XIP mode is supported in most FLASH devices. Some of them use signature bits that are sent to the device immediately following the address bytes, other use signature bits and also require a FLASH device configuration register write to enable XIP. For the FLASH devices that must be compliant to the OSPI controller, the following steps can be taken by software to enter XIP mode:
- Disable the DAC and INDAC (OSPI_CONFIG_REG[7]
ENB_DIR_ACC_CTLR_FLD) to ensure no new data read accesses will be sent to
the FLASH device.
- (Optional) Configure the OSPI_FLASH_CMD_CTRL_REG
to issue a VCR write to FLASH memory, because XIP mode must first be enabled
for some devices.
- Configure the XIP mode bits in the
OSPI_MODE_BIT_CONFIG_REG[7-0] MODE_FLD bit field.
- Enable the local controllers XIP mode by setting
OSPI_CONFIG_REG[17] ENTER_XIP_MODE_FLD bit.
- Re-enable the DAC and, if required, the INDAC.