doc/sipeed/maix: describe RESET and BOOT button

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>
This commit is contained in:
Heinrich Schuchardt 2020-09-05 12:46:46 +02:00 committed by Andes
parent d53a95ba5e
commit 08bff30d5d

View file

@ -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.