# py4sup_ch8_dcm_serial_v1a 
# dew.ninja Apr 2024
# supplement of dcm_1joint
# connect to serial port of computer to exchange date
# update list:
# Apr 2024:
#       - add $ to command and response so that it can be removed on the other side
#       - use virtual serial port COM7 <-> COM8

# originally dcm1_controllers.py
# dew.ninja  Sep 2023
# wokwi version using PWM/DIR control
# Controller implementation for dcm1 plant on Wokwi
# modified from sfic_ofc_pid_lag3.py

import time
from utime import sleep_ms 
from machine import Pin,Timer, PWM, ADC, DAC, I2C #,UART
from neopixel import NeoPixel
#import sys

# ---- code for SSD1306 OLED. Comment out if it is not available 
import ssd1306

# --- uart initialization -----
#uart = UART(1, 115200)


# ---- 4-point moving average
# ---- class implementation seems to have problem -------
# from ma4 import MA4
# mafilter = 1  # set to 1 to use average filter
# ma4=MA4()

# 4-point moving average implemented as function
# has 2 channels for y and x2

streaming = 0  # streaming mode flag
capture = 0  # capture mode 0 = off, 1 = on
stream_downsamp = 10 # downsampling data stream
datacnts = 0  

T = 0.01  # sampling period
T_ms = int(1000*T)
mafilter = 0
import array
ma_y = array.array('f',0.0 for _ in range (8))
ma_i = array.array('i',0 for _ in range (2))
ma_ysum = array.array('f',0.0 for _ in range (2))
ma_yavg = array.array('f',0.0 for _ in range (2))

def ma4_fn(ch, y): # ch = 0/1  for y/x2
    global ma_y, ma_i, ma_ysum, ma_yavg
    i = 4*ch+ma_i[ch] 
    ma_ysum[ch] -= ma_y[i]
    ma_y[i] = y
    ma_ysum[ch] += ma_y[i]
    ma_yavg[ch] = ma_ysum[ch]/4
    ma_i[ch]+=1
    if ma_i[ch]>3:
        ma_i[ch] = 0
    return ma_yavg[ch]



# ESP32 Pin assignment 
i2c = I2C(0, scl=Pin(22), sda=Pin(21))

oled_width = 128
oled_height = 64
oled = ssd1306.SSD1306_I2C(oled_width, oled_height, i2c)

def oled_showryu(oled,r,y,u,ulim,x2):
    oled.fill(0)
    rtxt = "r : "+str(round(r*100,2)) +" deg."
    ytxt = "y : "+str(round(y*100,2))+" deg."
    utxt = "u : "+str(round(u,2))
    ulimtxt = "ulim : "+str(round(ulim,2))
    x2txt = "x2 : "+str(round(x2,2))
    oled.text(rtxt,0,0)
    oled.text(ytxt,0,12)
    oled.text(utxt,0,24)
    oled.text(ulimtxt,0,36)
    oled.text(x2txt,0,48)
    oled.show()

oled_tprev = 0
#oled_showryu(oled,1,2,3)   
# --------------------------------
# ----------neopixels representing motor movement ------------
NeoPixel_Pin = 15
NUMPIXELS = 24
pixels = NeoPixel(Pin(NeoPixel_Pin),NUMPIXELS)
#pixels[23]=(255,0,0) # test
#pixels.write()
def pixels_display():
    angle_per_pixel = 360/NUMPIXELS  # actually 360/24 but can adjust a bit
    pixels.fill((0,0,0))
    rpixel = int(r*100/angle_per_pixel) # pixel of command r
    if rpixel<0:
        rpixel = 0
    if rpixel>NUMPIXELS-1:
        rpixel = NUMPIXELS-1
    ypixel = int(y*100/angle_per_pixel) # pixel of plant output y
    if ypixel<0:
        ypixel = 0
    if ypixel>NUMPIXELS-1:
        ypixel = NUMPIXELS-1
    if rpixel == ypixel: # r match y exactly
        pixels[rpixel] = (255,255,0) # red + green
    else:
        pixels[rpixel] = (0,255,0) # command in green
        pixels[ypixel] = (255,0,0) # plant output in red
    pixels.write()


