Other Parts Discussed in Thread: ADS131M08
Tool/software:
I’m designing a 3-phase energy metering and power quality monitoring system (Class 0.2) with harmonic analysis up to the 31st order for a panel board serving 8 three-phase loads (27 channels total: 24 currents + 3 voltages).
Platform Choice
The MSP430 EMDC ecosystem is attractive for calibration, metering routines, and communication. Among supported MCUs for this library, the MSP430F6779 stands out, but its 16-bit internal ADC isn’t sufficient. Therefore, I’m considering the ADS131M08 (24-bit, 17-bit ENOB @16 ksps) for accurate harmonic analysis. The MSP430 would mainly handle system control, calibration, and comms, while the ADS131M08 handles precision sampling.
Key Challenges
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Channel Count: ADS131M08 has 8 channels, but I need 27 signals. Options: multiplexing (cheaper but risks time skew/accuracy) vs multiple synchronized ADCs (complex/power/data overhead).
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FFT Load: 31st-order harmonic analysis needs 27×512-point FFTs. The MSP430 @25 MHz seems underpowered—likely requiring DSP/FPGA/ARM offload.
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Memory Limits: 27 channels × 512 samples (24-bit) = >40 KB just for buffers, exceeding the MSP430’s 32 KB SRAM. FFTs make this worse. Options: external RAM, multiple MCUs, or streamlined processing.
Question
What’s the most practical architecture for this use case? Should I combine MSP430 + external RAM + ADS131M08, or is it better to offload FFT/memory-heavy tasks to a higher-performance MCU/DSP while keeping MSP430 for control/calibration?
