Board Description
4-4
AT91SAM9M10-G45-EK User Guide
6495B–ATARM–21-Apr-10
4.2.2
Clock Circuitry
The SAM9M10-G45-EK includes six clock sources:
Two are alternatives for the SAM9M10 main clock,
One crystal and one crystal oscillator are used for the Ethernet MII/RMII chip,
One crystal is used for the AC97 codec chip,
One crystal or one crystal oscillator is used for the TV encoder.
4.2.3
Reset Circuitry
The reset sources are:
Power on reset
Push button reset
JTAG reset from an in-circuit emulator interface.
4.2.4
Memory
4.2.4.1
External Memories
The SAM9M10 features a DDR2/LPDDR memory interface and an External Bus Interface (EBI) to permit
interfacing to a wide range of external memories and to almost any kind of parallel peripheral.
The SAM9M10-G45-EK board is equipped with DDR2/LPDDR devices featuring 128 MB of DDR2-
SDRAM memory (16Meg*8*4).
The External Bus Interface (EBI) is connected to three kinds of memory devices:
One Parallel Flash (not populated by default)
Two DDR2-SDRAM
One NAND Flash (2Gb, 8 bit bus)
The chip selects NCS0, NCS1 and NCS3 are used for NOR Flash, DDR2-SDRAM and NAND Flash
memories, respectively. Furthermore, a dedicated jumper can disconnect each of the two NCS0 and
NCS3 signals, making them available for other functions.
Table 4-1.
Main Components Associated with the Clock Systems
Quantity
Description
Component assignment
1
Crystal for Internal Clock, 12 MHz
Y1
1
Crystal for RTC Clock, 32.768 kHz
Y2
1
Oscillator for Ethernet Clock RMII, 50 MHz
Y4
1
Crystal for Ethernet Clock MII, 25 MHz (not populated)
Y5
1
Crystal for AC97 Codec Clock, 24.576 MHz
Y3
1
Crystal for TV Encoder Clock, 13 MHz, or
Oscillator for TV Encoder, 13 MHz (not populated)
Y7
Y6
