78 lines
1.9 KiB
Markdown
78 lines
1.9 KiB
Markdown
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- Linux-based
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- Small memory (~20 kB)
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- Wide network stacks
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- TCP/IP
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- IPv6
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- 6LoWPAN
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- IPv6-based
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- Header compression
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- CoAP
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- Application layer protocol
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- RPL
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- Routing for low power
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- Lossy networks
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- SSL/TLS
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- RIME
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- Own communication solution
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- Instant Contiki
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- Dev environment
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- Whole VM
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# Functional
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- Separates basic system from dynamically loadable and programmable services
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- Processes
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- Event-driven kernel
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- Multi-threading supported by library
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- Hybrid OS
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- No hardware abstractions
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- Services communicate by posting kernel events
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- Refer to stack with pointer to process state
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- Each service has state in private memory space
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# Process
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- Cooperative
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- Code running sequentially with respect to other coop code
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- Pre-emptive
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- Temporarily stops cooperative code
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- Normal processes run cooperatively
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- Interrupts and real-time timers run pre-emptively
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- Higher priority
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- Programs are processes
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- Started on boot
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- When module containing process loaded
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- Processes run on timer firing or external events
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# Timers
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- Libraries
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- Used by applications and system
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- Check for timer completion
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- Waking system from low power
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- Real-time task scheduling
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- Allows cooperation when threads sleep
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- Low power mode
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- timer and stimer
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- Simplest
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- See if time period passed
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- Need querying
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- etimer
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- Event timers
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- Scheduling
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- Uses clock time from clock module
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- struct etimer
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## Clock
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- System time starts from zero when the Contiki system starts
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- clock_time()
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- In ticks
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- clock_seconds()
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- In seconds
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- CLOCK_SECOND
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- Ticks per second
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# Power Saving Mode
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- Kernel does not provide any power saving abstractions
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- Need to implement in application
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- To help an application decide when to power down the system
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- The event scheduler exposes the size of event queue
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- If there were not events scheduled, this information can be used to power down the processor
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