CN213338484U

CN213338484U - Safety chip

Info

Publication number: CN213338484U
Application number: CN202022664924.5U
Authority: CN
Inventors: 林万才; 徐立乾; 李明伟
Original assignee: JIANGSU DUWAN ELECTRONIC TECHNOLOGY CO LTD
Current assignee: JIANGSU DUWAN ELECTRONIC TECHNOLOGY CO LTD
Priority date: 2020-11-17
Filing date: 2020-11-17
Publication date: 2021-06-01
Anticipated expiration: 2030-11-17

Abstract

The utility model discloses a safety chip belongs to chip technical field. But do not take temperature compensation to the built-in clock signal of the safety chip that exists among the prior art, run into the encryption data processing chronometer that has the accurate time reliable inadequately, use the not high problem of outside clock signal security, the utility model provides a safety chip, built-in high accuracy clock module runs into under the condition that needs use the accurate time, can directly use the built-in clock signal of safety chip, and the outside can't change. The clock module is provided with the crystal oscillator and the digital temperature compensation, the error of the clock module is compensated according to different temperatures, the user intervention is not needed in the normal temperature and wide temperature range, the precision is less than +/-3.8 ppm at 25 ℃, the reliability is high, and the safety is high.

Description

Safety chip

Technical Field

The utility model relates to a chip technical field, more specifically say, relate to a safety chip.

Background

The safety chip is used as a safe case, the most important password data is stored in the safety chip, and some safety chips encrypt the data and store the encrypted data in another memory, and then complete the seed safety protection work by matching with management software. And according to the principle of the security chip, because the password data can only be output but not input, the encryption and decryption operations are completed in the security chip, and only the result is output, thereby avoiding the chance of password cracking.

A high-precision clock signal is not arranged in a traditional safety chip, and the requirement can not be met for data with precise time when encryption is carried out. If an external clock signal is used, the clock signal is at risk of being altered.

The chinese patent applies for a security chip embedded with a real-time clock and a method for calibrating the real-time clock, application No. 200510055892.6, published 2008, 12 and 31, and discloses a security chip embedded with a real-time clock, comprising: the real-time clock device is used for providing the current time value of the security chip for the data file as a timestamp mark; an external frequency generator for providing a reference clock frequency for the real-time clock device; clock calibration means for correcting errors of said real time clock means to achieve clock synchronization; the encryption device is used for generating a secret key according to an encryption algorithm so as to realize the security protection and authentication of the reading and writing of the security chip; and the MCU is used for providing operation support and management for the chip operating system. In addition, the invention also discloses a method for correcting the real-time clock of the security chip. The safety chip not only provides a non-repudiation time stamp for the data signature, but also can use the time information for various safety services related to time, so that the functions of the safety chip are more complete, however, the safety chip of the invention has no temperature compensation, has insufficient calibration accuracy, cannot process data with high precision requirement, and has low reliability.

Disclosure of Invention

1. Technical problem to be solved

But do not take temperature compensation to the built-in clock signal of the safety chip that exists among the prior art, run into the encryption data processing chronometer that has the accurate time reliable inadequately, use the not high problem of outside clock signal security, the utility model provides a safety chip, it can realize setting up high accuracy clock signal in safety chip inside, still takes temperature compensation certainly, can directly use the inside clock signal of safety chip when needing the accurate clock, supports two kinds of local and long-range calibration methods simultaneously, and the security is high.

2. Technical scheme

The purpose of the utility model is realized through the following technical scheme.

A safety chip comprises an MCU and a clock module, wherein an input/output port of the MCU is connected with an input/output pin in the clock module, and the clock module controls the MCU to time through the input/output pin; the clock module is internally provided with a digital temperature sensor, a crystal oscillator and a resonant capacitor, the temperature sensor converts the temperature into a digital signal and sends the digital signal to the clock module, and the resonant capacitor is a compensation capacitor of the crystal oscillator. The utility model discloses built-in crystal oscillator and resonance electric capacity, chip inside through high accuracy compensation method, realize the timing function at wide temperature range high accuracy, wherein 25 ℃ precision < + > +/-3.8 ppm.

