Day35 Log - DRDY IRQ Integration

Summary

Extended IIO I2C driver with DRDY GPIO interrupt support.

Achieved:

• STM32-driven data-ready signaling
• Linux GPIO interrupt handling
• verified interrupt flow end-to-end

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Issues Encountered

1. IRQ triggered only once

Cause:

• DRDY not enabled in sensor config

Fix:

CONFIG = ENABLE | DRDY_EN

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2. DRDY edge not re-triggered

Cause:

• signal remained LOW (no new falling edge)

Fix:

• switch to pulse model (LOW → HIGH)

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3. Module reload error

Cannot allocate memory

Cause:

• incorrect working directory / module state

Fix:

• ensure proper unload
• reinsert module correctly

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Observations

1. IRQ flow confirmed

STM32 → GPIO → Linux IRQ → driver

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2. DRDY pulse works

• no IRQ storm
• stable edge trigger

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3. IIO still uses read_raw()

• IRQ does not replace read path yet
• still direct mode

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Key Learning

• Sensor must explicitly enable DRDY behavior
• Edge-triggered IRQ requires proper signal toggling
• Interrupt is a trigger, not data transport
• Proper layering simplifies debugging

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Reflection

This stage bridges:

• firmware signal design (GPIO)
• Linux interrupt handling
• IIO framework integration

It transforms the system from polling-based to event-driven.

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Next Step

Day36:

• implement IIO trigger
• push data to buffer
• enable streaming interface

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