Abstract: A method for executing a write command for writing a binary word in a programmable memory, comprises writing each of the bits in a programmed state of a binary word to be written in a corresponding memory cell of the memory, reading each bit of the word written in the memory corresponding to a bit in the programmed state of the word to be written, comparing each bit in the programmed state of the word to be written with a corresponding bit read in the memory, and generating an error signal if at least one bit of the word to be written in the programmed state is different from the corresponding bit read. Application of the method can be particularly but not exclusively to integrated circuits for chip cards.

Abstract: A method divides a number N1 by a number which can be written in the form 2n/k, n and k being whole numbers, and obtains a result N2. The result N2 is calculated by adding terms N1*Ki/2n-i for i ranging from 0 to N, the terms Ki being the constituent bits K0, K1, K2, . . . KN-1 of the number k expressed in binary. The method can be applied particularly to the production of a calibration circuit for calibrating a clock signal in a UHF transponder.

Abstract: A method for generating a variable number includes generating a clock signal, demodulating a received signal of data transmission, supplying a binary signal having variable frequency pulses, and sampling the clock signal by the binary signal to generate bits of a variable number. The method can be applied to RFID tags.

Abstract: A method protects against a global data erasure an integrated circuit comprising an electrically programmable data memory and a control unit to execute commands for reading or writing in the memory. The method comprises the steps of providing, in the integrated circuit, electrically programmable reference memory cells, at putting the integrated circuit into service, storing, in the reference memory cells, bits of determined value forming an authorized combination of bits and, during the operation of the integrated circuit following its putting into service, reading and evaluating the reference memory cells and blocking the integrated circuit if the reference memory cells contain a forbidden combination of bits different from the authorized combination.

Abstract: A method checks the state of a set of memory cells of a memory comprising memory cells arranged in a memory array, means for selecting a memory cell, and a sense amplifier for supplying a state of the selected memory cell depending on whether the selected memory cell is conductive or non-conductive. The method includes features wherein all the memory cells of a set grouping together several memory cells are selected, and then simultaneously coupled to the sense amplifier, and the sense amplifier supplies a global state of all the selected memory cells to which it is coupled, if the latter are simultaneously non-conductive. Application is provided to the checking of a command for block-erasing a memory.

Abstract: A start-detection circuit and a stop-detection circuit detect the start condition and the stop condition in a data signal associated with a clock signal according to the IIC protocol. The start-detection circuit comprises: a first detector to produce a first reset signal when a trailing edge of the data signal is detected; a counter to count pulses of a reference signal when the first reset signal is received, and to produce an enabling signal when the number of pulses counted has reached a predefined number; a second detector to store the enabling signal when a trailing edge of the clock signal is detected. The stop-detection circuit comprises a third detector to produce a stop signal when a leading edge of the data signal is detected after the detection of a leading edge of the clock signal.

Abstract: A method is provided for decoding an encoded binary data signal and generating a clock signal that is synchronous with the encoded data signal. There is generated, from the encoded data signal, an edge detection signal comprising four pulses per binary state of the encoded data signal. The encoded data signal is sampled every four pulses of the edge detection signal so as to obtain a binary signal of decoded data, and from the edge detection signal there is generated a binary clock signal that is synchronous with the encoded data signal and changes logic state every two pulses of the edge detection signal.

Abstract: The invention concerns non-contact smart cards and, more particularly in such cards, a circuit for detecting data frames and providing them with a parallel format for their processing. The invention is characterised in that it consists in using the information contained in the first octets of the frame being currently received, thereby enabling to identify them as they are received and route them into registers (80). This is provided by a state machine (60) whereof the shift from one state to the other is switched by the circuitry (62, 76) output signals.

Abstract: A contactless integrated circuit receiving an RF signal comprises a clock-signal generator to produce a clock signal from a first half wave and a second half wave representing the received RF signal. Also disclosed is a method for the generation of a clock signal in which the first half wave and the second half wave are compared to produce the clock signal. The invention is adapated for use in contactless cards, transponders, and the like.

Abstract: A buffer of reduced size includes a logic gate to raise the potential level of input digital data having a first logic level to a potential equal to a low power supply potential, and to produce intermediate data if a validation signal is active. The buffer also includes a tristate inverter to produce output data, at an output, that are logically inverse to the intermediate data if the validation signal is active and having its output at high impedance if otherwise. Such a buffer is particularly useful as an output buffer for contact cards using a power supply potential different from a potential powering a reader with which the card communicates.

