Most of today’s smartphones use SIM cards to identify a subscriber, as well as to store personal data such as phone numbers and text messages. We’re probably all familiar with the little electronic card that the person behind the counter sticks into a new phone we buy at the carrier, or from moving it to your old phone to the glistening new handset you’re about to replace it with.
However, some (like me), are too intimately familiar with SIM cards because we are constantly moving them from one phone to another because of geographical (carrier and type of network) reasons, or to change the one phone you carry on a trip from your business SIM to your personal SIM.
Increasing in popularity, phones containing two SIM cards allow consumers to use different cellular networks to place and receive calls, data, texts, etc… Essentially, a dual SIM phone performs the function of two separate phone accounts in a single form factor. According to KPMG Research, dual SIM handsets are growing faster than other handsets. In the past, there were only three companies selling dual SIM phones; now there are about 40 companies in the market. These companies include Samsung, Nokia, LG, ZTE, Huawei and hTC, among others.
The tricky part with dual SIM phones is that they typically need two processors, which most support different radio standards (e.g. TD-SCDMA and HSDPA) to maximize functionality. Processors are always designed to be ‘master’ components in a system, always having control over everything. When designing a dual SIM phone, system designers are faced with the issue of inter-processor communication: two processors typically cannot communicate with each other as the processors are equipped with only the master controller interface. Furthermore, even if they can communicate directly, the issue of how to share the data can be very tricky when designing.
QuickLogic can solve this issue. Our ‘Inter-Processor Communication’ PSB (IPC for brevities sake), designed into a CSSP, allows for both direct and indirect communication. A CSSP with IPC allows two independent processors, whether from the same or different suppliers, to communicate with one-another without the risk of device processor ownership issues or failures. In the case of processors who can communicate with each other, IPC can be deployed to insure data sharing is correct, secure, and timely.
Add to that our standard PSB library of interfaces including UART, I2C, SPI, processor memory bus, SDIO, and USB , and QuickLogic CSSPs can offer system designers low cost, highly-functional solutions that address important needs.
