9.2.1 External Bus Interface

The External Bus Interface (EBI) is a 16-bit-wide interface working at MCK/2.

The EBI supports:

• Static memories
• 8-bit NAND Flash with 32-bit BCH ECC
• 16-bit NAND Flash

EBI I/Os accept three drive levels (Low, Medium, High) to avoid overshoots and provide the best performances according to the bus load and external memories voltage.

The drive levels are configured with the DRVSTR field in the PIO Configuration Register (PIO_CFGRx) if the corresponding line is nonsecure or the Secure PIO Configuration Register (S_PIO_CFGRx) if the I/O line is secure.

At reset, the selected drive is low. The user must make sure to program the correct drive according to the device load. The I/O embeds serial resistors for impedance matching.