at91rm3400 ATMEL Corporation, at91rm3400 Datasheet - Page 48

• Manufacturer Part Number: at91rm3400
• Description: Atmel Advanced At91 Arm Microcontroller
• Manufacturer: ATMEL Corporation

Bootloader
Sequence
Device Initialization
Download Procedure
48
AT91RM3400
The Boot Program performs device initialization followed by the download procedure. If unsuc-
cessful, the upload is done via the USB or debug serial port.
Initialization follows the steps described below:
1. PLL setup
Table 13. Crystals Supported by Software Auto-detection (MHz)
2. Stacks setup for each ARM mode
3. Main oscillator frequency detection
4. Interrupt controller setup
5. C variables initialization
6. Branch main function
The download procedure checks for a valid boot on several devices. The first device checked
is a serial DataFlash connected to the NPCS0 of the SPI, followed by the serial EEPROM con-
nected to the TWI and by an 8-bit parallel memory connected on NCS0 of the External Bus
Interface (if EBI is implemented in the product).
3.0
4.433619
6.144
7.864320
12.0
16.0
25.0
–
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.
Table 13 defines the crystals supported by the Boot Program.
3.2768
4.9152
6.4
8.0
12.288
17.734470
28.224
3.6864
5.0
6.5536
9.8304
13.56
18.432
32.0
3.84
5.24288
7.159090
10.0
14.31818
20.0
33.0
4.0
6.0
7.3728
11.05920
14.7456
24.0
1790A–ATARM–11/03