.. _mimx8mp_phyboard_pollux:

PhyBOARD Pollux (NXP i.MX8M Plus)
#################################

Overview
********

The PhyBOARD Pollux is based upon the PhyCore-i.MX8M Plus SOM which is based on
the NXP i.MX8M Plus SoC. The SoC includes four Coretex-A53 cores and one
Coretex-M7 core for real time applications like Zephyr. The PhyBOARD Pollux
can be used for various applications like SmartHomes, Industry 4.0, IoT etc.
It features a lots of interfaces and computing capacity. It can be used as
a reference, to develop or in the final product too.


Board features:

- Memory:

   - RAM: 256MB - 8GB LPDDR4
   - EEPROM: 4kB - 32kB
   - eMMC: 4GB - 64GB (eMMC 5.1)
   - SPI NOR Flash: 4MB - 256MB
- Interfaces:

   - Ethernet: 2x 10/100/1000BASE-T (1x TSN Support)
   - USB: 2x 3.0 Host
   - Serial: 1x RS232 / RS485 Full Duplex / Half Duplex
   - CAN: 2x CAN FD
   - Digital I/O: via Expansion Connector
   - PCIe: 1x miniPCIe
   - MMX/SD/SDIO: microSD slot
   - Display: LVDS(1x4 or 1x8), MIPI DSI(1x4), HDMI
   - Audio: SAI
   - Camera: 2x MIPI CSI-2 (PhyCAM-M)
   - Expansion Bus: I2C, SPI, SDIO, UART, USB
   - JTAG: via PEB-EVAL-01
- LEDs:

   - 1x Multicolor Status LED via I2C


.. image:: img/Phyboard_Pollux.jpg
   :width: 720px
   :align: center
   :height: 405px
   :alt: PhyBOARD Pollux

More information about the board can be found at the
`PHYTEC website`_.

Supported Features
==================

The Zephyr mimx8mp_phyboard_polis board configuration supports the following hardware
features:

+-----------+------------+-------------------------------------+
| Interface | Controller | Driver/Component                    |
+===========+============+=====================================+
| NVIC      | on-chip    | nested vector interrupt controller  |
+-----------+------------+-------------------------------------+
| SYSTICK   | on-chip    | systick                             |
+-----------+------------+-------------------------------------+
| CLOCK     | on-chip    | clock_control                       |
+-----------+------------+-------------------------------------+
| PINMUX    | on-chip    | pinmux                              |
+-----------+------------+-------------------------------------+
| UART      | on-chip    | serial port-polling;                |
|           |            | serial port-interrupt               |
+-----------+------------+-------------------------------------+
| GPIO      | on-chip    | GPIO output                         |
|           |            | GPIO input                          |
+-----------+------------+-------------------------------------+

The default configuration can be found in the defconfig file:
:zephyr_file:`boards/arm/mimx8mp_phyboard_polis/mimx8mm_phyboard_polis_defconfig`.

It's recommended to disable peripherals used by the M7-Core on the host running
on the Linux host.

Other hardware features are not currently supported with Zephyr on the
M7-Core.

Connections and IOs
===================

The following Compontens are tested and working correctly.

UART
----

+---------------+-----------------+-----------------------------------+
| Board Name    | SoM Name        | Usage                             |
+===============+=================+===================================+
| Debug USB(A53)| UART1           | UART Debug Console via USB        |
+---------------+-----------------+-----------------------------------+
| Wo WiFi Module| UART3           | UART to WiFi/BLE Module           |
+---------------+-----------------+-----------------------------------+
| Debug USB(M4) | UART4           | UART Debug Console via USB        |
+---------------+-----------------+-----------------------------------+

.. note::
  Please note, that the, to UART3 connected, Wifi/BLE Module isn't working with
  Zephyr yet. UART3 can also be used through pin 31(RX) and 33(TX) of the
  X6 Connector.

GPIO
----

The pinmuxing for the GPIOs is the standard pinmuxing of the mimx8mp devicetree
created by NXP. You can find it here:

:zephyr_file:`dts/arm/nxp/nxp_imx8ml_m7.dtsi`.

The Pinout of the PhyBOARD Polis can be found here:

`PHYTEC website`_

Programming and Debugging
*************************

The i.MX8MP does not have a separate flash for the M7-Core. Because of this
the A53-Core has to load the program for the M7-Core to the right memory
address, set the PC and start the processor.
This can only by done with u-boot at the moment. We are working on our BSP to
enable remoteproc support.

