Current Sense

Table of Contents

• SDFM
• Features Supported
• Features Not Supported
• ICSS SDFM Design
• Example
• API

Current sensing is handled by the Programmable Real-Time Unit Industrial Communication Subsystem (PRU-ICSS). The PRU-ICSS is a co-processor subsystem containing Programmable Real-Time (PRU) cores which implements the low level firmware. The PRU-ICSS frees up the main ARM cores in the device for other functions, such as control and data processing.

SDFM

ICSS SDFM is a sigma delta interface for phase current measurement in high performance motor and servo drives. During Sigma delta decimation filtering (SDDF) the PRU hardware provides hardware integrators that do the accumulation part of Sinc filtering, while the ICSS SDFM firmware does differentiation part.

Features Supported

• 3 SDFM channels on single PRU core
• Normal current (NC) for data read: SINC3 filter with OSR 16 to 256
• Overcurrent (OC) for comparator: free running SINC3 filter with OSR 16 to 256
• Event generation(ARM interrupt for data read from DMEM, GPIO toggle for high and low thresholds)
• High and Low threshold comparator
• Trigger based normal current sampling
• Double update: Double normal current sampling per EPWM cycle
• SDFM Sync with EPWM

Features Not Supported

• Zero cross comparator
• OSR below 16
• Clock phase compensation
• Fast detect and trip generation

ICSS SDFM Design

SDFM Interface Design explains the design in detail.

Example

SDFM

API

APIs for SDFM