Move micropython UF2 to Pico following directions on Getting Started

download Thonny

in Thonny:
Tools > Options > Interpreter Tab
Choose generic micropython
Choose USB serial device (with appropriate device name)
==================================
In edit pane: Paste in:
from machine import Pin, Timer
led=Pin(25,Pin.OUT)
tim=Timer()
def tick(timer):
   led.toggle()
tim.init(freq=2.5,mode=Timer.PERIODIC,callback=tick)

Run current script
LED should blink
runs at 10KHz, fails at 100KHz and HANGS the system
have to unplug/plug to restart
==================================
from machine import Pin, Timer
led=Pin(15,Pin.OUT)
x=0
while (x<300000):
   led.toggle()
   x += 1

produces 24.6 KHz square wave with around 5% jitter
=> loop at ~50 KHz
==================================
import time
from rp2 import PIO, asm_pio
from machine import Pin

# Define the blink program.  It has one GPIO to bind to on the set instruction, which is an output pin.
# Use lots of delays to make the blinking visible by eye.
@asm_pio(set_init=rp2.PIO.OUT_LOW)
def blink():
    wrap_target()
    set(pins, 1)   [1]   
    set(pins, 0)   [1]   
    wrap()

# Instantiate a state machine with the blink program, at 1000Hz, with set bound to Pin(15) 
sm = rp2.StateMachine(0, blink, freq=100000000, set_base=Pin(15))

# Run the state machine for 3 seconds.  The LED should blink.
sm.active(1)
time.sleep(3)
sm.active(0)

Clock rate 100MHz, toggles i/o pin at 25 Mhz
Deleting the [1] delays bumps the toggle rate to 50 MHz!

============================================
Thonny can save a script directly to the MCU flash drive
and can erase a file.
If you save test.py, then at the command line type:
import test
starts it running
Typing:  tim.deinit() stops the timer-triggered routine
cntl-d also stops it
==================================
Choosing Tools>Open system shell
opens a console directly to the >>> prompt
(which is also at the bottom of the Thonny window)
Typing a CNTL-d does a soft reset

Typng help('modules') gives a list of modules
>>> help('modules')
__main__          framebuf          uasyncio/__init__ uio
_boot             gc                uasyncio/core     uos
_onewire          machine           uasyncio/event    urandom
_rp2              math              uasyncio/funcs    uselect
_thread           micropython       uasyncio/lock     ustruct
_uasyncio         onewire           uasyncio/stream   usys
builtins          rp2               ubinascii         utime
ds18x20           uarray            ucollections

Typing help(module) gives contents of the module
BUT you need to import it first!
=======================================
>>> help(machine)
object <module 'umachine'> is of type module
  __name__ -- umachine
  reset -- <function>
  reset_cause -- <function>
  bootloader -- <function>
  freq -- <function>
  mem8 -- <8-bit memory>
  mem16 -- <16-bit memory>
  mem32 -- <32-bit memory>
  ADC -- <class 'ADC'>
  I2C -- <class 'I2C'>
  SoftI2C -- <class 'SoftI2C'>
  Pin -- <class 'Pin'>
  PWM -- <class 'PWM'>
  SPI -- <class 'SPI'>
  SoftSPI -- <class 'SoftSPI'>
  Timer -- <class 'Timer'>
  UART -- <class 'UART'>
  WDT -- <class 'WDT'>
  PWRON_RESET -- 1
  WDT_RESET -- 3
what is mem8, mem16, mem32?
Mostly useful for read/write control registers
read: machine.mem32[address]
write: machine.mem32[address] = number
=== Generate address of an array ================
Assembler reference 
https://docs.micropython.org/en/latest/reference/asm_thumb2_index.html

a=array.array('b',[ 1, 2, 3])
@micropython.asm_thumb
# passing an array name to the assembler
# actually passes in the address
def addressof(r0):
    # r0 is the output register
    mov(r0, r0)

addr_a = addressof(a)
print(addr_a)
print(machine.mem8[addressof(a)])
==================
a=array.array('i',[ 1, 2, 3])
@micropython.asm_thumb
def addressof(r0):
    mov(r0, r0)
addr_a = addressof(a)
print(addr_a)
print(machine.mem32[addressof(a)+4]) #prints '2'
=================================================
>>> help (builtins)
object <module 'builtins'> is of type module
  __name__ -- builtins
  __build_class__ -- <function>
  __import__ -- <function>
  __repl_print__ -- <function>
  bool -- <class 'bool'>
  bytes -- <class 'bytes'>
  bytearray -- <class 'bytearray'>
  complex -- <class 'complex'>
  dict -- <class 'dict'>
  enumerate -- <class 'enumerate'>
  filter -- <class 'filter'>
  float -- <class 'float'>
  int -- <class 'int'>
  list -- <class 'list'>
  map -- <class 'map'>
  memoryview -- <class 'memoryview'>
  object -- <class 'object'>
  property -- <class 'property'>
  range -- <class 'range'>
  reversed -- <class 'reversed'>
  set -- <class 'set'>
  slice -- <class 'slice'>
  str -- <class 'str'>
  super -- <class 'super'>
  tuple -- <class 'tuple'>
  type -- <class 'type'>
  zip -- <class 'zip'>
  classmethod -- <class 'classmethod'>
  staticmethod -- <class 'staticmethod'>
  Ellipsis -- Ellipsis
  abs -- <function>
  all -- <function>
  any -- <function>
  bin -- <function>
  callable -- <function>
  chr -- <function>
  delattr -- <function>
  dir -- <function>
  divmod -- <function>
  eval -- <function>
  exec -- <function>
  getattr -- <function>
  setattr -- <function>
  globals -- <function>
  hasattr -- <function>
  hash -- <function>
  help -- <function>
  hex -- <function>
  id -- <function>
  input -- <function>
  isinstance -- <function>
  issubclass -- <function>
  iter -- <function>
  len -- <function>
  locals -- <function>
  max -- <function>
  min -- <function>
  next -- <function>
  oct -- <function>
  ord -- <function>
  pow -- <function>
  print -- <function>
  repr -- <function>
  round -- <function>
  sorted -- <function>
  sum -- <function>
  BaseException -- <class 'BaseException'>
  ArithmeticError -- <class 'ArithmeticError'>
  AssertionError -- <class 'AssertionError'>
  AttributeError -- <class 'AttributeError'>
  EOFError -- <class 'EOFError'>
  Exception -- <class 'Exception'>
  GeneratorExit -- <class 'GeneratorExit'>
  ImportError -- <class 'ImportError'>
  IndentationError -- <class 'IndentationError'>
  IndexError -- <class 'IndexError'>
  KeyboardInterrupt -- <class 'KeyboardInterrupt'>
  KeyError -- <class 'KeyError'>
  LookupError -- <class 'LookupError'>
  MemoryError -- <class 'MemoryError'>
  NameError -- <class 'NameError'>
  NotImplementedError -- <class 'NotImplementedError'>
  OSError -- <class 'OSError'>
  OverflowError -- <class 'OverflowError'>
  RuntimeError -- <class 'RuntimeError'>
  StopAsyncIteration -- <class 'StopAsyncIteration'>
  StopIteration -- <class 'StopIteration'>
  SyntaxError -- <class 'SyntaxError'>
  SystemExit -- <class 'SystemExit'>
  TypeError -- <class 'TypeError'>
  ValueError -- <class 'ValueError'>
  ViperTypeError -- <class 'ViperTypeError'>
  ZeroDivisionError -- <class 'ZeroDivisionError'>
  open -- <function>

=================================================
Does @micropython.asm_thumb work?