Furthermore, the number of the crystal oscillators is at least one. The resonant capacitor is connected to two ends of the crystal oscillator as a compensation capacitor, which is also called a load capacitor. When the oscillation frequency of the crystal oscillator is influenced by the change of the environmental temperature, the circuit selects and connects a proper compensation capacitor, so that the offset caused by the temperature change can be reduced, and the oscillation frequency of the crystal oscillator is stabilized. Generally, increasing the compensation capacitance decreases the oscillation frequency of the crystal oscillator, and decreasing the compensation capacitance increases the oscillation frequency of the crystal oscillator.

Furthermore, the clock module also comprises a backup battery input pin VBAT, a charging circuit with voltage stabilization and charging current selection is arranged in the clock module, and the clock module is connected with the backup battery through the pin VBAT.

Furthermore, the time module also comprises an alarm interruption output pin INT, and the pin INT sets the working mode according to the register.

Furthermore, the memory of the security chip is provided with an ID code, and the ID code is an eight-byte chip identity identification code.

Furthermore, the data receiving port and the data transmitting port of the MCU are also connected with the universal asynchronous receiver-transmitter. The MCU realizes the control of the clock module through the universal asynchronous receiver-transmitter.

Further, the chip package is in the form of SOP 8. And the width is 208 mil.

Furthermore, the chip register comprises a real-time clock register, a time alarm register and a control register, wherein the real-time clock register stores clock data in a BCD code mode, the time alarm register stores alarm interrupt data at different times, and the data of the control register enables the alarm interrupt data in the time alarm register.

Furthermore, the security chip further comprises a filter, wherein the filter comprises at least one capacitor, and the capacitors are connected in parallel.

Further, the filter further comprises an electrolytic capacitor.

The utility model relates to a safe chip of built-in high accuracy clock function is inside mainly to adopt the MCU of a low-power consumption and the real-time clock module of a high accuracy, and the secret second grade authentication of this MCU accessible state, security are high. The clock module adopts a high-precision real-time clock module, and the output frequency is 32.768 kHz. The MCU passes through the universal asynchronous receiver-transmitter I²The C interface controls the output of the clock module and is packaged by using a SOP8 form.

The utility model discloses safe chip embeds crystal oscillator and resonant capacitor and takes digital temperature compensation certainly, and two kinds of modes are supported in the clock calibration, including long-range school time and local school time, can realize not needing user's intervention in normal atmospheric temperature and wide temperature range, automatic reliable timing sets up the ID sign indicating number in the memory, can carry out identification, improves the security of chip.

3. Advantageous effects

Compared with the prior art, the utility model has the advantages of:

a high-precision clock module is arranged in the safety chip, and when the accurate time needs to be used, the clock signal arranged in the safety chip can be directly used, and the outside cannot be changed. The clock module is provided with a crystal oscillator and digital temperature compensation, the error of the clock module is compensated according to different temperatures, and the clock module can automatically and reliably time at normal temperature and in a wide temperature range without user intervention. The clock calibration supports two modes, including remote time calibration and local time calibration, in order to prevent the time of the security chip from being tampered, the MCU performs time calibration at most once every day, and only can perform time calibration forwards, otherwise, the time is considered to be illegally modified, and the calibration action is not executed. The safety chip of the embodiment has high reliability and strong safety under the condition of needing to use accurate time, uses the resonance capacitor to carry out digital temperature compensation, has low power consumption, does not have too large limitation on the size of the chip, and is suitable for wide application.

Drawings

Fig. 1 is a schematic structural view of the present invention;

fig. 2 is a circuit connection diagram of the present invention.

Detailed Description

The invention is described in detail below with reference to the drawings and specific examples.

Example 1

Fig. 1 is a schematic structural diagram of a security chip with a built-in high-precision clock function, where the chip shown in fig. 1 includes a clock module, and an MCU is connected to the clock module to form a security chip, and the chip has a built-in high-precision clock module, and is highly reliable in computation when performing data processing with a high precision requirement. The clock module of the embodiment is internally provided with a digital temperature sensor with an 8-bit conversion result, a crystal oscillator and a resonant capacitor, and the internal part realizes a high-precision timing function in a wide temperature range by a high-precision compensation method, wherein the precision of 25 ℃ is less than +/-3.8 ppm.

