.. highlight:: sh

.. _maple-ret6:

Maple RET6 Edition
==================

.. contents:: Contents
   :local:

Technical Specifications
------------------------

    * MCU: **STM32F103RET6**, a 32-bit ARM Cortex M3 microprocessor
    * Clock Speed: **72 MHz**
    * **512KB Flash** and **64KB SRAM**
    * 44 Digital I/O Pins (:ref:`GPIO <gpio>`)
    * 16 Analog Input pins, 12 bit **ADC** resolution (:ref:`ADC
      <adc>`)
    * Built-in, 2 channel **DAC** at 12 bit resolution
      (:ref:`libmaple-dac`).
    * 19 **PWM** pins at 16-bit resolution (:ref:`PWM <pwm>`)
    * Dedicated **USB** port for programming and communications
      (:ref:`USB<usb>`)
    * External **JTAG** interface (:ref:`JTAG <jtag>`)
    * 64 Channel nested vector interrupt handler (including
      :ref:`external interrupt <lang-attachinterrupt>` on GPIOs)
    * Integrated **SPI** (:ref:`SPI <spi>`)
    * Integrated **SDIO**
    * Integrated **I2C** and **I2S** (:ref:`I2C <i2c>`)
    * 12 Channels of Direct Memory Access (**DMA**)
      (:ref:`libmaple-dma`)
    * 3 **USART** and 2 **UART** devices (:ref:`USART <usart>`)
    * Two advanced control, four general purpose, two basic **timers**
      (:ref:`timers`)
    * Supplies up to 500mA @ 3.3v (with separate 250 mA digital and
      analog regulators)
    * Support for low power, sleep, and standby modes (<500uA)
    * Operating Voltage: 3.3V
    * Input Voltage (recommended): 3V-12V
    * Dimensions are 2.05″x2.1″

.. _maple-ret6-powering:

Powering the Maple RET6 Edition
-------------------------------

The Maple RET6 Edition's power source is determined by the header to
the left of the "LeafLabs" label on the silkscreen.  The RET6 Edition
can be powered from the barrel jack connector, USB, or a LiPo battery.
We ship the RET6 Edition with a jumper on the USB selector.  In order
to power it off of an alternative source, unplug the board, then move
the jumper to the desired selector before reconnecting power.

You can also power the Maple via the pin labeled "Vin" on the lower
header.  However, don't do this while simultaneously powering the
board from another source, or you could damage the it.

Using the Built-in Battery Charger
----------------------------------

The RET6 Edition has a built-in LiPo battery charger.  In order to use
it, put a jumper across the CHRG header on the power selection header
and across the USB, or EXT selectors, depending on whether you're
charging the battery via USB cable or barrel jack connector.  The LED
labeled CHRG will light up while the battery is being charged.  When
the battery is finished charging, the LED labeled DONE will also light
up.

.. _maple-ret6-gpios:

GPIO Information
----------------

The RET6 Edition features 38 ready-to-use general purpose input/output
(GPIO) pins for digital input/output, numbered ``D0`` through ``D37``.
These numbers correspond to the numeric values next to each header on
the Maple silkscreen.  More GPIOs (numbered ``D39``\ --``43``) are
available through use in combination with the
:ref:`lang-disabledebugports` function; see the :ref:`board-specific
debug pin constants <lang-board-values-debug>` for more information.

.. TODO [0.1.0] silkscreen pictures which expand abbreviations

.. _maple-ret6-pin-map-master:

Master Pin Map
^^^^^^^^^^^^^^

.. TODO [0.0.10] Update from base Maple information

This table shows the available functionality on every GPIO pin, by
peripheral type. The "STM32" column refers to the port and number that
the header is connected to on the microcontroller.  The "5V?" column
documents whether or not the pin is 5 volt tolerant.

.. csv-table::
   :header: "Pin", "STM32", ":ref:`ADC <adc>`", ":ref:`Timer <timers>`", ":ref:`I2C <i2c>`", ":ref:`UART <usart>`", ":ref:`SPI <spi>`", "5v?"