# ------------------------------------------------
# -------------- adjust commad using VR ------------------
RCMD_PIN = 34
r_from_VR = False # change to true by r = -1
r_in = ADC(Pin(RCMD_PIN))
r_in.atten(ADC.ATTN_11DB) # range 0 - 3.6 V


# ---------------------------------------------
prompt = False  # set prompt off/on so that it won't get in the way.

# range variables
PWMMAX = 1023  # maximum PWM value
PWMMID = 511
PWMMIN = 0
DACMAX = 255
DACMID = 127
DACMIN = 0
ADCMAX = 4095
ADCMID = 2047
ADCMIN = 0
UMAX = 3.3  # limit max controller output to 3.2 vols
UMID = 1.65
UMIN = 0.1 # min controller output
VEL_OFFSET = 2.0  # adjust this

pwm_out = PWM(Pin(5))  # output to lag3 board. Change from 16 to 5 for Wokwi
pwm_out.freq(1000) # set PWM frequency to 1 KHz (lower from 5KHz)
dac_out = DAC(Pin(25)) # this doesn't work on Wokwi
dir_out = Pin(19,Pin.OUT) # direction 0 = CW, 1 = CCW

y_in = ADC(Pin(39)) # ADC1_CH3. Shown as VN on Wokwi
y_in.atten(ADC.ATTN_11DB) # range 0 - 3.6 V



adc2v = 3.6/ADCMAX  # max of ADC is set to 3.6 v by the package
v2deg = 100 # convert volt to degree
v2pwm = int(PWMMAX/3.3)
v2dac = int(DACMAX/3.3)
vel_offset = 1.8  # use the same value as in chip


led = Pin(2, Pin.OUT)


t_data = 0  # time data output

# now can choose between PID and output-feedback controller (OFC)
# controller = 0, 1, 2 (PID, OFC, SFC)
controller = 0
plantsim = 0 # plant simulation mode. Plantsim is not available in this program.

# global variable for LSID
lsid = False  # flag
PRBSVal = 1 # PRBS value, unit in volt
feedin = 0
bvec =[0]*13 # unit delay output
bvec[1] = bvec[2] = bvec[6] = bvec[7] = bvec[10] = bvec[12] = 1

# values for these PID coefficients are computed in PID_update
bi = 0
ad = 0
bd = 0
bt = 0

# controller states
ep = 0  # error for proportional term
e1 = 0  # true error (for integral term)
e0 = 0
eus1 = 0 # error for back calculation term 
eus0 = 0
ed1 = 0  # error for derivative term
ed0 = 0
ui1 = 0  # integral-term outputs
ui0 = 0
ud1 = 0  # derivative-term outputs
ud0 = 0

# PID parameters
kp = 300  # PID gains
ki = 1.0
kd = 500
kt = 0.1  # back calculaiton gain
wp = 1  # proportional weight
wd = 1  # derivative weight
N = 50  # derivative filter coefficient

# --- global variables for output-feedback controller ----
# integrator (this may be used later for integrator + sfb shcieme
def integrator_coeff_compute():
    return 0.5*T

a_int = integrator_coeff_compute()

# integrator states
u0_int = 0.0 # output
u1_int = 0.0 # past-output
e0_int = 0.0 # input
e1_int = 0.0 # past-input

def integrator(inp):  # integrator function. Used for SFBI or custom control
    global u0_int, u1_int, e0_int, e1_int
    e1_int = e0_int
    e0_int = inp
    u1_int = u0_int
    u0_int = u1_int + a_int*(e0_int + e1_int)
    return u0_int
    

def leadlag_coeff_compute(a,b): # a = zero, b = pole
    alpha1 = 2+a*T
    alpha2 = a*T - 2
    beta1 = 2+b*T
    beta2 = b*T-2
    gamma1 = -beta2/beta1
    gamma2 = alpha1/beta1
    gamma3 = alpha2/beta1
    return gamma1, gamma2, gamma3


