Read-write protection circuit

Abstract

Embodiments of the invention provide a read-write protection circuit which mainly comprises a memory and a control circuit. The control circuit is provided for determining electric source received by the memory. The memory is provided with a pin for determining an access state of the memory. When the pin receives a high level voltage, the access state of the memory is set as a read-only state; when the pin receives a low level voltage, the access state of the memory is set as a readable-writable state. With the design of the control circuit provided by the present invention, a user of a manufacturing terminal can read and write data in the memory conveniently, and a user of a whole machine terminal only can read the data in the memory.

Description

technical field [0001] The invention relates to a read-write protection circuit, in particular to a read-write protection circuit which is read-write at the manufacturing end and read-only at the user end. Background technique [0002] General electronic products, such as computers and liquid crystal displays, usually have a chip for recording relevant information required by the product or production. [0003] For example, the printed circuit board of the display panel of a notebook computer or monitor usually has an Electrically Erasable Programmable Read-Only Memory (EEPROM) chip, which records the extended display identification data ( Extended display identification data, EDID), which is a data format provided by the display panel, records data such as specifications that can be supported by the computer's display card (graphics card), and its recorded format conforms to the Video Electronics Standards Association (Video Electronics Standards Association, VESA) standar...

AI Technical Summary

Problems solved by technology

[0006] However, the chips used to record product and production information in today's consumer electronics products, such as the above-mentioned EEPROM, cannot meet the requirements of both readable and writable and read-only. Usually, this memory has a power pin for Receive the operating voltage to drive the memory, the two signal pins are used to receive the clock signal and data signal to read EDID data, and the setting pin is used to control the access state of the memory; generally speaking, the control mechanism of the memory will It is designed so that the memory is read-only when the setting pin receives a high level voltage, and the memory is readable and writable when it receives a low level voltage

However, as mentioned above, in order to ensure that the display panel manufacturer can "read and write" the memory, that is, even if the state of the memory is readable and writable, it is known that the memory setting pin is permanently fixed to receive a low level voltage, so that the memory Remain in a readable and writable state; thus, at the end of the user, such as a computer manufacturer, the recorded data in the memory is at risk of being altered

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