Atmel SAM4S Series, Preliminary Data Sheet

Page: 393 / 1163

393
11100B–ATARM–31-Jul-12
SAM4S Series [Preliminary]
23. SAM4S Boot Program
23.1 Description
The SAM-BA Boot Program integrates an array of programs permitting download and/or upload
into the different memories of the product.
23.2 Hardware and Software Constraints
• SAM-BA Boot uses the first 2048 bytes of the SRAM for variables and stacks. The remaining
available size can be used for user's code.
• USB Requirements:
– External Crystal or External Clock
(1)
with frequency of:
11,289 MHz
12,000 MHz
16,000 MHz
18,432 MHz
• UART0 requirements: None
Note: 1. Must be 2500 ppm and 1.2V Square Wave Signal.
23.3 Flow Diagram
The Boot Program implements the algorithm in Figure 23-1 .
Figure 23-1. Boot Program Algorithm Flow Diagram
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).
Table 23-1. Pins Driven during Boot Program Execution
Peripheral Pin PIO Line
UART0 URXD0 PA9
UART0 UTXD0 PA10
Device
Setup
Character # received
from UART0?
Run SAM-BA Monitor
USB Enumeration
Successful ?
Yes
Run SAM-BA Monitor
Yes
No
No