K_ofc = 8000  # output-feedback controller gain 
ll_z = 5 # lead-lag zero
ll_p = 40 # lead-lag pole
g_1, g_2, g_3 = leadlag_coeff_compute(ll_z, ll_p)

# lead-lag states
u0_ll = 0.0 # output
u1_ll = 0.0 # past-output
e0_ll = 0.0 # input
e1_ll = 0.0 # past-input

def leadlag(inp):  # lead-lag compute
    global u0_ll, u1_ll, e0_ll, e1_ll
    e1_ll = e0_ll
    e0_ll = inp
    u1_ll = u0_ll
    u0_ll = g_1*u1_ll + g_2*e0_ll + g_3*e1_ll 
    return u0_ll

# ----- state feedback controller--------
# ---- state measurement -----
# pins used for state feedback is
# x2 = 32, x1(y) = 39

x_2 = ADC(Pin(32))
x_2.atten(ADC.ATTN_11DB)



# ---- variables for autotuning ----
autotune = False  # turn autotune off/on
#relay_a = 0.0 # amplitude of output oscillation
relay_d = 1.0  # relay output level
cycle_cnts = 0  # count oscillation cycles before measuring Tu
at_ready2measure = False  # flag to starts measuring osc magnitude and period
at_time = 0.0  # time since autotuning starts
Tu = 0.0 # ultimate period
Ku = 0.0 # ultimate gain
at_x_old = at_x_new = 0.0  # time output crosses zero (or UMID)
y_max = 0.0  # keep maximum y to compute at_a

r = 1.0  # ref. cmd
u = r   # plant input
ulim = r
u_pwm = u*v2pwm
y = 0.0  # plant output
y_old = 0.0  # previous plant output


datasize = 200  # number of points in output capture

capture_flag = False # indicates start/stop of data transfer
data_idx = 0  # data index
# ---- controller -----
feedback = 1  # 0 = open-loop, 1 = close-loop


timer=Timer(1)


# --- Functions for autotuning mode ----
# function to limit output between UMIN, UMAX and add offset UMID
def limit_and_offset(u):
    u_lim = u
    if u > UMID:
        u_lim = UMID         # limit u to UMID
    elif u < -UMID:
        u_lim = -UMID         # limit u to -UMID
    u_lim += UMID
    return u_lim

# ------ function to generate pwm/dir outputs from controller output u
def convert2pwmdir(u):
    u_lim = u
    if u > UMAX:
        u_lim = UMAX         # limit u to UMAX
    elif u < -UMAX:
        u_lim = -UMAX         # limit u to -UMAX
    if u_lim >= 0:   # positive u_lim = CW direction
        u_dir = 0
        u_pos = u_lim
    else:
        u_dir = 1
        u_pos = -u_lim
    return u_lim,u_pos, u_dir

 

 # ---------------------------------------------------
def relay(y,d):  # implement relay device
    if plantsim:
        if y>0:
            rout = -d
        else:
            rout = d
    else:
        if y>UMID:
            rout = -d
        else:
            rout = d        
    return rout

