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Unformatted text preview: this class of product is primarily to improve power-efficiency, which it does by reducing the number of off-chip memory accesses. The incorporation of a memory management unit is required to support the class of operating system required to run the general-purpose application mix. The system-on-chip organization is based around the AMBA bus. The peripherals include an LCD controller, serial and parallel I/O ports, an interrupt controller, and a 32-bit external bus interface to give efficient access to off-chip ROM, RAM and DRAM. A DRAM controller provides the necessary multiplexed address and control signals needed by this type of memory. TheARM7100 365 Figure 13.13 ARM7100 organization. Power managemen t The ARM? 100 is intended for use in battery-powered portable equipment where it is expected to deliver high performance in response to user input, but to operate at very low power consumption levels when awaiting user input. To address these requirements the chip has three levels of power management: in full operational mode the ARM CPU delivers around 14 MIPS while consum ing 24mA at 3.0 V; in idle mode with the CPU stopped but other systems running it consumes 33 mW; in standby mode, with only the 32 kHz clock running, it consumes 33 uW. 366 Embedded ARM Applications Other features to enhance power-efficiency include support for self-refresh DRAM memories which will retain their contents with no intervention from the ARM? 100. The Psion Series 5 The organization of the Psion Series 5 is illustrated in Figure 13.14. This shows how the various user interfaces connect to the ARM? 100, giving a system of considerable architectural sophistication with minimal complexity at the chip level. Figure 13.14 The Psion Series 5 hardware organization. The ARM7100 367 The principal user input devices are the keyboard and the stylus pointing device. The former is connected simply to parallel I/O pins; the latter uses a transparent digitizing tablet overlaid on the LCD display and interfaced via an analogue-to-digital...
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This document was uploaded on 10/30/2011 for the course CSE 378 380 at SUNY Buffalo.
- Spring '09