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doc/sipeed/maix: describe RESET and BOOT button

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In the boot flow description add the RESET and BOOT button as well as the
function of the DTR and RTS lines of the serial interface.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
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Heinrich Schuchardt 2020-09-05 12:46:46 +02:00 committed by Andes
parent d53a95ba5e
commit 08bff30d5d
1 changed files with 6 additions and 2 deletions
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8
doc/board/sipeed/maix.rst
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@ -285,11 +285,15 @@ Technical Details
Boot Sequence
^^^^^^^^^^^^^
1. ``RESET`` pin is deasserted.
1. ``RESET`` pin is deasserted. The pin is connected to the ``RESET`` button. It
can also be set to low via either the ``DTR`` or the ``RTS`` line of the
serial interface (depending on the board).
2. Both harts begin executing at ``0x00001000``.
3. Both harts jump to firmware at ``0x88000000``.
4. One hart is chosen as a boot hart.
5. Firmware reads value of pin ``IO_16`` (ISP).
5. Firmware reads the value of pin ``IO_16`` (ISP). This pin is connected to the
``BOOT`` button. The pin can equally be set to low via either the ``DTR`` or
``RTS`` line of the serial interface (depending on the board).
* If the pin is low, enter ISP mode. This mode allows loading data to ram,
writing it to flash, and booting from specific addresses.