US 6,557,108 B1 · System and method in a modem for providing a shortened reset pulse upon receipt of an external reset pulse

Abstract

A system and method for providing a shortened DSP reset pulse to cause a modem to reset and enter a sleep mode as soon as possible after receipt of an external reset pulse issued by a host. A reset controller detects the external reset pulse, issues a separate reset pulse to the modem, monitors the modem's clock and then terminates the separate reset pulse after a prescribed duration. The prescribed duration is determined by the minimum time required by the DSP to reset. The invention is embodied in a modem connected to an external controller. The modem includes a DSP having a reset terminal and a clock. The DSP begins performing a reset upon a first signal applied to its reset terminal and causes the modem to enter a sleep-mode after a second signal is applied to its reset terminal. The external controller is capable of transmitting an external signal. The reset controller in the modem has a counter and an output node. The counter is connected to the clock and provides a counter output signal upon receipt of a predetermined number of cycles of the clock. The counter initiating generally concurrent with receipt of the external signal. The output node is connected to the reset terminal of the DSP and to the output counter. The output node provides a first signal to the DSP generally concurrent with receipt of the external signal and a second signal generally concurrent with receipt of the counter output signal.

Claims23

Dependent claims

In a modem connected to an external controller, said modem comprising a DSP having a reset terminal and an internal clock, whereby said DSP begins performing a reset upon a first signal applied to said reset terminal and causes said modem to enter a sleep-mode after a second signal is applied to said reset terminal, said external controller being capable of transmitting an external signal, a reset controller in said modem comprising:

a counter connected to said DSP internal clock and providing a counter output signal upon receipt of a predetermined number of cycles of said DSP internal clock, said counter initiating generally concurrent with receipt of the external signal;
and
an output node connected to said reset terminal of said DSP and to said output counter, said output node providing said first signal to said DSP generally concurrent with receipt of the external signal and said second signal generally concurrent with receipt of the counter output signal.

In a modem connected to an external bus, said external bus being controlled by a bus controller, said modem comprising an application circuit connected directly to said external bus, a DSP having a reset terminal and a DSP internal clock whereby said DSP initializes selected registers therein upon a leading edge of a reset pulse applied to said reset terminal and said DSP causes said modem to enter a sleep-mode after the trailing edge of a reset pulse applied to said reset terminal, said DSP and said application circuit connected to said DSP bus, said external bus controller being capable of transmitting on said external bus an external reset pulse of a first duration, a reset controller circuit in said modem comprising:

a counter connected to said DSP internal clock and providing a counter output signal upon receipt of a predetermined number of cycles of said DSP internal clock, said counter initiating generally concurrent with receipt of the leading edge of said external reset pulse;
and
a pulse output node connected to said reset terminal of said DSP and to said output counter, said output node providing a leading DSP reset pulse edge generally concurrent with the leading edge of said external reset pulse and a trailing DSP pulse edge generally concurrent with said counter output signal, so as to provide a reset pulse to said DSP having a duration generally corresponding to said predetermined number of DSP internal clock cycles.

Dependencies are inferred from the claim text.

System and method in a modem for providing a shortened reset pulse upon receipt of an external reset pulse

Life of this patent

System and method in a modem for providing a shortened reset pulse upon receipt of an external reset pulse

Life of this patent

Abstract

Claims23