The clock module is a real-time clock chip with standard IIC interface in this embodiment, and the maximum speed is 400 KHZ. The crystal oscillator and the digital temperature compensation are built in, the element matching error problem, the crystal oscillator temperature characteristic problem and the reliability problem caused by the external crystal oscillator, the resonant capacitor and the like are not considered, and the full-automatic and high-reliability timing function without user intervention in normal temperature and wide temperature range is realized. The safety chip of the embodiment realizes BCD code input/output of year, month, day, week, hour, minute and second, can access each time register through independent addresses, is internally provided with an alarm data register with 7 bytes of year, month, day, week, hour, minute and second and an alarm permission register with 1 byte, has 96 combined alarm modes in total, has two interrupt output modes of single-event alarm and periodic alarm, and can set the alarm time as 100 years to the maximum. The time can automatically recharge a 24-bit countdown timer with three bytes, the minimum timing is 244us, the maximum timing can reach 31 years by 4 optional clock sources, and a relatively accurate millisecond-level timing value can be obtained through calculation.

Fig. 2 is a circuit connection diagram of a security chip, in which U1 represents a clock module, U2 represents an MCU, and U1 and U2 are connected, in this embodiment, U1 uses an MCU with low power consumption, and the MCU can pass national security two-level authentication and has high reliability; u2 uses a high precision real time clock module. When the MCU is connected with the clock module, a pin GPIOB1 of the MCU is connected with a pin SDA in the clock module through a resistor R1, the resistance value of the resistor R1 is 2.2k omega, the pin GPIOB1 is a universal input/output interface of the MCU, the pin SDA is a serial input/output pin of the clock module, and the clock module controls the MCU in a timing way through the pin SDA. And other IO ends of the MCU are also connected with the outside to receive control signals input from the outside.

Pins OSCOUT and OSCIN of the clock module are connected with a crystal oscillator, and the frequency of the crystal oscillator is 32768 Hz. And a pin SCL in the clock module is a serial clock input pin and is connected with a clock, so that high-precision timing of the safety chip is realized. The pin K32 of the clock module outputs a control bit of 32K, the default value is 0, when the 32K is 0, the output is allowed, and when the 32K is 1, the output is forbidden. The time module has a base pin INT as an alarm interruption output pin, inhibits the clock module from working by rewriting the control register, and sets a working mode according to the control register, wherein the clock module comprises three different time alarm interruptions, namely an alarm interruption, a frequency interruption and a countdown interruption.

And a pin VPS of the clock module is connected with a 3.3V power supply, and a pin GND is grounded. The clock module also comprises a backup battery input pin VBAT, a charging circuit with voltage stabilization and charging current selection is arranged in the clock module, and the clock module is connected with the backup battery through the pin VBAT. The clock module automatically switches from power supply voltage to VBAT or from VBAT to power supply voltage according to different voltages, and when the clock module detects that the main power supply falls below a fixed value and the power supply voltage is smaller than VBAT, the clock module can be powered by a backup battery connected to VBAT; when the power voltage is greater than VBAT or the power voltage is greater than a fixed value, the chip is powered by the power voltage. When the backup power is activated, pin SCL is disabled.

A pin VDD of the MCU is connected with a 3.3V power supply, and a pin URRT1_ TX is a data sending end; the pin URRT1_ RX and the pin URRT2_ RX are both data receiving ends, wherein the pin URRT1_ RX is connected with UART, and the pin URRT2_ RX is connected with GPS; a pin RESETN is a reset end; the pin URRT1_ TX, the pin URRT1_ RX, the pin URRT2_ RX and the pin RESETN are all connected with the universal asynchronous receiver/transmitter J1, and the MCU controls the output of the clock module through the universal asynchronous receiver/transmitter J1. The port 1 of J1 is connected with 3.3V power supply, the port 2 is connected with the pin URRT1_ TX of MCU, the port 3 of J1 is connected with the pin URRT1_ RX of MCU, the port 4 of J1 is connected with the pin URRT2_ RX of MCU, the port 5 of J1 is connected with the pin RESETN of MCU, and the port 6 of J1 is grounded.

