Method and control system for the synchronized transmission of digital data
First Claim
1. A method of transmitting digital data in a system including a transmitting unit and a receiving unit that includes a data acceptance clock signal generator having a controllable clock frequency, said method comprising the steps:
- (a) transmitting from said transmitting unit a synchronization pulse train including at least one synchronization pulse and containing a synchronizing time point and a clock frequency information;
(b) after said step (a), transmitting from said transmitting unit a data signal including said digital data;
(c) after said step (a), receiving said synchronization pulse train and ascertaining said clock frequency information from said synchronization pulse train in said receiving unit, wherein said step of ascertaining said clock frequency information comprises determining a respective pulse duration of said at least one synchronization pulse and deriving said clock frequency information from said pulse duration;
(d) after said step (c), synchronizing said data acceptance clock signal generator with said synchronizing time point and controlling said controllable clock frequency of said data acceptance clock signal generator so as to generate therewith a data acceptance clock signal having a clock frequency that is adapted in accordance with said ascertained clock frequency information; and
(e) receiving said data signal in accordance with said data acceptance clock signal in said receiving unit;
wherein said data signal includes at least one data pulse in a data word, said at least one synchronization pulse and said at least one data pulse are respectively pulse width modulated, said clock frequency information contains information indicating a duration of said data word, and said data word and said synchronization pulse train respectively include a first portion having a prescribed first signal level existing for at least a first fixed signal level duration and a second portion having a prescribed second signal level opposite said first signal level existing for at least a second fixed signal level duration, wherein said first portion and said second portion together define a pulse frame width, and further comprising the following steps;
(f) forming a plurality of Pulse frames of said data acceptance clock signal respectively having said pulse frame width, from said information indicating a length of said data word contained in said clock frequency information; and
(g) carrying out said step (e) so as to receive said data word during a respective one of said pulse frames, wherein said data word contains said data in said first portion having said prescribed first signal level within and at a beginning of said respective pulse frame, and said second portion of said data word having said prescribed second signal level occurs at an end of said respective pulse frame, such that a signal level transition occurs at a transition from said end of said respective pulse frame to a beginning of a next successive one of said pulse frames.
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Abstract
In a method and system for transmitting digital data, a data acceptance clock signal generator that has a controllable clock frequency in a peripheral module is correspondingly adapted to clock frequency information derived from a synchronization pulse train transmitted by a central unit. The same oscillator is used as a frequency source for determining the clock frequency information and for generating the data acceptance clock pulse. In this manner, simple RC oscillators are adequate to fulfill any requirements of long time accuracy of the oscillator. The clock frequency can be changed in that the central unit simply transmits altered clock frequency information. It is also possible to carry out an adjustment or adaptation in the case of deviations of the oscillator frequency in the peripheral unit. Preferably, the clock frequency information is derived from the reciprocal value of the time duration of at least one synchronization pulse, which is determined in a quantized manner by a first counter in a clock frequency information acquisition circuit which counts the number of oscillator pulses occurring during the synchronization pulse. The resulting count value is provided to a data acceptance clock signal generator, which is clocked by the same oscillator and counts the number of oscillator pulses until reaching a prescribed threshold value, whereupon it outputs a corresponding clock signal. By properly adapting numerical elements, it is also possible to process pulse width modulated signals using the present method and apparatus.
