at91sam9260-cj ATMEL Corporation, at91sam9260-cj Datasheet - Page 77

• Manufacturer Part Number: at91sam9260-cj
• Description: At91 Arm Thumb Microcontrollers
• Manufacturer: ATMEL Corporation

13.3
6221G–ATARM–31-Jan-08
Device Initialization
Initialization follows the steps described below:
Table 13-1.
Note:
Table 13-2.
Note:
Table 13-3.
Note:
Boot on DBGU
Boot on USB
Boot on DBGU
Boot on USB
3.0
4.433619
6.144
7.864320
12.0
16.0
1. FIQ Initialization
2. Stack setup for ARM supervisor mode
3. External Clock Detection
4. Switch Master Clock on Main Oscillator
5. C variable initialization
6. Main oscillator frequency detection if no external clock detected
7. PLL setup: PLLB is initialized to generate a 48 MHz clock necessary to use the USB
Device. A register located in the Power Management Controller (PMC) determines the
frequency of the main oscillator and thus the correct factor for the PLLB.
a. If Internal RC Oscillator is used (OSCSEL = 0) and Main Oscillator is active,
b. If Internal RC Oscillator is used (OSCSEL = 0) and Main Oscillator is bypassed,
c. If an external 32768 Hz Oscillator is used (OSCSEL = 1),
Any other crystal can be used but it prevents using the USB.
Any other input frequency can be used but it prevents using the USB.
Booting either on USB or on DBGU is possible with any of these crystals.
13-1
RC oscillator.
Table 13-2
ing main oscillator.
crystals supported by the Boot Program.
Reduced Crystal Table (MHz) OSCSEL = 0
Input Frequencies Supported by Software Auto-detection (MHz) OSCSEL = 0
Large Crystal Table (MHz) OSCSEL = 1
defines the crystals supported by the Boot Program when using the internal
Yes
Yes
3.0
3.2768
16.367667
4.9152
6.4
8.0
12.288
defines the frequencies supported by the Boot Program when bypass-
1.0
Yes
Yes
2.0
Yes
Yes
6.0
Yes
Yes
3.6864
5.0
6.5536
9.8304
13.56
17.734470
6.0
Yes
Yes
12.0
Yes
Yes
18.432
Yes
Yes
3.84
5.24288
7.159090
10.0
14.31818
18.432
25.0
Yes
Yes
Table 13-3
AT91SAM9260
50.0
Yes
Yes
Other
Yes
No
4.0
6.0
7.3728
11.05920
14.7456
20.0
defines the
Table
Other
Yes
No
77