AT91SAM7X128 Atmel, AT91SAM7X128 Datasheet - Page 135

• Manufacturer Part Number: AT91SAM7X128
• Description: MCU 32-Bit 91S ARM7TDMI RISC 128KB Flash 1.8V/3.3V 100-Pin LQFP
• Manufacturer: Atmel

Specifications of AT91SAM7X128

• Package: 100LQFP
• Device Core: ARM7TDMI
• Family Name: 91S
• Maximum Speed: 55 MHz
• Ram Size: 32 KB
• Program Memory Size: 128 KB
• Operating Supply Voltage: 1.8|3.3 V
• Data Bus Width: 32 Bit
• Program Memory Type: Flash
• Number Of Programmable I/os: 62
• Interface Type: CAN/Ethernet/SPI/I2S/TWI/USART/USB
• On-chip Adc: 8-chx10-bit
• Operating Temperature: -40 to 85 °C
• Number Of Timers: 3

21. AT91SAM Boot Program
21.1
21.2
21.3
6120H–ATARM–17-Feb-09
Overview
Flow Diagram
Device Initialization
The Boot Program integrates different programs permitting download and/or upload into the dif-
ferent memories of the product.
First, it initializes the Debug Unit serial port (DBGU) and the USB Device Port.
SAM-BA
DBGU serial port.
The Boot Program implements the algorithm in
Figure 21-1. Boot Program Algorithm Flow Diagram
Initialization follows the steps described below:
1. FIQ initialization
1. Stack setup for ARM supervisor mode
2. Setup the Embedded Flash Controller
3. External Clock detection
4. Main oscillator frequency detection if no external clock detected
5. Switch Master Clock on Main Oscillator
6. Copy code into SRAM
7. C variable initialization
8. PLL setup: PLL is initialized to generate a 48 MHz clock necessary to use the USB
9. Disable of the Watchdog and enable of the user reset
10. Initialization of the USB Device Port
11. Jump to SAM-BA Boot sequence (see
Device
®
Boot is then executed. It waits for transactions either on the USB device, or on the
Device
Setup
AT91SAM7X512/256/128 Preliminary
Run SAM-BA Boot
USB Enumeration
Successful ?
Yes
“SAM-BA Boot” on page
Figure
21-1.
No
Sequence Successful ?
Run SAM-BA Boot
No
AutoBaudrate
136)
Yes
135