How to use the microcontroller STM32 extended SPI interface chip SRAM

STM32F1 series are low-end 32-bit ARM microcontroller core is Cortex-M3. The Flash chips by chip size can be divided into three categories: small capacity (16K and 32K), the capacity (64K and 128K), a large capacity (256K, 384K, and 512K). In the case of the actual application of the product shortage occurs if the built-in RAM that appears, select external expansion ram is the first choice of most engineers, of course, this MCU supports extended memory, extended memory optional SDRAM, FLASH, SRAM chips, extended SDRAM and FLASH is relatively simple, if you want to expand outside SRAM chip, then, is the current mainstream way to expand outside through a parallel port interface to SRAM chips, but the parallel port SRAM chips takes up too much I / O mouth, for limited use products pin design is proposed to consider the outer diffuser QPI interface or SPI interface SOP-8 package SRAM chips, may function to save pins, thereby achieving extended SRAM chip. The memory may be implemented VTI7064 manner singlet, 4 and 8-wire operation of the SRAM . Velocity between 20MHz ~ 200MHz, lower power consumption selecting the SPI SRAM, reducing power consumption to achieve more advantageous in the design of the product, the cost of the crystal than 6 SRAM has advantages much capacity is generally 16Mb, 32Mb , 64Mb. SPI SRAM because of cost advantage and MCU interface are recognized by many manufacturers and support.