Photocoupler Data Link Synchronization With Differential Manchester Encoding
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Solution Overview
Problem
In optical data transmission using photocouplers, asynchronous conditions between the transmission and reception sides can lead to data errors due to transmission delays.
Innovation Solution
A semiconductor device with a frequency conversion circuit, differential Manchester encoding, and an error detection circuit that oversamples and synchronizes data at the reception side, using photocouplers for optical transmission and demodulation, to reduce data errors by ensuring high reliability of sample data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If optical transmission using photocoupler is performed, then data transmission capability is improved, but transmission delay causes asynchronism between transmission and reception sides
Solution Approach 1:
The patent applies feedback by transmitting a clock signal from the reception side back to the transmission side through a second photocoupler. The reception side generates a clock signal based on received data and transmits it back, allowing the transmission side to synchronize its data transmission timing with the reception side's processing节奏, thereby resolving the asynchronism problem caused by transmission delays
Solution Approach 2:
The patent introduces a clock signal as an intermediary element that mediates between the transmission and reception sides. This clock signal serves as a reference timing signal that both sides use to synchronize their operations, acting as a common reference that coordinates the asynchronous operations and eliminates data errors caused by timing mismatches
2Speed
If transmission delay occurs during data transmission, then asynchronism between transmission and reception sides occurs, but data errors may occur at reception side
Solution Approach 1:
The feedback mechanism of transmitting the clock signal from reception to transmission side enables continuous synchronization. The transmission side uses the received clock signal to adjust its data transmission timing, ensuring that data is sampled at the reception side at the optimal moment, thereby preventing data errors even when transmission delays occur
Solution Approach 2:
The patent performs preliminary synchronization by establishing a clock signal transmission path before actual data transmission. This preliminary action of setting up the timing reference ensures that both sides are synchronized from the beginning, preventing data errors before they can occur during the main data transmission process
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The semiconductor device effectively reduces the possibility of data errors at the reception side by synchronizing data transmission and reception through differential Manchester encoding and error detection, even when the transmission and reception sides are asynchronous.
Implementation Method 1
a first photocoupler 3, in which a clock Ck1 generated by a frequency conversion circuit 2 on the transmission side is optically transmitted to a reception side
Implementation Method 2
a second photocoupler 6, in which encoded data D1, obtained by an encoding circuit 5 on the transmission side, is optically transmitted to the reception side
Implementation Method 3
The first light receiving element 32 outputs the clock Ck1 to an ADC 4 and to the encoding circuit 5. The second light receiving element 62 outputs, to a demodulating circuit 7, light reception data D2 which is the encoded data D1 optically received by the second light receiving element 62
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A semiconductor device of an embodiment includes first and second couplers, an encoding circuit, and a demodulating circuit. The encoding circuit executes differential Manchester encoding on digital data based on a clock inputted thereto via the first coupler and outputs an encoded data. The demodulating circuit includes a first sampling circuit which samples the encoded data inputted via the second coupler based on a sampling frequency set to be two times higher than that of the encoded data and which outputs first sample data, a second sampling circuit which samples the encoded data at a timing earlier than that in the first sampling circuit and which outputs second sample data, a determination circuit which determines whether or not the first and the second sample data match each other, and a selection circuit which selects first phase data or second phase data from the first sample data.