A system and a method for realizing I2C bus expansion by using a CPLD

Abstract

The invention provides a system and method for realizing I2C bus expansion by using a CPLD. The system comprises a BMC, a CPLD and a slave device. The method comprises the steps that firstly, the BMCcommunicates with the CPLD through a front-end I2C bus, and an internal register of the CPLD is configured through addressing action of the CPLD; Then, the configuration logic module analyzes the configuration data of the front-end I2C and outputs a control signal and a channel selection signal; and the channel control logic module establishes mapping between the front-end I2C wire and the rear-end I2C bus according to the control signal and the channel selection signal output by the configuration logic module. And finally, the BMC accesses the slave device connected with the rear-end I2C bus.Through the method, the device and the system, The CPLD is used for expanding the I2C bus, the hardware cost is reduced, the occupied PCB area is reduced, the circuit structure is simplified, the number of the expanded I2C paths can be configured according to the number of slave devices, no waste idle channel exists, the I2C address of the CPLD is 7-bit configurable, and the I2C address conflictis reduced.

Description

technical field [0001] The invention relates to the technical field of server I2C bus expansion, and specifically provides a system and method for implementing I2C bus expansion by using CPLD. Background technique [0002] In the server, BMC reads the alarm, voltage, temperature, hard disk information and firmware version number of each part through the I2C bus. There are many peripheral devices required to read information. However, the number of I2C interfaces of the BMC itself is small, which is not enough to meet the needs of the BMC to read all peripheral information. Therefore, it is necessary to add an expansion scheme of the I2C bus. In order to realize the I2C bus extension, a dedicated I2C switch chip is usually used to realize this function. [0003] The number of I2C extensions of existing I2C switch chips is fixed at 4 or 8 channels. In most cases, the required number of I2C extensions cannot be obtained by combining 4-way or 8-way chips. In order to meet th...

AI Technical Summary

Problems solved by technology

In most cases, the required number of I2C extensions cannot be obtained by combining 4-way or 8-way chips. In order to meet the functional requirements, a combination of I2C-way switch chips larger than the required number of expansions will be used, which will cause partial expansion. The I2C interface that comes out is idle and wasteful

At the same time, each switch chip requires a separate power supply, address configuration, enable signal, etc., resulting in a complex circuit structure and occupying more PCB space; the I2C address of the switch chip itself is set using an external pull-down resistor, and only 3 bits can be set , the configurable range is low, and address conflicts between chips are prone to occur

Use the hardware I2C switch chip to realize the expansion function of I2C, and the cost is relatively high

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