The HAL Port

Name

HAL Port -- Implementation Details

Overview

This documentation explains how the eCos HAL specification has been mapped onto the STM32F4DISCOVERY board hardware and should be read in conjunction with that specification. The STM32F4DISCOVERY platform HAL package complements the Cortex-M architectural HAL and the STM32 variant HAL. It provides functionality which is specific to the target board.

Startup

Following a hard or soft reset the HAL will initialize or reinitialize many of the on-chip peripherals. There is an exception for RAM startup applications which depend on a ROM monitor for certain services.

For ROM and JTAG startup, the HAL will perform additional initialization, programming the various internal registers including the PLL, peripheral clocks and GPIO pins. The details of the early hardware startup may be found in the src/stm32f4dis_misc.c in both hal_system_init and hal_platform_init.

Memory Map

The platform HAL package provides the memory layout information needed to generate the linker script. The key memory locations are as follows:

Internal RAM

This is located at address 0x20000000 of the memory space, and is 128KiB in size. The eCos VSR table occupies the bottom 392-bytes. The virtual vector table starts at 0x20000188 and extends to 0x20000288. For ROM, and JTAG startups, the top CYGNUM_HAL_COMMON_INTERRUPTS_STACK_SIZE bytes are reserved for the interrupt stack. The remainder of internal RAM is available for use by applications.

Internal FLASH

This is located at address 0x08000000 of the memory space and will be mapped to 0x00000000 at reset. This region is 1MiB in size. ROM applications are by default configured to run from this memory.

On-Chip Peripherals

These are accessible at locations 0x40000000 and 0xE0000000 upwards. Descriptions of the contents can be found in the STM32F4 Reference Manual (RM0090).

Linker Scripts

The platform linker scripts define the following symbols:

hal_vsr_table

This defines the location of the VSR table. This is set to 0x20000000 for all startup types, and space for 98 entries is reserved due to the use of the STM32F4 processor.

hal_virtual_vector_table

This defines the location of the virtual vector table used to communicate between an ROM monitor and an eCos application. This is allocated right after the VSR table, at 0x20000188.

hal_interrupt_stack

This defines the location of the interrupt stack. For all startup types this is allocated to the top of available internal SRAM, which is normally 0x20020000.

hal_startup_stack

This defines the location of the startup stack. For all startup types it is initially allocated at the half-way point of the interrupt stack.

Diagnostic LEDs

Four LEDs are fitted on the board for diagnostic purposes:

Platform HAL manifestColourBoard Label
CYGHWR_HAL_STM32F4DIS_LED0OrangeLD3
CYGHWR_HAL_STM32F4DIS_LED1GreenLD4
CYGHWR_HAL_STM32F4DIS_LED2RedLD5
CYGHWR_HAL_STM32F4DIS_LED3BlueLD6

The platform HAL header file at <cyg/hal/plf_io.h> defines the following convenience function to allow the LEDs to be set:

extern void hal_stm32f4dis_led(char c);
    
The lowest 4-bits of the argument c correspond to each of the 4 LEDs (with LED0 as the least significant bit).

The platform HAL will automatically light LED0 when the platform initialisation is complete, however the LEDs are free for application use.

Flash wait states

The STM32F4DISCOVERY platform HAL provides a configuration option to set the number of Flash read wait states to use: CYGNUM_HAL_CORTEXM_STM32_FLASH_WAIT_STATES. It is important to verify and if necessary update this value if changing the CPU clock (HCLK) frequency or CPU voltage. Consult the STM32F40xxx Flash programming manual (PM0081) for appropriate values for different clock speeds or voltages. The default of 5 reflects a supply voltage of 3.3V and HCLK of 168MHz.

Real-time characterization

The tm_basic kernel test gives statistics gathered about the real-time characterization and performance of the kernel. The sample output is shown here for information. The test was built for JTAG startup with optimization flag -O2.

