DocID027351 Rev 3
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UM1855
Hardware layout and configuration
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2.6.2 Bootloader
limitations
Boot from system Flash memory results in executing
bootloader
code stored in the system
Flash memory protected against write and erase. This allows in-system programming (ISP),
that is, flashing the MCU user Flash memory. It also allows writing data into RAM. The data
come in via one of communication interfaces such as USART, SPI, I²C bus, USB or CAN.
Bootloader version can be identified by reading Bootloader ID at the address 0x1FFF6FFE.
The STM32L476ZGT6 part soldered on the STM32L476G-EVAL main board is marked with
a date code corresponding to its date of manufacture. STM32L476ZGT6 parts with the date
code prior or equal to week 22 of 2015 are fitted with
bootloader V 9.0
affected by the
limitations to be worked around, as described hereunder. Parts with the date code starting
week 23 of 2015 contain bootloader V9.2 in which the limitations no longer exist.
To locate the visual date code information on the STM32L476ZGT6 package, refer to its
datasheet (DS10198) available on
www.st.com
, section Package Information. Date code
related portion of the package marking takes Y WW format, where Y is the last digit of the
year and WW is the week. For example, a part manufactured in week 23 of 2015 bares the
date code 5 23.
Bootloader ID of the bootloader V 9.0 is 0x90.
The following limitations exist in the bootloader V 9.0:
1.
RAM data get corrupted when written via USART/SPI/I2C/USB interface
Description:
Data write operation into RAM space via USART, SPI, I²C bus or USB results in wrong
or no data written.
Workaround:
To correct the issue of wrong write into RAM, download STSW-STM32158 bootloader
V 9.0 patch package from
www.st.com
and load "Bootloader V9.0 SRAM patch" to the
MCU, following the information in readme.txt file available in the package.
2.
User Flash memory data get corrupted when written via CAN interface
Description:
Data write operation into user Flash memory space via CAN interface results in wrong
or no data written.
Workaround:
To correct the issue of wrong write into Flash memory, download STSW-STM32158
bootloader V 0.9 patch package from
www.st.com
and load "Bootloader V9.0 CAN
patch" to the MCU, following the information in readme.txt file available in the package.
2.7 Audio
A codec connected to SAI interface of STM32L476ZGT6 supports TDM feature of the SAI
port. TDM feature offers to STM32L476ZGT6 the capability to stream two independent
stereo audio channels to two separate stereo analog audio outputs, simultaneously.
There are two digital microphones on board of STM32L476G-EVAL.
