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

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

>>>>> "Uwe" == Uwe Bonnes <bo...@el...> writes:

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

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

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

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

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

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

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

More facts: If I remove the WFI() (Wait for interrupt) call in the idle
thread, reading the Flash Size register works as expected. 
-- 
Uwe Bonnes                bo...@el...

Institut fuer Kernphysik  Schlossgartenstrasse 9  64289 Darmstadt
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