初识AT91SAM7S64芯片
0赞第一次使用AT91SAM7S系列的芯片，直接用Jlink去写，发现写不进去，
后来网友告诉说是TST信号错了，后来就仔细查了这个系列的芯片boot相关的信息，作了一个全面的了解，顺便在这里作下笔
SAM－BA 全称： SAM - Boot Assistant (SAM-BA?)
系统恢复程序（System Recovery Procedure)
1，目标板下电，
2，重新对目标板上电之前请确保TST，PA0/PGMEN0，PA1/PGMEN1，PA2/PGMEN2 信号已经置位（参见上面的表格），由于PA0/PGMEN0，PA1/PGMEN1，PA2/PGMEN2 内置上拉电阻，且复位后上拉电阻使能，而TST复位后为下拉电阻使能，故只要将TST 信号上拉即可，对于AT91SAM7S-EK，短接JP5 即可，译者注：步骤2 假设TST，PA0-2 均未接外部上拉或者下拉电阻，如果有接则请自行保证信号的电平符合上表，
3，目标板上电，并请等待10 秒钟，
4，下电，将TST 信号悬空，对于AT91SAM7S-EK 拔掉JP5 短路帽即可，
5，上电，此时目标板上的SAM-BA Boot 应用程序已经运行于FLASH 并等
待来自于USB 或者DBGU 的主连接（PC）
英文原文
AT91SAM7S Series
INFORMATION:
The following table gives you ROMed boot-up applications according to the pin setting after a power-up or a reset.
| Pin Name |
Level
|
Level
|
Default State after reset
|
| TST |
1
|
1
|
Pull-down
|
| PA0/PGMEN0 |
1
|
1
|
Pull-up
|
| PA1/PGMEN1 |
1
|
1
|
Pull-up
|
| PA2/PGMEN2 |
0
|
1
|
Pull-up
|
|
|
|||
| Boot up Application -> |
FFPI
|
SAM-BA Boot |
|
Other pin setting about TST, PA[0,1,2]/PGMEN|0,1,2] are reserved.
SYSTEM RECOVERY PROCEDURE:
1.Shut down the board,
2.Before to power up the board, the TST, PA0/PGMEN0, PA1/PGMEN1, and PA2/PGMEN2 signals must be set (see the table on the left which gives you an overview about these pins). On the AT91SAM7S-EK evaluation board, put only the JP5 jumper to set the TST signal (by default, others signal are set thanks to the embedded pull-up resistors).
3.Power up the board and wait 10 secondes,
4.Shut down the board and remove the JP5 jumper,
5.Power up the board: The board is now working with the SAM-BA Boot application from the flash and waiting connection through USB port.
IMPORTANT: THIS SYSTEM RECOVERY PROCEDURE CANNOT BE EXECUTED IF THE FLASH SECURITY BIT IS SET.
NFORMATION: What has the Recovery Procedure Performed ?
The recovery procedure has:
- Forced the AT91SAM7S to boot from its internal ROM (first power up with TST = 1),
- Unlocked the fisrt two regions,
- Erased the first two regions (8 KBytes only),
- Copied the SAM-BA Boot to the first 4.5 kbytes Flash memory area,
- Locked these regions,
- Start the SAM-BA Boot (second power up with TST = 0).
At this level, the target is working out of internal Flash with SAM-BA Boot and waiting serial connection from SAM-PRO through its USB socket.
SAM－BA 全称： SAM - Boot Assistant (SAM-BA?)
系统恢复程序（System Recovery Procedure）
1，目标板下电，
2，重新对目标板上电之前请确保TST按下（中间的那个绿色按钮）
3，目标板上电，并请等待10 秒钟，
4，下电，将TST 信号悬空，
5，上电，此时目标板上的SAM-BA Boot 应用程序已经运行于FLASH 并等待来自于USB 或者DBGU 的主连接（PC）
然后即可使用sam－ba下载固件了。
