First version of a DeepSleep state for the RP2040 (#4976)

* Adding pico-extra utils

* RP2040 can now go to deepsleep

* First RP2040 DeepSleep code - TODO : do better and restore

* FIX RAK11310 compilation (revert SDK + missing defines)

---------

Co-authored-by: Ben Meadors <benmmeadors@gmail.com>

variants/rak11310/platformio.ini

@@ -2,6 +2,8 @@
 extends = rp2040_base
 board = wiscore_rak11300
 upload_protocol = picotool
+# keep an old SDK to use less memory.
+platform_packages = framework-arduinopico@https://github.com/earlephilhower/arduino-pico.git#3.7.2
 
 # add our variants files to the include and src paths
 build_flags = ${rp2040_base.build_flags} 

variants/rak11310/variant.h

@@ -6,6 +6,7 @@
 
 #define LED_CONN PIN_LED2
 #define LED_PIN LED_BUILTIN
+#define ledOff(pin) pinMode(pin, INPUT)
 
 #define BUTTON_PIN 9
 #define BUTTON_NEED_PULLUP

variants/rp2040-lora/variant.h

@@ -23,6 +23,7 @@
 //  ratio of voltage divider = 3.0 (R17=200k, R18=100k)
 // #define ADC_MULTIPLIER 3.1 // 3.0 + a bit for being optimistic
 
+#define HAS_CPU_SHUTDOWN 1
 #define USE_SX1262
 
 #undef LORA_SCK