The MCU is connected with the clock module, the clock module calibrates a clock source of the MCU, in order to prevent the time of the security chip from being tampered, the MCU is set to calibrate the time at most once every day during application, and only calibration can be carried out forwards, the data of the time calibration needs to be within a certain range, the time calibration threshold is generally several minutes, the time calibration is considered to be illegal modification time when the time calibration threshold exceeds the threshold or the time calibration is carried out backwards, and the calibration action is not executed. The safety chip of the built-in clock module has a unique identification ID code, so that tampering is prevented. The identification code of the chip comprises eight bytes, is set and unique before the safety chip leaves a factory, and comprises contents such as production date, internal batch number, internal serial number and the like. The clock module is provided with a crystal oscillator and a resonance capacitor, the resonance capacitor is a compensation capacitor sequence of the crystal oscillator, errors of the clock module are compensated through different temperatures acquired by the temperature sensor, and automatic and reliable timing can be realized without user intervention in normal temperature and wide temperature range.

The circuit of the embodiment is also connected with a power supply filter in parallel, wherein the power supply filter comprises six capacitors C1-C6, and all the six capacitors are connected in parallel, wherein the capacitors C1, C2 and C3 are electrolytic capacitors and have the specification of 22 muF; the capacitors C4, C5 and C6 are common capacitors and are all 0.1 muF.

The security chip of the embodiment is packaged by using a form of SOP8, and the width of the security chip is 208 mil. The built-in high-precision clock module is provided with the crystal oscillator and the temperature compensation, the accuracy of the clock is guaranteed, the clock has the unique identification code, the safety is high, the safety chip supports two local and remote timing modes, the reliability is high, the resonance capacitor is used for carrying out digital temperature compensation, the power consumption is low, the size of the chip is not greatly limited, and the clock is suitable for wide application.

The invention and its embodiments have been described above schematically, without limitation, and the invention can be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The representation in the drawings is only one of the embodiments of the invention, the actual construction is not limited thereto, and any reference signs in the claims shall not limit the claims concerned. Therefore, if a person skilled in the art receives the teachings of the present invention, without inventive design, a similar structure and an embodiment to the above technical solution should be covered by the protection scope of the present patent. Furthermore, the word "comprising" does not exclude other elements or steps, and the word "a" or "an" preceding an element does not exclude the presence of a plurality of such elements. Several of the elements recited in the product claims may also be implemented by one element in software or hardware. The terms first, second, etc. are used to denote names, but not any particular order.

Claims

1. A safety chip is characterized by comprising an MCU and a clock module, wherein an input/output port of the MCU is connected with an input/output pin in the clock module, and the clock module controls the MCU to time through the input/output pin; the clock module is internally provided with a digital temperature sensor, a crystal oscillator and a resonant capacitor, the temperature sensor converts the temperature into a digital signal and sends the digital signal to the clock module, and the resonant capacitor is a compensation capacitor of the crystal oscillator.

2. The security chip according to claim 1, wherein said crystal oscillator is at least one.

3. The security chip of claim 2, wherein the clock module further comprises a backup battery input pin VBAT, and the clock module has a charging circuit with voltage regulation and charging current selection, and the backup battery is connected through the pin VBAT.

4. A security chip according to claim 3, characterized in that the time module further comprises an alarm interrupt output pin INT, which sets the operating mode according to a register.

5. The security chip according to claim 1, wherein the memory of the security chip is provided with an ID code, and the ID code is an eight-byte chip identification code.

6. The security chip according to claim 1, wherein the data receiving port and the data transmitting port of the MCU are further connected to a universal asynchronous receiver/transmitter.

7. A security chip as claimed in claim 1, wherein said chip is packaged in the form of an SOP 8.

8. The security chip of claim 1, wherein the security chip further comprises registers, the registers include a real-time clock register, a time alarm register, and a control register, the real-time clock register stores clock data in a BCD code manner, the time alarm register stores alarm interrupt data at different times, and the data of the control register enables the alarm interrupt data in the time alarm register.

9. A security chip according to claim 1, wherein said security chip further comprises a filter comprising at least one capacitor connected in parallel.

10. A security chip as claimed in claim 9, wherein said filter further comprises an electrolytic capacitor.