[OpenOCD-devel] STM32: Why does reading flash size fail after hard reset?

[Uwe B. <bo...@el...>]

Hello,

starting openocd after a hardware reset for the first time, the sequence

retval = target_read_u32(target, DBGMCU_IDCODE, &device_id);
retval = target_read_u16(target, FLASH_SIZE_REG, &flash_size_in_kb);

only succeeds for DBGMCU_IDCODE (0xE0042000), while the read for
FLASH_SIZE_REG (0x1FFF75E0) fails. This happens with STLINK and
Segger STLINK:

jaylink: Failed to retrieve serial number: LIBUSB_ERROR_IO.
Info : No device selected, using first device.
Info : J-Link STLink V21 compiled Apr 15 2016 10:47:22
Info : Hardware version: 1.00
Info : VTarget = 3.300 V
Info : clock speed 2000 kHz
Info : SWD DPIDR 0x2ba01477
Info : stm32f4x.cpu: hardware has 6 breakpoints, 4 watchpoints
Info : accepting 'gdb' connection on tcp/3333
Info : device id = 0x10006421
Info : flash size = 8192kbytes

Now some action that halts the cpu like "halt" is executed and openocd is
user terminated.

On the next start, flash size register is read right:

Info : SWD DPIDR 0x2ba01477
Info : stm32f4x.cpu: hardware has 6 breakpoints, 4 watchpoints
Info : accepting 'gdb' connection on tcp/3333
Info : device id = 0x10006421
Info : flash size = 512kbytes

Any idea what is going wrong here?

Thanks
-- 
Uwe Bonnes                bo...@el...

Institut fuer Kernphysik  Schlossgartenstrasse 9  64289 Darmstadt
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