Research Of Dual-core Architecture Communication Technology For Smart Phone

Mobile phone is a typical embedded system, the infrastructure of traditional phone is usually single-core based, which means one processor runs a Real Time Operating System (RTOS), on RTOS also runs communication protocol stack and applications. Smartphone is usually based on dual-core architecture, one low speed processor runs RTOS and communication protocol, another high speed processor runs smartphone operating system and applications. Because of dual-core infrastructure, there's problem how to communicate between two processors. The communication between two processor now usually based on UART interface, this can utilize exist processor interface, easy to design and implement. The disadvantage of this is: UART is slow, inefficient and high cost. So how to design a dual-core communication solution with high speed and low cost capability becomes a subject.This article designed CSMI(Coprocessor Shared Memory Interface) system based on register and share memory. CSMI is a software module on TI OMAP 730, is implemented on both application processor and baseband processor. It create a virtual bi-directional communication channel between application processor and base band processor, the two processor can exchange message and data fast and cost effective using CSMI.Based on the main requirement of dual-core communication, CSMI defines 9 channels, with two types of services: mailbox and data stream. Each channel is introduced in detail. CSMI communication device is composed by ICR control register, ICR share memory, and system memory buffer. Each communication device is analyzed and introduced. The mechanism of CSMI communication is researched, the mechanism and process of mailbox channel and data stream channel is introduced with some examples of message. At last, the test reports for all the functionalities are listed, proving all the functionalities are implemented, and the performance of packet data transfer is much better than traditional UART solution. The solution based on the research of this article has been implemented on Lenovo's smartphone that is on the market now. This solution improves the cost and communication efficiency a lot for dual-core communication, it will be applied to future dual-core system more and more.