2.1.4 Closely coupled peripherals

The subsystem in Cortex®-M3 DesignStart™ Eval provides APB master expansion ports which are used in the example system for UARTs, additional timers, Watchdog, Real Time Clock (RTC), and True Random Number Generator (TRNG).

The remaining five APB master expansion ports can be used for communications interfaces, or other peripherals with a low latency requirement. There are six reserved interrupt lines that are suitable for additional peripherals.

Peripherals can be connected to the APB expansion ports without any modifications to the interconnect within the subsystem. The normal behavior for an unused APB location is to return a read value of 0x00000000, and the expansion ports are fully decoded in the memory map. For more information on the memory map, see the ARM® Cortex®-M3 DesignStart™ Eval RTL and Testbench User Guide.

The TRNG provides a minimum level of functionality that is required to support secure communication. If you require acceleration of encryption functions, then ARM TrustZone® CryptoCell can be licensed separately.

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