Abstract: An integrated circuit having an identification code of M bits includes a communication interface circuit for receiving a selective identification request and a selection code, and a processing circuit connected thereto. The processing circuit includes a logic comparator having a first input for receiving the selection code and a second input for receiving the identification code, and an output for delivering an equal signal if the selection and identification codes are equal. A shift register has an output coupled to the first input of the logic comparator. A serial memory stores the identification code, and has a serial output coupled to the second input of the logic comparator and to a serial input of the shift register. A controller is connected to the shift register and to the serial memory for loading the selection code into the shift register, and for applying M shift pulses to the shift register and M read pulses to the serial memory.

Abstract: A device for detecting a defective power supply connection in an integrated circuit includes a comparison circuit for comparing voltage levels of an input/output pad of the integrated circuit and an internal power supply line connected to a power supply pad of the integrated circuit. A pull-down or pull-up device is connected between the input/output pad and the internal power supply line.

Abstract: The circuit for detecting the frequency of binary signals includes a circuit for detecting rising edges in the binary signals, a measuring circuit for measuring the period between the rising edges which supplies a logic state, and a shift register whose input latch stores the logic state. Also, the detecting circuit includes a shift circuit for shifting logic states of the shift register, and a decoding circuit for decoding logic states of the register, and which supplies a signal validating the signals. The detecting circuit can be used in contactless chip card readers.

Abstract: A start-detection circuit and a stop-detection circuit detect the start condition and the stop condition in a data signal associated with a clock signal according to the IIC protocol. The start-detection circuit comprises: a first detector to produce a first reset signal when a trailing edge of the data signal is detected; a counter to count pulses of a reference signal when the first reset signal is received, and to produce an enabling signal when the number of pulses counted has reached a predefined number; a second detector to store the enabling signal when a trailing edge of the clock signal is detected. The stop-detection circuit comprises a third detector to produce a stop signal when a leading edge of the data signal is detected after the detection of a leading edge of the clock signal.

Abstract: A buffer of reduced size includes a logic gate to raise the potential level of input digital data having a first logic level to a potential equal to a low power supply potential, and to produce intermediate data if a validation signal is active. The buffer also includes a tristate inverter to produce output data, at an output, that are logically inverse to the intermediate data if the validation signal is active and having its output at high impedance if otherwise. Such a buffer is particularly useful as an output buffer for contact cards using a power supply potential different from a potential powering a reader with which the card communicates.

Abstract: A contactless integrated circuit includes a voltage generator (11, 12, 13) to produce a power supply voltage (VDD) from a received RF signal. A starting circuit for the contactless integrated circuit produces a disabling signal (POR) until the power supply voltage (VDD) reaches a first voltage threshold (VS1) The starting circuit further produces the disabling signal (POR) when the power voltage (VDD) falls below a second voltage threshold (VS2) that is lower than the first voltage threshold (VS). The starting circuit has application for use in connection with chip cards, transponders, and the like.

Abstract: An integrated circuit having an identification code of M bits includes a communication interface circuit for receiving a selective identification request and a selection code, and a processing circuit connected thereto. The processing circuit includes a logic comparator having a first input for receiving the selection code and a second input for receiving the identification code, and an output for delivering an equal signal if the selection and identification codes are equal. A shift register has an output coupled to the first input of the logic comparator. A serial memory stores the identification code, and has a serial output coupled to the second input of the logic comparator and to a serial input of the shift register. A controller is connected to the shift register and to the serial memory for loading the selection code into the shift register, and for applying M shift pulses to the shift register and M read pulses to the serial memory.

Abstract: A device for detecting a defective power supply connection in an integrated circuit includes a comparison circuit for comparing voltage levels of an input/output pad of the integrated circuit and an internal power supply line connected to a power supply pad of the integrated circuit. A pull-down or pull-up device is connected between the input/output pad and the internal power supply line.

Abstract: The circuit for detecting the frequency of binary signals includes a circuit for detecting rising edges in the binary signals, a measuring circuit for measuring the period between the rising edges which supplies a logic state, and a shift register whose input latch stores the logic state. Also, the detecting circuit includes a shift circuit for shifting logic states of the shift register, and a decoding circuit for decoding logic states of the register, and which supplies a signal validating the signals. The detecting circuit can be used in contactless chip card readers.