近期使用了ST公司的STM32單片機，遇到了奇怪的現象：每個單片機只能下載一次程序，之后的每次操作都會出現Flash寫入錯誤，更換4，5次單片機也是如此，如下圖。

窗口中的打印信息為

JLink info:
------------
DLL: V4.40c, compiled Jan 24 2012 09:30:33
Firmware: J-Link ARM V8 compiled Dec  6 2011 18:57:44
Hardware: V8.00
S/N : 20100214 
Feature(s) : RDI,FlashDL,FlashBP,JFlash,GDBFull 
 
* JLink Info: Found SWD-DP with ID 0x1BA01477
* JLink Info: TPIU fitted.
* JLink Info:   FPUnit: 6 code (BP) slots and 2 literal slots
* JLink Info: Found Cortex-M3 r1p1, Little endian.
ROMTableAddr = 0xE00FF003
* JLink Info: Found SWD-DP with ID 0x1BA01477
* JLink Info: TPIU fitted.
* JLink Info:   FPUnit: 6 code (BP) slots and 2 literal slots
* JLink Info: Found Cortex-M3 r1p1, Little endian.
 
Target info:
------------
Device: STM32F103T8
VTarget = 3.028V
State of Pins: 
TCK: 0, TDI: 0, TDO: 0, TMS: 0, TRES: 1, TRST: 1
Hardware-Breakpoints: 6
Software-Breakpoints: 8192
Watchpoints:          4
JTAG speed: 2000 kHz
 
Erase Done.
Programming Failed!

筆者使用的下載方式是SWD，從打印信息中可以看到，JLink成功地擦除了單片機的Flash，但寫入失敗。然而，在這款產品的第一版中，并沒有出現這樣的問題。較大的區別是，第一版所用型號為STM32F103C8T6，第二版為了縮小尺寸選用了STM32F103T8U6。查看Datasheet，認為這里兩款芯片除了封裝尺寸，IO數目不同以外，在配置上并沒有什么差異。

嘗試診斷問題，發現Flash下載配置選項似乎不正常，如下圖：

根據已有的產品開發經驗，如果Flash擦除不完整，很容易出現問題。于是勾選“Erase Full Chip”選項，如下圖。

再次下載程序，終于成功了，窗口中出現了正確的打印信息

JLink info:
------------
DLL: V4.40c, compiled Jan 24 2012 09:30:33
Firmware: J-Link ARM V8 compiled Dec  6 2011 18:57:44
Hardware: V8.00
S/N : 20100214 
Feature(s) : RDI,FlashDL,FlashBP,JFlash,GDBFull 
 
* JLink Info: Found SWD-DP with ID 0x1BA01477
* JLink Info: TPIU fitted.
* JLink Info:   FPUnit: 6 code (BP) slots and 2 literal slots
* JLink Info: Found Cortex-M3 r1p1, Little endian.
ROMTableAddr = 0xE00FF003
* JLink Info: Found SWD-DP with ID 0x1BA01477
* JLink Info: TPIU fitted.
* JLink Info:   FPUnit: 6 code (BP) slots and 2 literal slots
* JLink Info: Found Cortex-M3 r1p1, Little endian.
 
Target info:
------------
Device: STM32F103T8
VTarget = 3.028V
State of Pins: 
TCK: 0, TDI: 0, TDO: 0, TMS: 0, TRES: 1, TRST: 1
Hardware-Breakpoints: 6
Software-Breakpoints: 8192
Watchpoints:          4
JTAG speed: 2000 kHz
 
Full Chip Erase Done.
Programming Done.
Verify OK.