The M7 can use up to 3 different RAMs (currently, only two configurations are
supported: ITCM and DDR). These are the memory mapping for A53 and M7:

+------------+-------------------------+------------------------+-----------------------+----------------------+
| Region     | Cortex-A53              | Cortex-M7 (System Bus) | Cortex-M7 (Code Bus)  | Size                 |
+============+=========================+========================+=======================+======================+
| OCRAM      | 0x00900000-0x0098FFFF   | 0x20200000-0x2028FFFF  | 0x00900000-0x0098FFFF | 576KB                |
+------------+-------------------------+------------------------+-----------------------+----------------------+
| DTCM       | 0x00800000-0x0081FFFF   | 0x20000000-0x2001FFFF  |                       | 128KB                |
+------------+-------------------------+------------------------+-----------------------+----------------------+
| ITCM       | 0x007E0000-0x007FFFFF   |                        | 0x00000000-0x0001FFFF | 128KB                |
+------------+-------------------------+------------------------+-----------------------+----------------------+
| OCRAM_S    | 0x00180000-0x00188FFF   | 0x20180000-0x20188FFF  | 0x00180000-0x00188FFF | 36KB                 |
+------------+-------------------------+------------------------+-----------------------+----------------------+
| DDR        | 0x80000000-0x803FFFFF   | 0x80200000-0x803FFFFF  | 0x80000000-0x801FFFFF | 2MB                  |
+------------+-------------------------+------------------------+-----------------------+----------------------+

For more information about memory mapping see the
`i.MX 8M Plus Applications Processor Reference Manual`_  (section 2.1 to 2.3)

At compilation time you have to choose which memory region will be used. This
configuration is done in the devicetree and the defconfig / the config of your
program.

**By default Zephyr will use the TCM memory region.** You can configure it like
this for the DDR region:

In the devicetree overwrite the following nodes like this:

.. code-block:: DTS

   chosen {
      /* TCM */
      zephyr,flash = &itcm;
	   zephyr,sram = &dtcm;
   };

change it to

.. code-block:: DTS

   chosen {
      /* DDR */
      zephyr,flash = &ddr_code;
      zephyr,sram = &ddr_sys;
   };


In your prj.conf overwrite the configuration like this for the **DDR** memory
region:

.. code-block:: console

   CONFIG_CODE_DDR=y
   CONFIG_CODE_ITCM=n


Starting the M7-Core via U-Boot
===============================

Load the compiled zephyr.bin to memory address 0x4800000.
This should output something like this:

.. code-block:: console

   u-boot=> tftp 0x48000000 192.168.3.10:zyphr.bin
   Using ethernet@30be0000 device
   TFTP from server 192.168.3.10; our IP address is 192.168.3.11
   Filename 'zepyhr.bin'.
   Load address: 0x48000000
   Loading: ##
            2 KiB/s
   done
   Bytes transferred = 27240 (6a68 hex)

Because it's not possible to load directly to the TCM memory area you have to
copy the binaries. The last argument given is the size of the file in bytes,
you can copy it from the output of the last command.

.. code-block:: console

   u-boot=> cp.b 0x48000000 0x7e0000 27240

And finaly starting the M7-Core at the right memory address:

.. code-block:: console

   u-boot=> bootaux 0x7e0000
   ## Starting auxiliary core stack = 0x20003A58, pc = 0x1FFE1905...

Debugging
=========

The PhyBOARD Polis can be debugged using a JTAG Debugger.
The easiest way to do that is to use a SEGGER JLink Debugger and Phytec's
``PEB-EVAL-01`` Shield, which can be directly connected to the JLink.
You can find the JLink Software package here: `JLink Software`_

.. figure:: img/PEB-EVAL-01.jpg
   :alt: PEB-EVAL-01
   :width: 350

   PEB-EVAL-01

To debug efficiently you have to use multiple terminals:

After connecting everything and building with west use this command while in
the directory of the program you build earlier to start a debug server:

.. code-block:: console

   host$ west debugserver

West automatically connects via the JLink to the Target and keeps open a
debug server.

Use another terminal, start gdb, connect to target and load Zephyr on the
target:

.. code-block:: console

   host$ gdb-multiarch build/zephyr/zephyr.elf -tui
   (gdb) targ rem :2331
   Remote debugging using :2331
   0x1ffe0008 in _vector_table ()
   (gdb) mon halt
   (gdb) mon reset
   (gdb) c
   Continuing.

The program can be debugged using standard gdb techniques.

References
==========

.. _PHYTEC website:
   https://www.phytec.de/produkte/single-board-computer/phyboard-pollux/

.. _i.MX 8M Plus Applications Processor Reference Manual:
   https://www.nxp.com/webapp/Download?colCode=IMX8MPRM

.. _JLink Software:
   https://www.segger.com/downloads/jlink/