Day33 Log - Minimal IIO Driver

Summary

Implemented a minimal IIO driver using a platform device.

Key features:

• Single voltage channel
• RAW and SCALE attributes
• Direct mode (no buffer)

---

Issues Encountered

1. Unknown symbol error

Cause:

• IIO core module not loaded

Solution:

sudo modprobe industrialio

---

2. No iio:deviceX created

Cause:

• Platform driver had no matching device
• probe() not executed

Solution:

• Created dummy platform device inside module:

platform_device_register_simple("myiio_dummy", ...)

---

Observations

1. sysfs auto-generation

Attributes such as:

in_voltage0_raw
in_voltage0_scale

were automatically created by IIO core.

---

2. read_raw() mapping

Verified:

cat → IIO core → read_raw() → return value

---

3. Channel-driven interface

Changing iio_chan_spec directly affects:

• sysfs attribute names
• available features

---

4. Scale formatting

Using:

IIO_VAL_INT_PLUS_MICRO

produces:

0.001000

---

Key Learning

• IIO uses metadata-driven design
• Device model (probe) is essential
• Framework handles user-space interface

---

Reflection

This minimal driver behaves like:

hwmon-like single-shot sensor

but provides a foundation for:

• multi-channel sampling
• buffered data
• trigger-based acquisition

---