            Startup, main stack : stack used    84 size  1536
             Startup : Idlethread stack used    80 size  1280

eCos Kernel Timings
Notes: all times are in microseconds (.000001) unless otherwise stated

Reading the hardware clock takes 0 'ticks' overhead
... this value will be factored out of all other measurements
Clock interrupt took    4.13 microseconds (4 raw clock ticks)

Testing parameters:
   Clock samples:            32
   Threads:                   6
   Thread switches:         128
   Mutexes:                  32
   Mailboxes:                32
   Semaphores:               32
   Scheduler operations:    128
   Counters:                 32
   Flags:                    32
   Alarms:                   32
   Stack Size:             1096


                                 Confidence
     Ave     Min     Max     Var  Ave  Min  Function
  ======  ======  ======  ====== ========== ========
    4.67    4.00    5.00    0.44   66%  33% Create thread
    1.00    1.00    1.00    0.00  100% 100% Yield thread [all suspended]
    1.00    1.00    1.00    0.00  100% 100% Suspend [suspended] thread
    1.00    1.00    1.00    0.00  100% 100% Resume thread
    1.67    1.00    2.00    0.44   66%  33% Set priority
    0.00    0.00    0.00    0.00  100% 100% Get priority
    2.83    2.00    3.00    0.28   83%  16% Kill [suspended] thread
    1.00    1.00    1.00    0.00  100% 100% Yield [no other] thread
    1.50    1.00    2.00    0.50  100%  50% Resume [suspended low prio] thread
    1.00    1.00    1.00    0.00  100% 100% Resume [runnable low prio] thread
    1.17    1.00    2.00    0.28   83%  83% Suspend [runnable] thread
    1.00    1.00    1.00    0.00  100% 100% Yield [only low prio] thread
    1.00    1.00    1.00    0.00  100% 100% Suspend [runnable->not runnable]
    2.67    2.00    3.00    0.44   66%  33% Kill [runnable] thread
    2.50    2.00    3.00    0.50  100%  50% Destroy [dead] thread
    4.33    4.00    5.00    0.44   66%  66% Destroy [runnable] thread
    5.17    5.00    6.00    0.28   83%  83% Resume [high priority] thread
    1.86    1.00    2.00    0.24   85%  14% Thread switch

    0.21    0.00    1.00    0.33   78%  78% Scheduler lock
    0.80    0.00    1.00    0.31   80%  19% Scheduler unlock [0 threads]
    0.85    0.00    1.00    0.25   85%  14% Scheduler unlock [1 suspended]
    0.84    0.00    1.00    0.27   83%  16% Scheduler unlock [many suspended]
    0.88    0.00    1.00    0.22   87%  12% Scheduler unlock [many low prio]

    0.22    0.00    1.00    0.34   78%  78% Init mutex
    1.19    1.00    2.00    0.30   81%  81% Lock [unlocked] mutex
    1.44    1.00    2.00    0.49   56%  56% Unlock [locked] mutex
    1.13    1.00    2.00    0.22   87%  87% Trylock [unlocked] mutex
    0.97    0.00    1.00    0.06   96%   3% Trylock [locked] mutex
    0.28    0.00    1.00    0.40   71%  71% Destroy mutex
    6.00    6.00    6.00    0.00  100% 100% Unlock/Lock mutex

    0.44    0.00    1.00    0.49   56%  56% Create mbox
    0.19    0.00    1.00    0.30   81%  81% Peek [empty] mbox
    1.19    1.00    2.00    0.30   81%  81% Put [first] mbox
    0.16    0.00    1.00    0.26   84%  84% Peek [1 msg] mbox
    1.19    1.00    2.00    0.30   81%  81% Put [second] mbox
    0.22    0.00    1.00    0.34   78%  78% Peek [2 msgs] mbox
    1.28    1.00    2.00    0.40   71%  71% Get [first] mbox
    1.19    1.00    2.00    0.30   81%  81% Get [second] mbox
    1.03    1.00    2.00    0.06   96%  96% Tryput [first] mbox
    1.03    1.00    2.00    0.06   96%  96% Peek item [non-empty] mbox
    1.16    1.00    2.00    0.26   84%  84% Tryget [non-empty] mbox
    1.00    1.00    1.00    0.00  100% 100% Peek item [empty] mbox
    1.00    1.00    1.00    0.00  100% 100% Tryget [empty] mbox
    0.22    0.00    1.00    0.34   78%  78% Waiting to get mbox
    0.22    0.00    1.00    0.34   78%  78% Waiting to put mbox
    0.44    0.00    1.00    0.49   56%  56% Delete mbox
    3.84    3.00    4.00    0.26   84%  15% Put/Get mbox

