Method and circuit for interfacing a modem in a wireless communication device to a subscriber interface module
First Claim
1. A circuit for interfacing a modem in a Wireless Communication Device (WCD) to a Subscriber Interface Module (SIM), the SIM including an Input/Output (I/O) port for transmitting and receiving serial data, and a clock input for receiving a SIM clock, comprising:
- a modem controller;
a Universal Asynchronous Receiver/Transmitter (UART) connected to the modem controller, the UART including a transmitter and a receiver to respectively transmit data to and receive data from the SIM I/O port over a common data line; and
a programmable clock circuit adapted to generate the SIM clock and the UART clock based on a common clock provided to the programmable clock circuit, the programmable clock circuit being adapted to generate the SIM clock and the UART clock independently of one another in response to a clock control signal from the modem controller.
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Accused Products
Abstract
A circuit for interfacing a modem in a wireless communication device to a Subscriber Interface Module (SIM) includes a modem controller, a Universal Asynchronous Receiver/Transmitter (UART) connected to the modem controller, a programmable clock circuit adapted to generate a SIM clock and a UART clock independently of one another based on a common clock and a control signal provided to the programmable clock circuit, a reset circuit to generate a SIM reset signal, and a power control circuit to control powering on and off the SIM, all on an integrated circuit chip. The circuit also includes a Bus Interface circuit to interface the modem to the SIM using a common data line.
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Citations
17 Claims
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1. A circuit for interfacing a modem in a Wireless Communication Device (WCD) to a Subscriber Interface Module (SIM), the SIM including an Input/Output (I/O) port for transmitting and receiving serial data, and a clock input for receiving a SIM clock, comprising:
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a modem controller;
a Universal Asynchronous Receiver/Transmitter (UART) connected to the modem controller, the UART including a transmitter and a receiver to respectively transmit data to and receive data from the SIM I/O port over a common data line; and
a programmable clock circuit adapted to generate the SIM clock and the UART clock based on a common clock provided to the programmable clock circuit, the programmable clock circuit being adapted to generate the SIM clock and the UART clock independently of one another in response to a clock control signal from the modem controller. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A circuit on an Integrated Circuit (IC) chip for interfacing a modem in a Wireless Communication Device (WCD) to a Subscriber Interface Module (SIM), the SIM including an Input/Output (I/O) port for transmitting and receiving serial data, a clock input for receiving a SIM clock, and a reset input for receiving a SIM reset signal, comprising:
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a modem controller;
a Universal Asynchronous Receiver/Transmitter (UART) connected to the modem controller, the UART including a transmitter and a receiver to respectively transmit data to and receive data from the SIM I/O port over a common data line; and
a programmable clock circuit adapted to generate the SIM clock and the UART clock based on a common clock provided to the programmable clock circuit, the programmable clock circuit being adapted to generate the SIM clock and the UART clock independently of one another in response to a clock control signal from the modem controller; and
a reset circuit adapted to derive and selectively assert and de-assert the SIM reset signal in response to a SIM reset control signal from the modem controller.
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14. A circuit for interfacing a modem in a Wireless Communication Device (WCD) to a Subscriber Interface Module (SIM), the SIM including an Input/Output (I/O) port for transmitting and receiving serial data, the SIM I/O port having an open-drain configuration, comprising:
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a modem controller;
a Universal Asynchronous Receiver/Transmitter (UART) connected to the modem controller, the UART including a transmitter and a receiver to respectively transmit data to and receive data from the SIM I/O port over a common data line;
a Bus Interface (I/F) circuit having an input coupled to the UART transmitter and an output coupled to the common data line, the Bus I/F circuit being adapted to convert the UART transmitter to an open-drain configuration compatible with the SIM I/O port;
a switch connected between a power supply rail of the WCD and a power supply input of the Bus I/F circuit, the switch being adapted to selectively connect and disconnect the WCD power supply rail to the power input of the Bus I/F circuit in response to a switch control signal; and
a switch control circuit adapted to derive the switch control signal in response to a control signal from the modem controller, whereby the modem controller can selectively apply power to and remove power from the Bus I/F circuit. - View Dependent Claims (15)
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16. A method of interfacing a modem in a Wireless Communication Device (WCD) to a Subscriber Interface Module (SIM), the modem including a modem controller coupled to a Universal Asynchronous Receiver/Transmitter (UART), the UART including a transmitter and a receiver to respectively transmit serial data to and receive serial data from the SIM over a common data line at one or more predetermined baud rates, the UART receiver being configurable to operate in either of a byte mode wherein the UART receiver collects serialized data bytes transmitted thereto at a predetermined baud rate and a sample mode wherein the UART receiver samples a state of the common data line at a sample rate exceeding the predetermined baud rate, comprising the steps of:
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(a) configuring the UART to operate in the sample mode;
(b) transmitting a byte to the SIM over the common line using the UART transmitter;
(c) repetitively sampling a state of the common line during an error signal window occurring after the byte has been transmitted in step (b), thereby collecting sample bytes indicative of whether an error related to the SIM has occurred;
(d) determining whether the error related to the SIM has occurred based on the sample bytes; and
(e) re-transmitting the byte to the SIM when it is determined that the error related to the SIM has occurred. - View Dependent Claims (17)
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Specification