Datasheet
SAM9G20
DS60001516A-page 24 2017 Microchip Technology Inc.
• Automatic detection of valid application
• Bootloader on a non-volatile memory
- SDCard (boot ROM does not support high capacity SDCards.)
- NAND Flash
- SPI DataFlash and Serial Flash connected on NPCS0 and NPCS1 of the SPI0
- EEPROM on TWI
• SAM-BA
®
Boot in case no valid program is detected in external NVM, supporting
- Serial communication on a DBGU
- USB Device HS Port
7.1.1.2 BMS = 0, Boot on External Memory
• Boot on slow clock (On-chip RC or 32768 Hz)
• Boot with the default configuration for the Static Memory Controller, byte select mode, 16-bit data bus, Read/Write controlled by Chip
Select, allows boot on 16-bit non-volatile memory.
The customer-programmed software must perform a complete configuration.
To speed up the boot sequence when booting at 32 kHz EBI CS0 (BMS = 0), the user must take the following steps:
1. Program the PMC (main oscillator enable or bypass mode).
2. Program and start the PLL.
3. Reprogram the SMC setup, cycle, hold, mode timings registers for CS0 to adapt them to the new clock.
4. Switch the main clock to the new value.
7.2 External Memories
The external memories are accessed through the External Bus Interface. Each Chip Select line has a 256-Mbyte memory area assigned.
Refer to the memory map in Figure 7-1.
7.2.1 External Bus Interface
• Integrates three External Memory Controllers
- Static Memory Controller
- SDRAM Controller
- ECC Controller
• Additional logic for NAND Flash
• Full 32-bit External Data Bus
• Up to 26-bit Address Bus (up to 64 Mbytes linear)
• Up to 8 chip selects, Configurable Assignment:
- Static Memory Controller on NCS0
- SDRAM Controller or Static Memory Controller on NCS1
- Static Memory Controller on NCS2
- Static Memory Controller on NCS3, Optional NAND Flash support
- Static Memory Controller on NCS4–NCS5, Optional CompactFlash support
- Static Memory Controller on NCS6–NCS7
7.2.2 Static Memory Controller
• 8-, 16- or 32-bit Data Bus
• Multiple Access Modes supported
- Byte Write or Byte Select Lines
- Asynchronous read in Page Mode supported (4- up to 32-byte page size)
• Multiple device adaptability
- Compliant with LCD Module
- Control signals programmable setup, pulse and hold time for each Memory Bank