Datasheet

419
SAM3X / SAM3A [DATASHEET]
Atmel-11057C-ATARM-SAM3X-SAM3A-Datasheet_23-Mar-15
25. Static Memory Controller (SMC)
25.1 Description
The External Bus Interface is designed to ensure the successful data transfer between several external devices
and the Cortex-M3 based device. The External Bus Interface of the SAM3X consists of a Static Memory Controller
(SMC).
This SMC is capable of handling several types of external memory and peripheral devices, such as SRAM,
PSRAM, PROM, EPROM, EEPROM, LCD Module, NOR Flash and NAND Flash.
The SMC generates the signals that control the access to external memory devices or peripheral devices. It has 8
Chip Selects and a 24-bit address bus. The 16-bit data bus can be configured to interface with 8- or 16-bit external
devices. Separate read and write control signals allow for direct memory and peripheral interfacing. Read and
write signal waveforms are fully parametrizable.
The SMC can manage wait requests from external devices to extend the current access. The SMC is provided with
an automatic slow clock mode. In slow clock mode, it switches from user-programmed waveforms to slow-rate
specific waveforms on read and write signals.
The SMC embeds a NAND Flash Controller (NFC). The NFC can handle automatic transfers, sending the
commands and address cycles to the NAND Flash and transferring the contents of the page (for read and write) to
the NFC SRAM. It minimizes the CPU overhead.
The SMC includes programmable hardware error correcting code with one bit error correction capability and
supports two bits error detection. In order to improve overall system performance the DATA phase of the transfer
can be DMA assisted.
The External Data Bus can be scrambled/unscrambled by means of user keys.