    0.28    0.00    1.00    0.40   71%  71% Init semaphore
    0.97    0.00    1.00    0.06   96%   3% Post [0] semaphore
    1.00    1.00    1.00    0.00  100% 100% Wait [1] semaphore
    0.97    0.00    1.00    0.06   96%   3% Trywait [0] semaphore
    1.00    1.00    1.00    0.00  100% 100% Trywait [1] semaphore
    0.25    0.00    1.00    0.38   75%  75% Peek semaphore
    0.41    0.00    1.00    0.48   59%  59% Destroy semaphore
    3.78    3.00    4.00    0.34   78%  21% Post/Wait semaphore

    0.47    0.00    1.00    0.50   53%  53% Create counter
    0.34    0.00    1.00    0.45   65%  65% Get counter value
    0.16    0.00    1.00    0.26   84%  84% Set counter value
    1.09    1.00    2.00    0.17   90%  90% Tick counter
    0.34    0.00    1.00    0.45   65%  65% Delete counter

    0.31    0.00    1.00    0.43   68%  68% Init flag
    1.09    1.00    2.00    0.17   90%  90% Destroy flag
    0.97    0.00    1.00    0.06   96%   3% Mask bits in flag
    1.00    1.00    1.00    0.00  100% 100% Set bits in flag [no waiters]
    1.56    1.00    2.00    0.49   56%  43% Wait for flag [AND]
    1.50    1.00    2.00    0.50  100%  50% Wait for flag [OR]
    1.56    1.00    2.00    0.49   56%  43% Wait for flag [AND/CLR]
    1.50    1.00    2.00    0.50  100%  50% Wait for flag [OR/CLR]
    0.25    0.00    1.00    0.38   75%  75% Peek on flag

    0.63    0.00    1.00    0.47   62%  37% Create alarm
    1.63    1.00    2.00    0.47   62%  37% Initialize alarm
    0.97    0.00    1.00    0.06   96%   3% Disable alarm
    1.50    1.00    2.00    0.50  100%  50% Enable alarm
    1.06    1.00    2.00    0.12   93%  93% Delete alarm
    1.25    1.00    2.00    0.38   75%  75% Tick counter [1 alarm]
    8.66    8.00    9.00    0.45   65%  34% Tick counter [many alarms]
    2.22    2.00    3.00    0.34   78%  78% Tick & fire counter [1 alarm]
   39.91   39.00   40.00    0.17   90%   9% Tick & fire counters [>1 together]
    9.59    9.00   10.00    0.48   59%  40% Tick & fire counters [>1 separately]
    4.00    4.00    4.00    0.00  100% 100% Alarm latency [0 threads]
    3.25    3.00    4.00    0.38   75%  75% Alarm latency [2 threads]
    3.22    3.00    4.00    0.34   78%  78% Alarm latency [many threads]
    7.01    7.00    8.00    0.01   99%  99% Alarm -> thread resume latency

  224    220     228  (main stack:   877)  Thread stack used (1096 total)
           All done, main stack : stack used   877 size  1536
            All done : Idlethread stack used   168 size  1280

Timing complete - 27850 ms total

PASS:<Basic timing OK>
EXIT:<done>
   
2017-02-09
Documentation license for this page: eCosPro License