#
# hello.steptime1.RP2040.py
#
# 1 pin step-response loading measurement with PIO
#
# Neil Gershenfeld 7/24/24
# Modified by Michel Osee 3/20/26
#
# This work may be reproduced, modified, distributed,
# performed, and displayed for any purpose, but must
# acknowledge this project. Copyright is retained and
# must be preserved. The work is provided as is; no
# warranty is provided, and users accept all liability.
#
# install MicroPython
#    https://micropython.org/download/RPI_PICO/
#

from machine import Pin,freq
import rp2

@rp2.asm_pio(set_init=rp2.PIO.OUT_HIGH)
def steptimer():
    #
    # initialize
    #
    pull()
    mov(y,osr) # move loop to y
    pull() # move settle to osr
    mov(x,null) # move count to x
    set(pins,1) # turn on pin
    #
    # main loop
    #
    label('main loop')
    #
    # charge up
    #
    set(pindirs,1) # set pin to output
    #
    # settle up
    #
    label('up settle')
    mov(isr,x)
    mov(x,osr)
    label('up settle loop')
    jmp(x_dec,'up settle loop')
    mov(x,isr)
    #
    # discharge
    #
    set(pindirs,0) # set pin to input
    #
    # time down
    #
    label('down loop')
    jmp(pin,'down jump')
    jmp('down continue')
    label('down jump')
    jmp(x_dec,'down loop')
    #
    # loop
    #
    label('down continue')
    jmp(y_dec,'main loop')
    #
    # push count
    #
    mov(isr,x)
    push()
    
class steptime:
    def __init__(self,sm_id,pin):
        self._sm = rp2.StateMachine(sm_id,steptimer,
            jmp_pin=pin,set_base=pin)
        self._sm.active(True)
        self.get = self._sm.get
        self.put = self._sm.put

freq(250000000)

# MO modifications: pin ID changes and one input less
step0 = steptime(0,26)
step1 = steptime(1,27)
step2 = steptime(2,28)
step3 = steptime(3,29) # these are flipped in pinout

loop = 200
settle = 20000

min0 = min1 = min2 = min3 = 1e6

while True:
    step0.put(loop)
    step0.put(settle)
    result0 = 4294967296-step0.get() # +1 for init 0
    if (result0 < min0): min0 = result0
    step1.put(loop)
    step1.put(settle)
    result1 = 4294967296-step1.get()
    if (result1 < min1): min1 = result1
    step2.put(loop)
    step2.put(settle)
    result2 = 4294967296-step2.get()
    if (result2 < min2): min2 = result2
    step3.put(loop)
    step3.put(settle)
    result3 = 4294967296-step3.get()
    if (result3 < min3): min3 = result3
    print(f"7500,{result0-min0},{result1-min1},{result2-min2},\
       {result3-min3}") # 7500 for scale