FPGA and HPS channels. The generate bit is a control signal that toggles the heartbeat.
For the FPGA, the generate input is derived from the FPGA Comparison Function state machine's start output, which in turn triggers from the timeout. Therefore, the FPGA heartbeat signal indicates correct restarting controlled by the software and operating comparison function state machine.
Speed Estimator
The speed estimator estimates the speeds of the motor model based off quadrature encoder pulse count. Using this calculated value, the module determines respective safety bits, which pass into the external safety logic. The main algorithm of the estimator is similar to the one in drive on chip, with additional safety diagnostics. The speed estimator module controls local parameters and modifies sampling frequencies.
Payload Generator
The payload generator takes in many different signals from around the overall safety block and generates a payload with all the relevant information. The FPGA-side payload is passed into the cross-comparison block for relevant and respective checks.
Bit range | Length | Data | Description |
---|---|---|---|
[0] | 1 bit | Overspeed indication | 1 for Overspeed |
[25 : 1] | 25 bits | Estimated speed | Measured in rpm |
[31 : 26] | 6 bits | Sequence | Implemented an internal counter to register the sequence of measurements. (0-128) always looping around |