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US 5,327,436 AGranted
Communication control system
AssigneeHitachi, Ltd.
InventorTakeshi Miyazaki
Life of this patent
Estimating the term…
Abstract
In a serial communication unit having a CRC calculator or in a single-chip micro-computer including the serial communication unit, the CRC calculator is operated in synchronism with a system clock which is different from and asynchronous with respect to a reception clock. As a result, the CRC calculation is prevented from being stopped by the interruption of the reception clock, or the CRC calculation by the software is unnecessitated, thereby improving the communication efficiency.
Claims31
A serial communication system comprising:
- a modem for supplying serial data and a clock signal synchronous with respect to the serial data;
- a clock generator for providing a system clock signal;
- a synchronization circuit, coupled to receive the clock signal and the system clock signal, for synchronizing the clock signal with the system clock signal to provide a synchronized clock;
- reception means responsive to the synchronized clock and for storing the serial data as received data therein;
- a calculator for calculating an error detect code of the received data;
- latch circuits for storing the received data supplied from the reception means for a desired period of time;
- shift register means in data communication with the latch circuits for converting the data sorted in said latch circuits into serial data and for supplying the serial data to said calculator, wherein said shift register means and said calculator are operated in response to the system clock signal;
- a counter for counting the synchronized clock so as to produce a calculation start signal for said calculator;
- a direct memory access controller which is operated in response to the system clock signal;
- and
- a microprocessor which is operated in response to the system clock signal.
8 more elements
A serial communication system comprising:
- a modem for supplying serial communication data and for supplying a first clock synchronized with the serial communication data;
- a system clock generator for providing a system clock which is synchronous with respect to the first clock;
- synchronization means in data communication with the modem and the system clock generator to receive both the first clock and the system clock and for synchronizing the first clock with the system clock to provide a synchronized clock;
- a reception shift register, in data communication with the modem to receive the serial communication data, for storing the serial communication data in response to the synchronized clock, wherein the first clock supplied from the modem is stopped when the reception shift register stores a last portion of data of the serial communication data therein;
- converting shift register means for converting the data stored in the reception shift register into converted serial data and for supplying the converted serial data, wherein the converting shift register means operates in response to the system clock;
- calculation means in data communication with the converting shift register means to receive the converted serial data supplied from the converting shift register means and for calculating a cyclic redundance check calculation of the converted serial data when receiving a calculation start signal, wherein the calculation means operates in response to the system clock;
- a control circuit in data communication with the synchronization means and the calculation means, the control circuit including counter means for counting the synchronized clock so as to supply the calculation start signal from the control circuit to the calculation means, each time an overflow occurs in the counter means;
- and
- a microprocessor which is in data communication with the system clock and which operates in response to the system clock.
6 more elements
A serial communication system comprising:
- a modem for supplying serial communication data and for supplying a first clock synchronized with the serial communication data;
- a system clock generator for providing a system clock which is synchronous with respect to the first clock;
- synchronization means for synchronizing the first clock with the system clock to provide a synchronized clock;
- a reception shift register coupled to receive the serial communication data for storing the serial communication data in response to the synchronized clock, wherein the first clock supplied from the modem is stopped when the reception shift register stores a last portion of data of the serial communication data therein;
- converting shift register means for converting data stored in the reception shift register into converted serial data and for supplying the converted serial data, wherein the converting shift register means is operated in response to the system clock.
- calculation means coupled to receive the converted serial data and for calculating a cyclic redundance check calculation of the converted serial data when the receiving a calculation start signal, wherein the calculation means is operated in response to the system clock;
- a microprocessor which is operated in response to the system clock;
- a command register for storing a cyclic redundancy check calculation execute command supplied from the microprocessor;
- a command decoder for decoding the cyclic redundancy check calculation execute command stored in the command register to provide the calculation start signal to the calculator.
6 more elements
Dependencies are inferred from the claim text.