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LRADC Overview

This page defines module boundaries and platform differences. Configuration examples use T527 and Linux 5.15 as the primary reference, but final properties, paths, and symbols must be confirmed in the active SDK branch.

Source basis​

  • Source guide: Linux LRADC Development Guide
  • Version: 1.4
  • Release date: 2025-10-18

Scope​

Applies to the sunxi-lradc.c driver on Linux 5.10 and later, primarily for resistor-ladder keys.

Capabilities​

  • Low-rate ADC key detection
  • Reference voltage and 6-bit quantization
  • Voltage-boundary calculation for multiple keys
  • Sampling filters, input events, and interrupt statistics

Typical source paths​

bsp/drivers/input/keyboard/
bsp/configs/linux-5.15/*.dtsi
device/config/chips/t527/configs/<BOARD>/linux-5.15/board.dts

Pre-configuration checks​

  1. Confirm controller index, pins, voltage domain, supplies, reset, and interrupt from the schematic.
  2. Confirm the controller label, compatible, clocks/resets, and default state in the final SoC DTSI.
  3. Override only board-specific differences in board.dts; do not copy the full SoC resource block.
  4. Inspect the active driver source for property names, units, and defaults.
  5. Save the before/after DTB, defconfig, and target logs for rollback.

Documents in this category​