Abstract: The data bus interface apparatus (243) which interfaces between one of a plurality of peripheral units (111) and a data bus (109). The data bus interface driver (243) is capable of biasing data to the voltage level of the data bus (109), accepting data signals (233) having different amplitudes and is immune to differences in ground voltage potentials caused by induced noise and differing environmental conditions. The data bus interface driver (243) is capable of data transition rates in excess of 1 MHz and has low EMI and RFI emissions.

Abstract: The present disclosure includes a discussion of a data transfer system. The data transfer system is responsible for transferring data to and from a radio transceiver (107) and all the corresponding peripheral device ( 111, 113 ) contained in within the radiotelephone (103). The data transfer system includes a data bus (109), a master controller within the transceiver (107) and a peripheral controller within each of the peripheral devices. The data transfer system has an initialization state and a operational state. During the initialization state the data bus (109) operates at a lower frequency than during the operational state. The lower speed increases the time allowed for the assignment of the unique addresses for each of the peripheral controllers. Upon detecting completion of the initialization state, the master controller conducts the change to the operational state.

Abstract: Data transfer apparatus (211,213) for a radiotelephone peripheral using a time multiplexed data bus for communication with a bus master of the radiotelephone couples peripheral devices external to the radiotelephone and other user information inputting devices, such as a handset for a cellular mobile radiotelephone, to the radiotelephone's central processor and speech processor. The data transfer apparatus generates time slots in frame formats in which the information is sent over the data bus. The entire message, information bits and the header, sent in a time slot from a peripheral device to the bus master is used to determine bus contention. Bus contention resolution during the start-up of data bus operation sets the priority with respect to other data transfer apparati with which a peripheral device's data transfer apparatus is able to access the bus during normal operation.

Abstract: A radiotelephone data transfer apparatus connects peripheral devices external to the radiotelephone and other user information inputting devices, such as a handset for a cellular mobile radiotelephone, to the radiotelephone's central processor and speech processor. The data bus apparatus generates frame formats in which the information is sent over the data bus. The frame formats are further subdivided into time slots, the time intervals in which individual messages are sent. The data transfer apparatus is configured so that messages sent to the cellular radiotelephone's speech processor are not flow controlled, while messages sent to the radiotelephone's central processor are flow controlled. Further, the radiotelephone's central processor controls operation of peripheral devices attached to the radiotelephone.