Device Driver Development: What It Is and Why It Decides Reliability
How embedded device drivers work, where Linux and RTOS drivers differ, common failure modes, and how to test drivers before hardware ships.
A driver is the translation layer between your application and a piece of silicon. When products behave strangely in the field — random resets, missing sensor data, devices that hang overnight — the cause is usually here.
What a driver actually does
- Initialises the peripheral and its clocks, pins and power domains.
- Handles interrupts quickly and defers the slow work.
- Exposes a clean API so the application never touches registers.
- Recovers from bus errors, timeouts and unexpected disconnects.
Linux vs RTOS vs bare metal
Linux kernel modules bring a mature driver model and userspace interfaces but demand strict kernel discipline. RTOS and bare-metal drivers are leaner and more deterministic, and put the whole burden of correctness on you.
Where drivers usually break
- Blocking work inside an interrupt service routine.
- Shared state without protection between ISR and task context.
- No timeout on I2C, SPI or UART transactions.
- Assuming the peripheral always powers up in a known state.
Test before the hardware exists
Abstract the hardware layer so the driver can run against a simulated peripheral, add a logic analyser to the bring-up bench, and script long-running soak tests. Bugs that appear after 40 hours are the ones that reach customers.
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