topic Re: AFE Sigma-Delta Channel Mapping and Multi-Phase Input Support on TWR-KM35Z75M (Metering Library) in Kinetis Microcontrollers

AFE Sigma-Delta Channel Mapping and Multi-Phase Input Support on TWR-KM35Z75M (Metering Library)

Anusudhan06 — Thu, 11 Dec 2025 12:02:52 GMT

Hello NXP Team,

I am working on TWR-KM35Z75M using the latest MCUXpresso SDK and evaluating the Metering Library with the MKM35Z512 AFE (24-bit Sigma-Delta ADC). I need clarification on how the AFE channels are configured and how the metering library acquires samples.

SDK: Latest MCUXpresso SDK release for KM35
MCU: MKM35Z512VLQ7 (Kinetis-M series)

1. The metering examples (meterlib1ph_test, meterlib3ph_test) never explicitly reference these pins and need to know exactly where in the SDK the AFE channel-to-signal mapping is configured.
2. Actual AFE sampling rate (Hz / kHz), Whether sampling is triggered internally or by a timer, Whether samples are transferred via DMA, interrupt, or internal FIFO

3. I need to connect three-phase voltage and current signals to the board. What is the recommended channel assignment for 3-phase V/I pairs?

Re: AFE Sigma-Delta Channel Mapping and Multi-Phase Input Support on TWR-KM35Z75M (Metering Library)

carlos_o — Thu, 11 Dec 2025 18:24:26 GMT

Hi @Anusudhan06

Thanks for your post,

There same some Application Notes related to your questions please review it:

Using the FFT on Sigma-Delta ADCs

Kinetis-M Two-Phase Power Meter - Reference Design

Filter-Based Algorithm for Metering Applications

Re: AFE Sigma-Delta Channel Mapping and Multi-Phase Input Support on TWR-KM35Z75M (Metering Library)

Anusudhan06 — Tue, 16 Dec 2025 15:09:07 GMT

Thank you @carlos_o

I am currently integrating the Analog Front-End (AFE) configuration with the Metering Library in my project and would greatly appreciate it if you could provide a reference example.

I have already referred to the provided example file, meteringlib3Ph_test.c, which clearly shows how to use the Metering Library APIs.

However, We would greatly appreciate it, If you could provide a more complete reference example that explicitly demonstrates the integration of both the AFE configuration and the Metering Library together.

Initialization Sequence: The correct order and method for initializing both the AFE and the Metering Library.
Data Flow: How the raw AFE data is captured, formatted, and correctly passed as input to the Metering Library functions.

Thank you for your consideration of this request.

Re: AFE Sigma-Delta Channel Mapping and Multi-Phase Input Support on TWR-KM35Z75M (Metering Library)

Anusudhan06 — Thu, 18 Dec 2025 09:04:31 GMT

I’m circling back to see if you’ve had a chance to look into my request yet.