How to select the large capacity memory chip by using RTOS System

With the rising of IOT market, many electronic products are required boot fast, low power consumption and timely response. Therefore, RTOS (such as RT Thread) has been used more and more widely. The RTOS system are mainly used in professional and delicate product, so the system images are very small, basically<10MB, or even<1MB. But sometimes developers need to:

1. Use GUI interface to store pictures

2. Need to store a startup or prompt voice/video

3. The system needs to embedded some protocol stacks

For above reasons, the IMG system becomes very large, and NOR Flash is not enough for the capacity. So we have to use NAND Flash. However, there are several problems with using Raw NAND:

1. CPU needs to support parallel ports;

2. CPU is required to perform EDC/ECC, bad block management, average read/write and other operations. The CPU performance which using RTOS is relatively limited. So, it is right to choose a NAND Flash product with controller.

At present, the mainstream NAND Flash with controller products are SD NAND, eMMC, T card, etc. For RTOS users, SD NAND is preferred to recommended for the following reasons:

1. The capacity of SD NAND is mainly 128MB/512MB/4GB/8GB, which is sufficient for the capacity and the cost is reasonable.

2. The size for SD NAND is smaller than T card and eMMC (6 * 8mm WSON-8 package)

3. SD NAND is convenient for welding with only 8 pins. In contrast, eMMC is BGA 153 balls; The T card itself is not suitable for welding.