#===================================================================
#  using C compilers for RaspberryPi Pico microcontroller images 
#===================================================================

After getting and unpacking the pico SDK and the cross-compiler for ARM, 
as detailed further below, the following can be done to compile a program
for the Pico board. 

# environment 

BASE=/opt/rpi_pico_sdk
export PICO_TOOLCHAIN_PATH=$BASE/arm-gnu-toolchain/arm-gnu-toolchain-12.2.mpacbti-rel1-x86_64-arm-none-eabi
export PICO_SDK_PATH=$BASE/pico-sdk  

# new build-dir 

BUILDPLACE=$HOME/build_pico
mkdir -pv  $BUILDPLACE
cd  $BUILDPLACE

cp -v  $BASE/pico-examples/{CMakeLists.txt,pico_sdk_import.cmake,pico_extras_import_optional.cmake,example_auto_set_url.cmake}  . 
cp -av $BASE/pico-examples/blink . 

vi  CMakeLists.txt     # remove other projects than 'blink' .. e.g. hello world, and all in the list at the end 

mkdir build 
cd build
cmake ..
cd blink/
make -j4   # or into subdir and make for that one specifically 


#---------------------------------------------------------------

# to load to the microprocessor board
# connect rpi pico board to computer by usb while holding its BOOTSEL button down, then release 
# this should cause it to start by presenting a ~130 MB usb storage device e.g. "/dev/sdb1" 

mount -t vfat -o rw /dev/sdb1 /mnt
cp $BUILDPLACE/build/blink/blink.uf2  /mnt/

# now it will stop being like a usb storage device, and the unmount will (probably) happen automatically


#---------------------------------------------------------------




#===================================================================
#  about the initial file-getting and setup 
#===================================================================

BASE=/opt/rpi_pico_sdk
mkdir $BASE
cd $BASE

#---------------------------------------------------------------

## get the gnu ARM toolchain, version for running on our architecture (x86_64) 
mkdir  arm-gnu-toolchain
cd  arm-gnu-toolchain
wget 'https://developer.arm.com/-/media/Files/downloads/gnu/12.2.mpacbti-rel1/binrel/arm-gnu-toolchain-12.2.mpacbti-rel1-x86_64-arm-none-eabi.tar.xz?rev=71e595a1f2b6457bab9242bc4a40db90&hash=41B9EE53CF6E77F7F0647767EC481951'  -O arm-gnu-toolchain-12.2.mpacbti-rel1-x86_64-arm-none-eabi.tar.xz 
xzcat <arm-gnu-toolchain-12.2.mpacbti-rel1-x86_64-arm-none-eabi.tar.xz | tar -xvpf -
cd ../
export PICO_TOOLCHAIN_PATH=$BASE/arm-gnu-toolchain/arm-gnu-toolchain-12.2.mpacbti-rel1-x86_64-arm-none-eabi


#---------------------------------------------------------------
## get the pico sdk and examples etc
git clone https://github.com/raspberrypi/pico-sdk.git --branch master
cd pico-sdk
git submodule update --init
cd ..
git clone https://github.com/raspberrypi/pico-examples.git --branch master     # handy for example CMake files
git clone https://github.com/raspberrypi/pico-extras.git --branch master       # not needed
git clone https://github.com/raspberrypi/pico-playground.git --branch master   # not needed 
export PICO_SDK_PATH=$BASE/pico-sdk  


#---------------------------------------------------------------
## make and (by cmake) set up build tree 
mkdir -pv nt/build
cd nt 
cp  ../pico-examples/CMakeLists.txt ../pico-examples/pico_extras_import_optional.cmake  ../../pico-examples/example_auto_set_url.cmake  ./ 
vi  CMakeLists.txt    # 

## do a build
cd build
cmake ..
cd blink/
make


#===================================================================