keyboard/infinity/mbed-infinity/README

   1 mbed fix for Infinity
   2 =====================
   3 Without linker script patch it doesn't place vector table in final binary.
   4 And clock is configured to 48MHz using internal clock reference and FLL multiplication.
   5
   6
   7 mbed/targets/cmsis/TARGET_Freescale/TARGET_K20D50M/system_MK20D5.c
   8     Fix SystemInit: clock setup for internal clock. Inifinity has no external Xtal.
   9
  10 mbed/targets/cmsis/TARGET_Freescale/TARGET_K20D50M/cmsis_nvic.c
  11     Fix NVIC vector address of firmware 0x1000 instead of 0x0
  12
  13 mbed/targets/cmsis/TARGET_Freescale/TARGET_K20D50M/TOOLCHAIN_GCC_ARM/MK20D5.ld
  14     Fix memory map for Infinity bootloader
  15         Flash starts at 0x1000
  16         No flash config bytes sector
  17
  18 USBDevice/USBDevice/USBHAL_KL25Z.cpp
  19     Fix USB clock setup, see below.
  20
  21
  22 2015/01/04  Based on mbed-sdk @2f63fa7d78a26.
  23
  24
  25
  26 Kinetis USB config
  27 ==================
  28 Clock source: Internal reference clock wth FLL
  29     SIM_SOPT[USBSRC] = 1(MCGPLLCLK/MCGFLLCLK)
  30     SIM_SOPT[PLLSEL] = 0(MCGFLLCLK)
  31
  32 Clock dividor:
  33     SIM_CLKDIV2[USBDIV] = 0
  34     SIM_CLKDIV2[USBFAC] = 0
  35
  36 Clock enable:
  37     SIM_SCGC4[USBOTG] = 1
  38
  39
  40
  41 Infinity bootloader change
  42 ==========================
  43 After @2c7542e(2015/01) Infinity bootloader doesn't disable watchdog timer and keyboard firmware has to do it itself.  mbed disables watchdog in startup sequence but unfortunately timer is timed out bofore that.
  44
  45 We have to do that in earlier phase of mbed startup sequence.
  46
  47
  48 mbed starup sequence files:
  49 mbed/targets/cmsis/TARGET_Freescale/TARGET_K20D50M/TOOLCHAIN_GCC_ARM/startup_M20D5.s
  50 mbed/targets/cmsis/TARGET_Freescale/TARGET_K20D50M/system_MK20D5.c
  51
  52 Infinity booloader change commit:
  53 https://github.com/kiibohd/controller/commit/2c7542e2e7f0b8a99edf563dc53164fe1a439483
  54
  55 discussion:
  56 https://geekhack.org/index.php?topic=41989.msg1686616#msg1686616
  57
  58
  59 WORKAROUND
  60 ----------
  61 Call SystemInit early in Reset_Handler.
  62
  63 $ diff -u ../../mbed-sdk/libraries/mbed/targets/cmsis/TARGET_Freescale/TARGET_K20D50M/TOOLCHAIN_GCC_ARM/startup_MK20D5.s mbed-infinity
  64 --- ../../mbed-sdk/libraries/mbed/targets/cmsis/TARGET_Freescale/TARGET_K20D50M/TOOLCHAIN_GCC_ARM/startup_MK20D5.s      2015-03-22 10:33:22.779866000 +0900
  65 +++ mbed-infinity/startup_MK20D5.s      2015-03-22 10:32:56.483866000 +0900
  66 @@ -147,6 +147,8 @@
  67   *      __etext: End of code section, i.e., begin of data sections to copy from.
  68   *      __data_start__/__data_end__: RAM address range that data should be
  69   *      copied to. Both must be aligned to 4 bytes boundary.  */
  70 +    ldr    r0, =SystemInit
  71 +    blx    r0
  72
  73      ldr    r1, =__etext
  74      ldr    r2, =__data_start__
  75 @@ -161,8 +163,6 @@
  76
  77  .Lflash_to_ram_loop_end:
  78
  79 -    ldr    r0, =SystemInit
  80 -    blx    r0
  81      ldr    r0, =_start
  82      bx    r0
  83      .pool