# measure oscillation amplitude period after 3 cycles
def measure_amp_period(): 
    global at_ready2measure,cycle_cnts,at_time,at_x_old,at_x_new,\
           Ku,Tu,y,y_max, autotune, prompt
    at_time+= T  # increase time during autotuning
    if cycle_cnts>2:
        #print('y = '+str(y))
        #print('y_max = '+str(y_max))
       
        if y > y_max: # keep maximum value
            y_max = y
    if plantsim:
        if y_old < 0.0 and y >= 0.0: # crossing zero detected
            at_x_old = at_x_new
            at_x_new = at_time
            cycle_cnts += 1  # cound osc cycle
            if not capture_flag:
                print("$Oscillation cycle : "+str(cycle_cnts))
    else:
        if y_old < UMID and y >= UMID: # crossing UMID detected
            at_x_old = at_x_new
            at_x_new = at_time
            cycle_cnts += 1  # cound osc cycle
            if not capture_flag:
                print("$Oscillation cycle : "+str(cycle_cnts))
    if cycle_cnts == 4:
        at_ready2measure = True
    if at_ready2measure:
        Tu = at_x_new - at_x_old
        if not capture_flag:
            print("$Tu = "+str(Tu))
        if plantsim:
            at_a = y_max
        else:
            at_a = y_max - UMID
        Ku = 7*(4*relay_d)/(22*at_a)
        if not capture_flag:
            # print("a = "+str(at_a))
            print("$Ku = "+ str(Ku))
            print("$Autotuning ends.")
        autotune = False
        at_pid_adjust()
        #prompt=True
        if not capture_flag:
            #sys.stdout.write('\nEnter command : ') # show prompt
            print("\n$Enter command : ")

def at_pid_adjust():
    global kp, ki, kd, Ku, Tu
    if not capture_flag:
        print("$Updating PID parameters with Ku and Tu ")
    kp = 0.6*Ku
    ki = 1.2*Ku/Tu
    kd = 0.075*Ku*Tu
    if not capture_flag:
        print("$kp = " + str(kp))
        print("$ki = " + str(ki))
        print("$kd = " + str(kd))
    PID_update()

# compute PID coefficients, also update freeboard
def PID_update():
    global ad, bd, bi, bt
    bi = 0.5*T*ki
    bt = 0.5*T*kt
    ad1 = 1+0.5*N*T
    ad2 = 0.5*N*T - 1
    ad = -ad2/ad1
    bd = kd*N/ad1
    #update_dashboard()  


# PID controller function
def PID_controller(r,y):
    global e1,e0,ed1,ed0, eus1,eus0, ui1, ui0, ud1, ud0, u
    
    # state transfer
    e1 = e0
    ed1 = ed0
    eus1 = eus0
    
    ui1 = ui0
    ud1 = ud0
    # compute errors for each term
    e0 = r - y
    ep0 = wp*r - y # weighted proportional error
    ed0 = wd*r - y # weighted derivative error
    
    up0 = kp*ep0 # output of P term
    ui0 = ui1 +bi*(e0+e1) + bt*(eus0+eus1) # output of I term
    ud0 = ad*ud1 +bd*(ed0 - ed1) # output of D term
    u = up0 + ui0 + ud0
    #u_lim = limit_and_offset(u)
    return u

# output-feedback controller function
def OFC_controller(r,y):
    u1 = leadlag(r-y)
    #u2 = integrator(u1)
    return K_ofc*u1

# state-feedback controller
K_sfic = [10,13.9]  # state feedback gain
#ff_gain = 324  # feedforward gain
Ki_sfic = 4

def SFIC_controller(r,x2,y):   
    u = Ki_sfic*integrator(r-y) -K_sfic[0]*y -K_sfic[1]*x2 
    return u
    


# PRBS generator function
def PRBS_generator():
    global bvec, feedin, PRBSVal
    feedin = bvec[0] ^ (bvec[2]^(bvec[3]^ bvec[12]))
    for j in range(12,1,-1):  
        bvec[j] = bvec[j-1]
        #print(bvec[j])
    bvec[1] = feedin
    u_out = PRBSVal*(2*bvec[12] - 1)
    return u_out

