Slave-type interface circuit operating with a series bus
First Claim
1. A slave type interface circuit for attaching to a serial bus having a data signal line (SDA) and a clock signal line (SCL), said circuit comprising:
- a plurality of addressing inputs (S0, S1, S2) for receiving present address bits (A0, A1, A2) for identifying the circuit in question;
a data input connectable (L1) to said data signal line;
a clock input (L2) connectable to said clock signal line;
a shift register (R0 . . . R7) connected to said data input and clock input for receiving data sequences and address sequences under synchronization by said clock signal line, said sequence being organized in bit cycles, each bit cycle having at least one sequence;
a memory (M) fed by parallel outputs of said shift register;
a first decoder (CDEC) fed by parallel outputs of said memory for generating decoded binary control signals for controlling user circuits (COM);
wherein said shift register has a downstream end output (QR8) for forwarding an end-of-sequence acceptance signal (ACN) to a data input of a first control flip-flop (DC1) clocked by said clock signal (SCL) and whose output (Q) synchronizes a second control or pointer flip-flop (PNT), whose inverted output (P) is retrocoupled to its input (D), in which the presence of a logic level "1" at the output (Q) of the first flip-flop (DC1) and at the output (P) of the pointer flip-flop enables an initialization of the shift register, which corresponds to the return of a predetermined initial state;
said circuit furthermore having resetting means for resetting said first and second control flip-flops under the control of an end-of-cycle detection signal (SDA) after said initialization;
wherein said circuit furthermore comprises;
a logic comparator (10, 11,
12) for comparing predetermined address bits present in said shift register (R0 . . . R7) and said preset address bits presented by said addressing inputs and upon correspondence producing an identification logic signal (DVA);
a storage circuit (66,
67) for storing said identification signal, in the form of a stored identification signal (ADC);
and logical AND gate means enabling the loading into the memory (M) of the data from the shift register when both the outputs of the first control flip-flop (DC1) and the pointer flip-flop (PNT) are in the logic state "1", and when also said stored identification signal (ADC) is present as well an end-of-sequence acceptance signal (ACN), signalling the end of a data sequence following said address sequence.
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Accused Products
Abstract
A slave-type interface circuit operating with a series bus in a configuration in which writing takes place after recognition of an address. A cycle transmitted by the bus contains an address sequence and a data sequence.
The circuit controls a plurality of user circuits (COM) on the basis of data stored in a memory (M) and of a decoder (CDEC).
A register (REG) and a bus logic (BUSL) receive at their inputs (L1, L2) information (SDA) and clock (SCL) signals. The bus logic (BUSL) receives from an identification circuit (AIC) a signal (DVA) indicating whether or not the address transmitted by the bus corresponds to an address A0, A1, A2 displayed at the inputs S0, S1 and S2. It controls the circuit on the basis of the register (REG) initialization signal (RST1), a signal LDS) for the authorization of the loading of data into the memory (M) and an acceptance signal (ACK) transmitted in the direction of the bus.
42 Citations
15 Claims
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1. A slave type interface circuit for attaching to a serial bus having a data signal line (SDA) and a clock signal line (SCL), said circuit comprising:
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a plurality of addressing inputs (S0, S1, S2) for receiving present address bits (A0, A1, A2) for identifying the circuit in question; a data input connectable (L1) to said data signal line; a clock input (L2) connectable to said clock signal line; a shift register (R0 . . . R7) connected to said data input and clock input for receiving data sequences and address sequences under synchronization by said clock signal line, said sequence being organized in bit cycles, each bit cycle having at least one sequence; a memory (M) fed by parallel outputs of said shift register; a first decoder (CDEC) fed by parallel outputs of said memory for generating decoded binary control signals for controlling user circuits (COM); wherein said shift register has a downstream end output (QR8) for forwarding an end-of-sequence acceptance signal (ACN) to a data input of a first control flip-flop (DC1) clocked by said clock signal (SCL) and whose output (Q) synchronizes a second control or pointer flip-flop (PNT), whose inverted output (P) is retrocoupled to its input (D), in which the presence of a logic level "1" at the output (Q) of the first flip-flop (DC1) and at the output (P) of the pointer flip-flop enables an initialization of the shift register, which corresponds to the return of a predetermined initial state; said circuit furthermore having resetting means for resetting said first and second control flip-flops under the control of an end-of-cycle detection signal (SDA) after said initialization; wherein said circuit furthermore comprises;
a logic comparator (10, 11,
12) for comparing predetermined address bits present in said shift register (R0 . . . R7) and said preset address bits presented by said addressing inputs and upon correspondence producing an identification logic signal (DVA);a storage circuit (66,
67) for storing said identification signal, in the form of a stored identification signal (ADC);and logical AND gate means enabling the loading into the memory (M) of the data from the shift register when both the outputs of the first control flip-flop (DC1) and the pointer flip-flop (PNT) are in the logic state "1", and when also said stored identification signal (ADC) is present as well an end-of-sequence acceptance signal (ACN), signalling the end of a data sequence following said address sequence. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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Specification