Hire by skill

A freelance hardware engineer is a contract specialist hired for a defined piece of product work, but "hardware engineer" spans several disciplines: board and electrical design, firmware, mechanical, optics and sensing, test, and regulatory.

An STM32 firmware developer writes and debugs code for ST's ARM Cortex-M microcontrollers: picking the right family, setting up the clock tree and peripherals, writing HAL, LL or register-level drivers, and getting low-power modes, DMA and bootloaders working on the real board.

A BLE firmware engineer builds the Bluetooth Low Energy side of a device: the GATT services your app talks to, advertising and connection parameters, pairing and bonding, throughput, and the power cost of every radio event.

An RTOS firmware engineer decides how firmware is split into tasks and interrupts, sets priorities, sizes stacks, and proves the timing with measurements instead of hope.

An embedded Linux engineer builds and maintains the operating system image your device runs: the Yocto or Buildroot build, the board support package (bootloader, device tree, kernel drivers), the field update mechanism and the security patching that keeps it shippable.

A CAN bus developer designs and implements how a device talks on a CAN or CAN FD network: identifiers and priorities, bit timing, acceptance filters, error handling and the DBC file that documents every message.

A sensor integration engineer turns a sensor into data you can trust: choosing the part against real range, noise and drift requirements, designing the analog front end and digital interface, calibrating each unit, and validating against a reference instrument.

Hire an FEA or CFD consultant when a simulation can settle a design decision faster or more cheaply than building and testing, and scope the work around that decision: the loads, boundary conditions, material data and how the result will be validated.