# ------------------- timer routine -------------------------------
# ----------------feedback is executed here ---------------
def timer_isr(event):
    global a,b,T,u,ulim, u_states, y_states, capture_flag,t_data, \
           data_idx,datasize, prompt, y, y_old, lsid, oled_tprev, \
            oled,r, datacnts
    led.value(not led.value())
    if r_from_VR:
        r=r_in.read()*adc2v
    #y_adc = y_in.read()  # read from ADC
    #y1 = y_adc*adc2v  # convert to volt
    y_old = y
    # if plantsim:
    #     y,x2,x1 = lag3(a,b,T,u, u_states, y_states) # simulation. in volt
    # else:
        # y = y_in.read_uv()*1e-6 # from electronics
        # x1 = x_1.read_uv()*1e-6
        # x2 = x_2.read_uv()*1e-6
    yr = y_in.read()*adc2v # works better on Wokwi
    x2r = x_2.read()*adc2v - vel_offset  # need to offset this properly
    #print(yr)
    if mafilter: # perform 4-point average
        # y = ma4.compute(yr)
        # x2 = ma4.compute(x2r)
        y = ma4_fn(0,yr)
        x2 = ma4_fn(1,x2r)
    else:
        y = yr
        x2 = x2r
    #y2rgb() # just lid RGB LED. Not discussed in book.
    if feedback:
        if controller==0: # PID selected
            if autotune:
                u = relay(y,relay_d)
                #ulim = limit_and_offset(u)
                ulim, upos, udir = convert2pwmdir(u)
                measure_amp_period()
            else:
                u = PID_controller(r,y)
                ulim, upos, udir = convert2pwmdir(u)

        elif controller==1: # output-feedback controller
            u = OFC_controller(r,y)
            ulim, upos, udir = convert2pwmdir(u)

            #ulim = limit_and_offset(u)
        elif controller==2: # state-feedback controller
            u = SFIC_controller(r,x2,y)
            ulim, upos, udir = convert2pwmdir(u)
    else:
        if lsid: # LSID mode
            u = PRBS_generator()
            ulim, upos, udir = convert2pwmdir(u)
        else:    # open-loop 
            u = r
            ulim, upos, udir = convert2pwmdir(u)
    # print("ulim={},upos={},udir={}".format(ulim,upos,udir))
    u_pwm = int(upos*v2pwm) # v2pwm = int(PWMMAX/3.3)
    #print(u_pwm)
    pwm_out.duty(u_pwm)  # send output via PWM pin 16
    dir_out.value(udir)  # direction 0 = CW, 1 = CCW
    # pwm_out.duty(PWMMAX)
    #u_dac = int(ulim*v2dac) # v2dac = int(DACMAX/3.3)
    #dac_out.write(u_dac) # also send output to DAC1
    # --- remove these lines if SSD1306 is not available ---
    oled_tcurrent = time.ticks_ms()
    if (oled_tcurrent - oled_tprev)>300: # display every 300 ms
        oled_tprev = oled_tcurrent
        oled_showryu(oled,r,y,u,ulim,x2)
        pixels_display()  # display angle on NeoPixels
    # ---------------------------------------------
    
    if streaming: # send confinuous data
        if datacnts == stream_downsamp:
            print("{},{},{},{},{},{}".format(round(t_data,2),100*r,100*y,ulim,u,100*x2))                    
            t_data+=(T*datacnts)
            datacnts = 0
        else:
            datacnts += 1
    elif capture_flag:
        print("[{},{},{},{},{},{}],".format(round(t_data,2),100*r,100*y,ulim,u,100*x2))                    
        t_data+=T
        data_idx+=1
        if data_idx==datasize:
            data_idx = 0
            t_data = 0.0
            capture_flag = False  # stop capture data 
            print("])")  # end of np.array([ command
            #prompt=True  # prompt on
            if lsid:
                print("$LSID ends.")
                lsid = False # LSID mode ends

# helper function for cmdInt()
# separate command and parameter
# at "="
def splitCmd(userstr):
    result = userstr.find("=")
    if result == -1:
        noparm = 1
        cmdstr = userstr.strip()
        parmstr = '' # not used
    else:
        noparm = 0
        splitstr = userstr.split("=")
        cmdstr = splitstr[0].strip()
        parmstr = splitstr[1].strip()
    return cmdstr, parmstr, noparm

