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Unformatted text preview: sale as an ASSP (Application Specific Standard Part). It incorporates most of the circuitry required to implement a full-feature ISDN terminal, supporting voice, data and video services down the same digital line. The sort of applications it is targeted at include: ISDN terminal equipment, such as domestic and digital PABX telephones, H.320 videophones and integrated PC communications. 350 Embedded ARM Applications ISDN to DECT (Digital European Cordless Telephone) controllers, allowing a number of cordless telephones to link to each other and to an ISDN line for domestic and business use. ISDN to PCMCIA communication cards. The VIP chip incorporates the specialized interfaces required to connect to the ISDN SO-interface, support for telephony interfaces such as a numeric keypad, a number display, a microphone and an earphone, digital links for external signal processors or codecs, and power management features such as a programmable clock and an analogue to digital converter to monitor the battery state. The ARM6 core performs general control and ISDN protocol functions. A 3 Kbyte on-chip RAM operates without wait states at the full processor clock rate of 36.864 MHz. Critical code routines can be loaded into this RAM as required, for example, the signal processing routines required to support hands-free operation. VIP organization The organization of the VIP chip is illustrated in Figure 13.2 on page 351 and a typical system configuration is shown in Figure 13.3 on page 352. The external memory interface supports 8-, 16- and 32-bit off-chip static RAMs and ROMs and 16- and 32-bit dynamic RAMs. The addressable memory is divided into four ranges, each of which operates with a programmable number of wait states (where the minimum is one wait state giving a 54 ns access time). The on-chip ISDN SO-interface allows connection to an SO-interface bus via isolating transformers and surge protection. The on-chip functions include a phase-locked loop for data and clock recovery, framing, and low-level pr...
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- Spring '09