SAM3SD8C Atmel Corporation, SAM3SD8C Datasheet - Page 353

• Manufacturer Part Number: SAM3SD8C
• Manufacturer: Atmel Corporation

21. SAM3S8/SD8 Boot Program
21.1
21.2
21.3
Figure 21-1. Boot Program Algorithm Flow Diagram
11090A–ATARM–10-Feb-12
11090A–ATARM–10-Feb-12
Description
Hardware and Software Constraints
Flow Diagram
The SAM-BA Boot Program integrates an array of programs permitting download and/or upload
into the different memories of the product.
Note:
Table 21-1.
The Boot Program implements the algorithm in
The SAM-BA Boot program seeks to detect a source clock either from the embedded main oscil-
lator with external crystal (main oscillator enabled) or from a supported frequency signal applied
to the XIN pin (Main oscillator in bypass mode).
If a clock is found from the two possible sources above, the boot program checks to verify that
the frequency is one of the supported external frequencies. If the frequency is one of the sup-
ported external frequencies, USB activation is allowed, else (no clock or frequency other than
one of the supported external frequencies), the internal 12 MHz RC oscillator is used as main
clock and USB clock is not allowed due to frequency drift of the 12 MHz RC oscillator.
Device
Setup
Peripheral
UART0
UART0
• SAM-BA Boot uses the first 2048 bytes of the SRAM for variables and stacks. The remaining
• USB Requirements:
• UART0 requirements: None
available size can be used for user's code.
11,289 MHz
12,000 MHz
16,000 MHz
18,432 MHz
– External Crystal or External Clock
1. Must be 2500 ppm and 1.8V Square Wave Signal.
Pins Driven during Boot Program Execution
Run SAM-BA Monitor
USB Enumeration
Successful ?
Yes
Pin
URXD0
UTXD0
(1)
No
with frequency of:
Figure
Run SAM-BA Monitor
Character # received
No
from UART0?
21-1.
Yes
SAM3S8/SD8
SAM3S8/SD8
PIO Line
PA10
PA9
353
353