Safety

Tock takes advantage of hardware-protection mechanisms available on recent microcontrollers and the type-safety features of the Rust programming language to provide a multiprogramming environment that offers isolation of software faults.

Kernel components are isolated at compile-time using Rust’s type and module systems. As a result, sensor drivers, virtualization layers, networking stacks and other components can only access resources they are allowed to, even if they operate on the same bus or share state with other components. For example, two drivers for peripherals on the same I2C bus can only talk to their respective peripherals.

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Reliability

Embedded applications, whether for sensor networks, IoT devices, or security focused, need to be highly reliable. If they crash, there is usually no way for a human to fix them in the field.

The Tock kernel uses an event driven execution model that uses no heap allocation, so the kernel won’t run out of memory. Applications can manage their memory however they want, but are scheduled preemptively and decoupled from the kernel such that the system can keep going if an application crashes or restarts.

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Seamless Low-power

Tock-based systems can run on battery for months or years, or from energy harvesting sources like solar indefinitely. The Tock kernel and drivers seamlessly put the hardware into the lowest possible sleep state based on application requirements. No explicit power-management is required from the application! Even naive apps like this blink app sleep as low as 5μA^*:

int main() {
  while(1) {
    led_toggle(0);
    delay_ms(5000);
  }
}

*As measured on the imix development board. Actual current draw depends on the microcontroller and board.