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UMA1002T Datasheet(PDF) 7 Page - NXP Semiconductors |
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UMA1002T Datasheet(HTML) 7 Page - NXP Semiconductors |
7 / 36 page 1997 Jan 28 7 Philips Semiconductors Product specification Data processor for cellular radio (DPROC2) UMA1002 FUNCTIONAL DESCRIPTION General The UMA1002 (DPROC2) is a single-chip CMOS device which handles the data and supervisory functions of an AMPS or TACS subscriber set. These functions are: • Data reception and transmission • Control and voice channel exchanges • Error detection, correction, decoding and encoding • Supervisory Audio Tone decoding and transponding • Signalling Tone generation. In an AMPS or TACS cellular telephone system, mobile stations communicate with a base over full duplex RF channels. A call is initially set up using one out of a number of dedicated control channels. This establishes a duplex voice connection using a pair of voice channels. Any further transmission of control data occurs on these voice channels by briefly blanking the audio and simultaneously transmitting the data. The data burst is brief and barely noticeable by the user. A data rate of 10 kbits/s is used in the AMPS system and 8 kbits/s in TACS. The signalling formats for both Forward Channels (base to mobile) and Reverse Channels (mobile to base) are shown in Fig.14. A function known as Supervisory Audio Tone (SAT), a set of 3 audio tones (5970, 6000 and 6030 Hz), is used to indicate the presence of the mobile on the designated voice channel. This signal, which is analogous to the On-Hook signal on land lines, is sent out to the mobile by the base station on the Forward Voice Channel. The signal must be accurately recovered and transponded back to the base station to complete the ‘loop’. At the base station this signal is used to ascertain the overall quality of the communication link. Another voice channel associated signal is Signalling Tone (ST). This tone (8 kHz TACS, 10 kHz AMPS) is generated by the mobile and is sent in conjunction with SAT on the Reverse Voice Channel to serve as an acknowledgement signal to a number of system orders. The key requirements of a hand-held portable cellular set are: • Small physical size • Minimum number of interconnections (serial bus) • Low power consumption • Low cost. The DPROC2 is a member of our Cellular Radio chip set, based on the I2C-bus, which meets these requirements. A cellular radio system schematic using the chip set is shown in Fig.11. DPROC2 power-saving features To support current saving in the application, DPROC2 has three different modes of circuit operation implemented. They are decoded by the I2C-bus register bit FVC and by activity on the data transfer link (TXCLK and TXLINE). In power-down mode the relevant digital circuits have the clock disabled, the analog circuits have the bias currents and the switched capacitor clock switched off. • Normal mode: all circuit parts are operating (e.g. on Voice channels) • Power-down mode 1: the SAT path is in power-down (e.g. during access of the RECC) • Power-down mode 2: the SAT path and the total data transmit path are in power-down (e.g. for Idle state, DPROC2 operating only on FOCC). System power-saving features Besides the above mentioned power-down modes DPROC2 also includes features to reduce system current (e.g. switching off parts of the receiver, and put the system controller into Idle mode for longer periods of time). All these features are controlled by the I2C-bus. For further explanation of the following features refer to the Section “I2C-bus serial data link (SDA; SCL)” sub-section “I2C-bus registers”. MAJORITY VOTING (ONLY IN LQFP32) Majority voting includes more intelligence. This feature is enabled in FOCC with I2C-bus bit MAJ = logic 1. If 3 consecutive identical words have been received it is signalled via pin MVO. Therefore during the last 2 frame words the receiver could be switched off to save system current consumption. CONTROL FILLER WORDS FILTER System current can be further reduced by an on-chip control filler words filter in FOCC, which enables the detection of consecutive identical control filler words. If consecutive control filler words are identical (i.e. DCC, CMAC and WFOM) they will not be passed on to the microcontroller. Consequently the system controller can remain in power-saving mode. |
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