   "D0",  "PA3",  "ADC3",  "TIM2_CH4",     "-",          "USART2_RX",  "-",         "No"
   "D1",  "PA2",  "ADC2",  "TIM2_CH3",     "-",          "USART2_TX",  "-",         "No"
   "D2",  "PA0",  "ADC0",  "TIM2_CH1_ETR", "-",          "USART2_CTS", "-",         "No"
   "D3",  "PA1",  "ADC1",  "TIM2_CH2",     "-",          "USART2_RTS", "-",         "No"
   "D4",  "PB5",  "-",     "-",            "ISC1_SMBA",  "-",          "-",         "No"
   "D5",  "PB6",  "-",     "TIM4_CH1",     "I2C1_SCL",   "-",          "-",         "Yes"
   "D6",  "PA8",  "-",     "TIM1_CH1",     "-",          "USART1_CK",  "-",         "Yes"
   "D7",  "PA9",  "-",     "TIM1_CH2",     "-",          "USART1_TX",  "-",         "Yes"
   "D8",  "PA10", "-",     "TIM1_CH3",     "-",          "USART1_RX",  "-",         "Yes"
   "D9",  "PB7",  "-",     "TIM4_CH2",     "I2C1_SDA",   "-",          "-",         "Yes"
   "D10", "PA4",  "ADC4",  "-",            "-",          "USART2_CK",  "SPI1_NSS",  "No"
   "D11", "PA7",  "ADC7",  "TIM3_CH2",     "-",          "-",          "SPI1_MOSI", "No"
   "D12", "PA6",  "ADC6",  "TIM3_CH1",     "-",          "-",          "SPI1_MISO", "No"
   "D13", "PA5",  "ADC5",  "-",            "-",          "-",          "SPI1_SCK",  "No"
   "D14", "PB8",  "-",     "TIM4_CH3",     "-",          "-",          "-",         "Yes"
   "D15", "PC0",  "ADC10", "-",            "-",          "-",          "-",         "No"
   "D16", "PC1",  "ADC11", "-",            "-",          "-",          "-",         "No"
   "D17", "PC2",  "ADC12", "-",            "-",          "-",          "-",         "No"
   "D18", "PC3",  "ADC13", "-",            "-",          "-",          "-",         "No"
   "D19", "PC4",  "ADC14", "-",            "-",          "-",          "-",         "No"
   "D20", "PC5",  "ADC15", "-",            "-",          "-",          "-",         "No"
   "D21", "PC13", "-",     "-",            "-",          "-",          "-",         "No"
   "D22", "PC14", "-",     "-",            "-",          "-",          "-",         "No"
   "D23", "PC15", "-",     "-",            "-",          "-",          "-",         "No"
   "D24", "PB9",  "-",     "TIM4_CH4",     "-",          "-",          "-",         "Yes"
   "D25", "PD2",  "-",     "TIM3_ETR",     "-",          "-",          "-",         "Yes"
   "D26", "PC10", "-",     "-",            "-",          "-",          "-",         "Yes"
   "D27", "PB0",  "ADC8",  "TIM3_CH3",     "-",          "-",          "-",         "No"
   "D28", "PB1",  "ADC9",  "TIM3_CH4",     "-",          "-",          "-",         "No"
   "D29", "PB10", "-",     "-",            "I2C2_SCL",   "USART3_TX",  "-",         "Yes"
   "D30", "PB11", "-",     "-",            "I2C2_SDA",   "USART3_RX",  "-",         "Yes"
   "D31", "PB12", "-",     "TIM1_BKIN",    "I2C2_SMBA",  "USART3_CK",  "SPI2_NSS",  "Yes"
   "D32", "PB13", "-",     "TIM1_CH1N",    "-",          "USART3_CTS", "SPI2_SCK",  "Yes"
   "D33", "PB14", "-",     "TIM1_CH2N",    "-",          "USART3_RTS", "SPI2_MISO", "Yes"
   "D34", "PB15", "-",     "TIM1_CH3N",    "-",          "-",          "SPI2_MOSI", "Yes"
   "D35", "PC6",  "-",     "-",            "-",          "-",          "-",         "Yes"
   "D36", "PC7",  "-",     "-",            "-",          "-",          "-",         "Yes"
   "D37", "PC8",  "-",     "-",            "-",          "-",          "-",         "Yes"

.. TODO [0.0.10] Another table for the JTAG pins

Timer Pin Map
^^^^^^^^^^^^^

.. TODO [0.0.10] Add Timer 5,6,7,8 information

The following table shows what pins are associated with a particular
timer's capture/compare channels.

.. csv-table::
   :header: Timer, Ch. 1, Ch. 2, Ch. 3, Ch. 4
   :delim: |

   1 | D6  | D7  | D8  | -
   2 | D2  | D3  | D1  | D0
   3 | D12 | D11 | D27 | D28
   4 | D5  | D9  | D14 | D24

.. _maple-ret6-exti-map:

EXTI Line Pin Map
^^^^^^^^^^^^^^^^^

The following table shows which pins connect to which :ref:`EXTI lines
<external-interrupts-exti-line>` on the Maple RET6 Edition.

