Hands-On Embedded Programming with C++17

Makefile-user.mk

In the root of the project folder, we find this Makefile. It contains a number of settings that we may want to set to suit our purposes:

Name	Description
COM_PORT	If we always connect the board to the same serial port, we can hardcode it here to save ourselves some typing.
SPI_MODE	This sets the SPI mode used while flashing the firmware images to the SPI ROM. With dio only two data lines (SD_D0, D1) or four (SD_D0-3). Not all SPI ROMs have all four data lines connected. The qio mode is faster, but dio should always work.
RBOOT_ENABLED	When set to 1, this enables rBoot bootloader support. We want this enabled.
RBOOT_BIG_FLASH	With 4 MB of ROM available, we wish to use all of this. Enable this ...