FAQ STM32MPUs: How to validate the STM32MPU-DRAM connection on the PCB with DDR test suite
After the PCB is released, it is possible to check whether the hardware connection between the DRAM and the STM32 microprocessor unit (MPU) DDR interface is functional. The STM32 DDRFW-UTILS tool helps validate that the connection is functional.
ST helps PCB designers by providing application notes with layout recommendations and layout examples. For more information, see STM32MPx resource for PCB design signal integrity
1. DDR test suite for the PCB validation
In most designs, the DDR test suite passes when the designer follows the ST application note on layout constraints and when the schematic and layout contain no errors.
Passing the DDR test suite is the main criterion for validating the design across the full STM32 microprocessor unit (MPU) temperature range with DDR3, DDR3L, DDR4, or LPDDR4 memory types.
During the bring-up phase, test the design with the STM32DDRFW-UTIL test suite.
2. Manual DDR PHY Tuning is deprecated
Manual DDR PHY tuning on different boards is not necessary. DDR PHY tuning is automatic at boot time. Since Ecosystem 4.0, the user must use automatic DDR PHY built-in tuning by not using the st,phy-cal property in the TF-A device tree. This property is deprecated because DDR PHY built-in tuning is always enabled in the 4.x ecosystem release.
For more information, refer to the ST Wiki:
ST Wiki: DDRCTRL and DDRPHYC device tree configuration.
3. Where to get the DDR test suite binary
DDR tests are available in the STM32DDRFW-UTIL firmware, which must be compiled in an STM32CubeIDE project. The DDR test suite allows memory testing with a set of DDR controller settings. After the settings are validated, compile them in TF-A.
The DDR test binary is loaded by JTAG on the microprocessor unit (MPU) in engineering boot mode from STM32CubeIDE. It can also be loaded with the STM32CubeProgrammer command-line interface (CLI). Control the tests by writing commands on the Linux UART console. Alternatively, start the test from the STM32CubeMX DDR test suite graphical user interface (GUI). DDR tests can run on Windows or Linux operating systems.
4. Where to get the DDR test documentation
Under STM32DDRFW-UTIL - stm32mpu, the GitHub project and the README.txt file provide instructions to run the test.
UM1718 in STM32CubeMX shows device tree file generation to configure the STM32 microprocessor unit (MPU) DDR controller. It also provides instructions to run the DDR tests. Accurate details about the DDR controller of STM32MP1 devices and STM32MP2 devices, and about STM32CubeMX dynamic random-access memory (DRAM) configuration parameters, are available in AN5168 for the STM32MP1 family and AN5723 for the STM32MP2 family.