.. list-table::
   :widths: 1 1
   :header-rows: 1

   * - EXTI Line
     - Pins
   * - EXTI0
     - 2, 15, 27
   * - EXTI1
     - 3, 16, 28
   * - EXTI2
     - 1, 17, 25
   * - EXTI3
     - 0, 18
   * - EXTI4
     - 10, 19
   * - EXTI5
     - 4, 13, 20
   * - EXTI6
     - 5, 12, 35
   * - EXTI7
     - 9, 11, 36
   * - EXTI8
     - 6, 14, 37
   * - EXTI9
     - 7, 25, 28
   * - EXTI10
     - 8, 26, 29
   * - EXTI11
     - 30
   * - EXTI12
     - 31
   * - EXTI13
     - 21, 32
   * - EXTI14
     - 22, 33
   * - EXTI15
     - 23, 34

.. _maple-ret6-usart-map:

USART Pin Map
^^^^^^^^^^^^^

.. FIXME [0.0.10] UART4 and UART5 information

The Maple RET6 Edition has three serial ports (also known as a UARTs
or USARTs): ``Serial1``, ``Serial2``, and ``Serial3``. They
communicate using the pins summarized in the following table:

.. csv-table::
   :header: Serial Port, TX, RX, CK, CTS, RTS
   :delim: |

   ``Serial1`` | 7  | 8  | 6  | -  | -
   ``Serial2`` | 1  | 0  | 10 | 2  | 3
   ``Serial3`` | 29 | 30 | 31 | 32 | 33

Board-Specific Values
---------------------

.. TODO [0.0.10]

Stub.

Hardware Design Files
---------------------

The hardware schematics and board layout files are available in the
`Maple Github repository <https://github.com/leaflabs/maple>`_.  Other
than the processor used, the design files for the Maple RET6 edition
are identical to the Maple Rev 5, which are in the ``maple-r5``
subdirectory of the Maple repository.  A schematic for a JTAG adapter
suitable for use with Maple is available in the ``jtagadapter``
directory.

From the Github repository main page, you can download the entire
repository by clicking the "Download" button.  If you are familiar
with `git <http://git-scm.com/>`_, you can also clone the repository
at the command line with ::

    $ git clone git://github.com/leaflabs/maple.git

.. _maple-ret6-failure-modes:

Failure Modes
-------------

The following known failure modes apply to all Maple boards.  The
failure modes aren't design errors, but are easy ways to break or
damage your board permanently.

* **High voltage on non-tolerant pins**: not all header pins are 5V
  compatible; so e.g. connecting certain serial devices in the wrong
  way could over-voltage the pins.  The :ref:`pin-mapping master table
  <maple-ret6-pin-map-master>` details which pins are 5V-tolerant.

Errata
------

This section lists known issues and warnings for the Maple RET6 Edition.

* **Power Supply Marketing Mistake**: We originally sold the Maple
  advertising that it was capable of supplying up to 800 mA; the
  correct value is 500 mA.

* **UART4, UART5 GPIOs unavailable**: Pins related to the digital
  to analog converter (DAC) and UARTs 4 and 5 are not broken out to
  headers.  The RET6 Edition's hardware layout is identical to that of
  the Maple Rev 5, which wasn't designed for use with these
  STM32F103RET6-only peripherals.

* **DAC channel 2 on BOARD_LED_PIN**: The Maple Rev 5 connects PA5 to
  the board's built-in LED; this is the same GPIO bit which is
  connected to the DAC's channel 2 output.

* **Reset and NJTRST tied together**: The MCU's reset pin is tied to
  PB4, the NJTRST (JTAG reset) pin, which is pin 43.  Thus, attempting
  to use pin 43 as a GPIO will reset your board (and also prevents the
  JTAG "reset halt" command from working properly).

Recommended Reading
-------------------

* STMicro documentation for STM32F103RE microcontroller:

    * `Datasheet
      <http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/DATASHEET/CD00191185.pdf>`_ (PDF)
    * `Reference Manual
      <http://www.st.com/stonline/products/literature/rm/13902.pdf>`_ (PDF)
    * `Programming Manual
      <http://www.st.com/stonline/products/literature/pm/15491.pdf>`_
      (PDF; assembly language and register reference)