答案

访问 Silicon Labs RoHS 信息页面，通过芯片型号搜索并下载指定芯片的质量报告，要求先通过www.silabs.com 注册一个账户并登录才能查看。

http://www.silabs.com/support/quality/Pages/RoHSInformation.aspx

1. 登录账户之后，点击 Corporate, Product, Environment 按钮，输入芯片型号搜索。

2. 在搜索结果中选择正确的芯片型号，点击右边箭头继续。

3. 选择 Quality Information -> Documents & Reports -> Qual Report，然后点击右边箭头继续。

4. 点击 Link1 下载芯片的质量报告。

Answer

We do not have characterization of the internal references by themselves, but the accuracy is reflected in the peripheral characterization. For example, the error numbers of the ADC include the inaccuracies of the internal reference.

The latest EFM32LG datasheet added some characterization data for internal VREF voltage.

Answer

All devices after Feb 28, 2013 contain the device ID as specified in the reference manual. Prior to this time, the device ID register contains a unique ID.

Answer

On many EFM32 STKs, some I2C locations share pins with other hardware on the board. For example, the EFM32TG STK has both an LED on PD7 and a phototransistor on PD6, both of which will interfere with I2C traffic if these pins are used for I2C. If these pins must be used for I2C, these two components should be removed from the STK.

Answer

All functions are placed in sections, and the flash and RAM addresses of these sections can be viewed in the .map file.

By default, Studio will generate a .map file in the debug or release folder after a project has been built successfully.

For example, if we build the STK3800_blink project in debug mode, the linker will generate a STK3800_blink.map file in the Debug folder (ie GNU ARM v4.8.3 - Debug).

The map file is organized into several sections:

1. Archive member

2. Allocating common symbols

3. Discarded input section - sections that the linker discarded since they aren't used (ie a function isn't called and variables are unused/optimized away).

4. Memory Configuration - provides a summary of the memory regions configured in the linker script (.ld file).

5. Linker script and memory map - shows a list of object files and library files included in the build and a list of sections showing object/function memory locations and size. For example, here we see that the section .text.Delay is located in flash at 0x00000268 and is 0x2c bytes in length.  In this case, the function Delay() is automatically placed in a .text section with the function name appended to the end.

Similarly, variables stored in RAM are normally stored in .data sections.

Answer

Placing a function in a specific memory region such as an address range in flash or RAM requires modifications to the linker script and source files to specify a memory region, memory section, and section attribute.

For example, to locate a function, Delay(), in STK3800_blink (EFM32WG), perform the following steps:

1. Create a new MCU project using the EFM32WG STK example, STK3800_blink.

2. Create a custom linker script using the auto-generated debug or release .ld file as a template.

3. Edit the customer linker script as follows:

a. Create a new memory region called MY_REGION, which starts in flash at the 128 KB boundary (0x20000), and is 128 KB in length.  The region is specified as readable and executable since flash cannot be written directly.  We also reduce the length of the FLASH region to account for this new region.

MEMORY
{
	FLASH (rx) : ORIGIN = 0x0, LENGTH = 128K
	RAM (rwx) : ORIGIN = 0x20000000, LENGTH = 32k
	MY_MEMORY (rx) : ORIGIN = 0x20000, LENGTH = 128k
}

b. Create a new section called .mysection, which places all objects with a section attribute containing the string .mysection in MY_REGION. We can add this section just after the __etext = .; line so we don't affect the FLASH overflow boundary check. To add overflow checking to make sure that the MY_REGION memory doesn't overflow, we can create pointers to the start and end of the .mysection section by adding __mysection_start__ and __mysection_end__ pointers. The dot (.) symbol indicates the current address during the linking phase.

  ...

  __etext = .;

  .mysection :
  {
    . = ALIGN(4);
    __mysection_start__ = .;
	*(.mysection*)
    __mysection_end__ = .;
  } > MY_MEMORY

c. To make sure we don't overflow the MY_MEMORY region, we can add an assert at the end of the linker script to calculate the used length of the MY_MEMORY region and make sure it's less than the total length of the region:

  ...
  
  /* Check if FLASH usage exceeds FLASH size */
  ASSERT( LENGTH(FLASH) >= (__etext + SIZEOF(.data)), "FLASH memory overflowed !")
  
  /* Check if MY_MEMORY usage exceeds MY_MEMORY size */
  ASSERT( LENGTH(MY_MEMORY) >= (__mysection_end__ - __mysection_start__), "MY_MEMORY memory overflowed !")

 4. Add the __section__ attribute to the function in blink.c, specifying which section the function belongs to:

#define LOCATE_FUNC  __attribute__((__section__(".mysection")))

/**************************************************************************//**
 * @brief Delays number of msTick Systicks (typically 1 ms)
 * @param dlyTicks Number of ticks to delay
 *****************************************************************************/
void LOCATE_FUNC Delay(uint32_t dlyTicks)
{
  uint32_t curTicks;

  curTicks = msTicks;
  while ((msTicks - curTicks) < dlyTicks) ;
}

5. Clean and build the project again to use the updated linker script.

6. Open the .map file to verify that the Delay() function is indeed located at 0x20000.

For more information on how to use a custom GCC linker script in Simplicity Studio, see Using a custom linker script in Simplicity IDE.

For more information on how to read the GCC map file to determine the location of a function or section, see Interpreting the GCC map file in Simplicity IDE.