SPI0 external RAM DDR write command control register
CACHE_SRAM_USR_WR_CMD_VALUE | When SPI0 writes Ext_RAM, it is the command value of CMD phase. |
CACHE_SRAM_USR_WR_CMD_BITLEN | When SPI0 writes Ext_RAM, it is the length in bits of CMD phase. The register value shall be (bit_num-1). |