76 Citations
35 Claims
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1. A method of transmitting digital data in a system including a transmitting unit and a receiving unit that includes a data acceptance clock signal generator having a controllable clock frequency, said method comprising the steps:
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(a) transmitting from said transmitting unit a synchronization pulse train including at least one synchronization pulse and containing a synchronizing time point and a clock frequency information; (b) after said step (a), transmitting from said transmitting unit a data signal including said digital data; (c) after said step (a), receiving said synchronization pulse train and ascertaining said clock frequency information from said synchronization pulse train in said receiving unit, wherein said step of ascertaining said clock frequency information comprises determining a respective pulse duration of said at least one synchronization pulse and deriving said clock frequency information from said pulse duration; (d) after said step (c), synchronizing said data acceptance clock signal generator with said synchronizing time point and controlling said controllable clock frequency of said data acceptance clock signal generator so as to generate therewith a data acceptance clock signal having a clock frequency that is adapted in accordance with said ascertained clock frequency information; and (e) receiving said data signal in accordance with said data acceptance clock signal in said receiving unit; wherein said data signal includes at least one data pulse in a data word, said at least one synchronization pulse and said at least one data pulse are respectively pulse width modulated, said clock frequency information contains information indicating a duration of said data word, and said data word and said synchronization pulse train respectively include a first portion having a prescribed first signal level existing for at least a first fixed signal level duration and a second portion having a prescribed second signal level opposite said first signal level existing for at least a second fixed signal level duration, wherein said first portion and said second portion together define a pulse frame width, and further comprising the following steps; (f) forming a plurality of Pulse frames of said data acceptance clock signal respectively having said pulse frame width, from said information indicating a length of said data word contained in said clock frequency information; and (g) carrying out said step (e) so as to receive said data word during a respective one of said pulse frames, wherein said data word contains said data in said first portion having said prescribed first signal level within and at a beginning of said respective pulse frame, and said second portion of said data word having said prescribed second signal level occurs at an end of said respective pulse frame, such that a signal level transition occurs at a transition from said end of said respective pulse frame to a beginning of a next successive one of said pulse frames. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A method of transmitting digital data in a system including a transmitting unit and a receiving unit that includes a data acceptance clock signal generator having a controllable clock frequency, said method comprising the steps:
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(a) transmitting from said transmitting unit a synchronization pulse train including at least one synchronization pulse and containing a synchronizing time point and a clock frequency information; (b) after said step (a), transmitting from said transmitting unit a data signal including said digital data; (c) after said step (a), receiving said synchronization pulse train and ascertaining said clock frequency information from said synchronization pulse train in said receiving unit, wherein said step of ascertaining said clock frequency information comprises determining a respective pulse duration of said at least one synchronization pulse and deriving said clock frequency information from said pulse duration; (d) after said step (c), synchronizing said data acceptance clock signal generator with said synchronizing time point and controlling said controllable clock frequency of said data acceptance clock signal generator so as to generate therewith a data acceptance clock signal having a clock frequency that is adapted in accordance with said ascertained clock frequency information; and (e) receiving said data signal in accordance with said data acceptance clock signal in said receiving unit; wherein said receiving unit includes an oscillator having an oscillator frequency that is substantially greater than a reciprocal of said respective pulse duration of said at least one synchronization pulse, and wherein said step of ascertaining said clock frequency information at least for a first time comprises generating with said oscillator a series of oscillator pulses at said oscillator frequency, comparing said respective pulse duration of said synchronization pulse with said oscillator frequency, counting the number of said oscillator pulses occurring during said respective pulse duration of said synchronization pulse to provide a count value corresponding to said number, and deriving said clock frequency information from said count value by using said count value as a representation of said respective pulse duration and deriving therefrom a current system clocking interval between a respective system clock signal pulse and a next successive system clock signal pulse. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33)
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- 34. A control system for transmitting digital data comprising a transmitter and a peripheral receiver including a clock signal frequency information acquisition circuit, a data acceptance clock signal generator with a controllable clock frequency and an oscillator, in which said transmitter transmits a synchronization pulse train including at least one synchronization pulse before transmitting the data to be transmitted, wherein the synchronization pulse train synchronizes said data acceptance clock signal generator in said receiver, wherein said clock signal frequency information acquisition circuit is clocked by said oscillator so as to acquire a clock frequency information contained within the synchronization pulse train and passes the clock frequency information to said clock signal generator, which in turn is clocked by the same said oscillator so as to generate a data acceptance clock signal corresponding to the clock frequency information, wherein said clock frequency information acquisition circuit comprises a first counter which ascertains the clock frequency information in the form of the number of the oscillator pulses of said oscillator to determine a count value, and wherein the count value of the oscillator pulses is provided further to said clock signal generator, which comprises a second counter that counts the number of the oscillator pulses and then respectively Generates a system clock signal upon reaching the count value.
Specification