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user/bsps/imxrt: Add new BSP variant
Add information about the new i.MXRT1166 BSP. Rework some parts that have been changed during or as preparation for that variant: * The BSP now adapts to the Chip variant. It's no longer necessary to overwrite the PLL settings in an application. * Improve documentation on how to adapt to different boards. * Add Update the i.MXRT chapter so that it represents the new i.MXRT1166 BSP. * Add information about mcux-sdk and how to handle it.
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Christian Mauderer
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@ -6,14 +6,17 @@
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imxrt (NXP i.MXRT)
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==================
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This BSP offers only one variant, the `imxrt1052`. This variant supports the
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i.MXRT 1052 processor on a IMXRT1050-EVKB (tested with rev A1). You can also
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configure it to work with custom boards.
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This BSP offers multiple variants. The `imxrt1052` supports the i.MXRT 1052
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processor on a IMXRT1050-EVKB (tested with rev A1). Some possibilities to adapt
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it to a custom board are described below.
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NOTE: The IMXRT1050-EVKB has an backlight controller that must not be enabled
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without load. Make sure to either attach a load, disable it by software or
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disable it by removing the 0-Ohm resistor on it's input.
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The `imxrt1166-cm7-saltshaker` supports an application specific board. Adapting
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it to another i.MXRT1166 based board works similar like for the `imxrt1052` BSP.
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Build Configuration Options
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---------------------------
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@ -22,8 +25,24 @@ for that. You can generate a default set of options with::
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./waf bspdefaults --rtems-bsps=arm/imxrt1052 > config.ini
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Boot Process
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------------
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Adapting to a different board
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-----------------------------
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This is only a short overview for the most important steps to adapt the BSP to
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another board. Details for most steps follow further below.
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#. The device tree has to be adapted to fit the target hardware.
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#. A matching clock configuration is necessary (simplest method is to generate
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it with the NXP PinMux tool)
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#. The `dcd_data` has to be adapted. That is used for example to initialize
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SDRAM.
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#. `imxrt_flexspi_config` has to be adapted to match the Flash connected to
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FlexSPI (if that is used).
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#. `BOARD_InitDEBUG_UARTPins` should be adapted to match the used system
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console.
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Boot Process of IMXRT1050-EVKB
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------------------------------
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There are two possible boot processes supported:
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@ -82,18 +101,19 @@ ones that need different values):
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You can find the default definitions in `bsps/arm/imxrt/start/flash-*.c`. Take a
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look at the `i.MX RT1050 Processor Reference Manual, Rev. 4, 12/2019` chapter
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`9.7 Program image` for details about the contents.
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`9.7 Program image` or `i.MX RT1166 Processor Reference Manual, Rev. 0, 05/2021`
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chapter `10.7 Program image` for details about the contents.
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FDT
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---
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The BSP uses a FDT based initialization. The FDT is linked into the application.
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You can find the default FDT used in the BSP in
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`bsps/arm/imxrt/dts/imxrt1050-evkb.dts`. The FDT is split up into two parts. The
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core part is put into an `dtsi` file and is installed together with normal
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headers into `${PREFIX}/arm-rtems@rtems-ver-major@/imxrt1052/lib/include`. You
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can use that to create your own device tree based on that. Basically use
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something like::
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You can find the default FDT used in the BSPs in `bsps/arm/imxrt/dts`. The FDT
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is split up into two parts. The controller specific part is put into an `dtsi`
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file. The board specific one is in the dts file. Both are installed together
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with normal headers into
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`${PREFIX}/arm-rtems@rtems-ver-major@/${BSP}/lib/include`. You can use that to
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create your own device tree based on that. Basically use something like::
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/dts-v1/;
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@ -137,26 +157,6 @@ You'll get a C file which defines the `imxrt_dtb` array. Make sure that your new
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C file is compiled and linked into the application. It will overwrite the
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existing definition of the `imxrt_dtb` in RTEMS.
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PLL Settings
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------------
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The commercial variant of the i.MXRT1052 on the evaluation board allows a clock
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up to 600MHz for the ARM core. For some industrial variants only up to 528MHz
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are specified. To make it possible to adapt to these variants the application
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can overwrite the following constant:
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.. code-block:: c
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#include "fsl_clock_config.h"
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const clock_arm_pll_config_t armPllConfig_BOARD_BootClockRUN = {
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.loopDivider = 100,
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.src = 0,
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};
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With the default configuration of a 24MHz oscillator, the loopDivider has to be
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88 for the 528MHz.
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Clock Driver
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------------
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@ -225,13 +225,58 @@ the SDK. But please note that they are not tested and maybe won't work out of
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the box. Everything that works with interrupts most likely needs some special
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treatment.
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Caveats
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-------
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The SDK files are imported to RTEMS from the NXP mcux-sdk git repository that
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you can find here: https://github.com/nxp-mcuxpresso/mcux-sdk/
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The directory structure has been preserved and all files are in a
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`bsps/arm/imxrt/mcux-sdk` directory. All patches to the files are marked with
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`#ifdef __rtems__` markers.
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The suggested method to import new or updated files is to apply all RTEMS
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patches to the mcux-sdk repository, rebase them to the latest mcux-sdk release
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and re-import the files. The new base revision should be mentioned in the commit
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description to make future updates simpler.
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A import helper script (that might or might not work on newer releases of the
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mcux-sdk) can be found here:
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https://raw.githubusercontent.com/c-mauderer/nxp-mcux-sdk/d21c3e61eb8602b2cf8f45fed0afa50c6aee932f/export_to_RTEMS.py
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Clocks and SDRAM
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----------------
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The clock configuration support is quite rudimentary. The same is true for
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SDRAM. It mostly relies on the DCD and on a static clock configuration that is
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taken from the NXP SDK example projects.
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The MPU settings are currently quite permissive.
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If you need to adapt the DCD or clock config to support a different hardware,
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you should generate these files using the NXP MCUXpresso Configuration Tools.
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You can add the generated files to your application to overwrite the default
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RTEMS ones or you can add them to RTEMS in a new BSP variant.
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There is no power management support.
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As a special case, the imxrt1052 BSP will adapt it's PLL setting based on the
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chip variant. The commercial variant of the i.MXRT1052 will use a core clock of
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600MHz for the ARM core. The industrial variants only uses 528MHz. For other
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chip or BSP variants, you should adapt the files generated with the MCUXpresso
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Configuration Tools.
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Caveats
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-------
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* The MPU settings are currently quite permissive.
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* There is no power management support.
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* On the i.MXRT1166, sleeping of the Cortex M7 can't be disabled even for
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debugging purposes. That makes it hard for a debugger to access the
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controller. To make debugging a bit easier, it's possible to overwrite the
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idle thread with the following one in the application:
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.. code-block:: c
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void * _CPU_Thread_Idle_body(uintptr_t ignored)
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{
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(void)ignored;
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while (true) {
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/* void */
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}
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}
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