#command interpreter function
def cmdInt(userstr):
    global r,datasize,capture,capture_flag,feedback,T,T_ms,a,b, prompt, mafilter,\
           kp,ki,kd,kt,wp,wd,N, autotune, y, y_max, at_ready2measure, at_time,\
           at_x_old, at_x_new, cycle_cnts, lsid,a_int,g_1,g_2,g_3, \
            controller,r_from_VR, streaming, t_data, datacnts
    cmdstr, parmstr, noparm = splitCmd(userstr)

    if cmdstr.lower() == "$r" or cmdstr.lower() == "$step":
        # toggle_mode = 0  # turn off toggle mode
        # for this DCM model, r is specified in degrees
        if noparm==1: # retrieve current r 
            print("$"+str(r))
        else:
            r_tmp = float(parmstr)
            if r_tmp==-1: # change to cmd from VR mode
                r_from_VR = True
                print("$Ref. comd is now from VR")
            else:
                r_from_VR = False
                if r_tmp > 330:  # limit range 
                    r_tmp = 330
                elif r_tmp < 0.0: 
                    r_tmp = 0.0
                r = r_tmp/100
        if capture:  # capture mode on
            capture_flag = True
            print("datamat = np.array([")  # head of data matrix
            prompt=False # turn prompt off 
        # update_dashboard()
    # elif cmdstr.lower() == "psim":
    #     if noparm==1:
    #         print(plantsim)
    #     else:            
    #         plantsim = int(parmstr)
    #         if plantsim > 1:
    #             plantsim = 1
    #         elif plantsim < 0:
    #             plantsim = 0
#             if plantsim:
#                 reset_lag3_states()
    elif cmdstr.lower() == "$capture":
        if noparm==1:
            print("$"+str(capture))
        else:            
            capture = int(parmstr)
            if capture > 1:
                capture = 1
            elif capture < 0:
                capture = 0
    elif cmdstr.lower() == "$streaming":
        if noparm==1:
            print("$"+str(streaming))
        else:        
            t_data = 0.0 
            datacnts = 0   
            streaming = int(parmstr)
            if streaming > 1:
                streaming = 1
            elif streaming < 0:
                streaming = 0            
    elif cmdstr.lower() == "$datasize":
        if noparm==1:
            print("$"+str(datasize))
        else:            
            datasize = int(parmstr)
            if datasize > 2000: # set maximum datasize
                datasize = 2000
            elif datasize < 10: # minimum datasize
                datasize = 10
    elif cmdstr.lower() == "$feedback":
        if noparm==1:
            print("$"+str(feedback))
        else:            
            feedback = int(parmstr)
            if feedback > 1:
                feedback = 1
            elif feedback < 0:
                feedback = 0

    elif cmdstr.lower() == "$mafilter": # turn MA4 filter off/on
        if noparm==1:
            print("$"+str(mafilter))
        else:            
            mafilter = int(parmstr)
            if mafilter > 1:
                mafilter = 1
            elif mafilter < 0:
                mafilter = 0      

    # addeed in ofc_pid_lag3.py June 2023
    elif cmdstr.lower() == "$controller":
        if noparm==1:
            print("$"+str(controller))
        else:            
            parm_tmp = int(parmstr)
            if parm_tmp > 2 or parm_tmp < 0:
                if not capture_flag:
                    print("$Bad controller choice")
            else:
                controller = parm_tmp
#                 if plantsim:
#                     reset_lag3_states()

    elif cmdstr.lower() == "$t":
        if noparm==1:
            print("$"+str(T))
        else:            
            T = float(parmstr)
            if T > 1: # set maximum T
                T = 1
            elif T < 0.001: # minimum T
                T = 0.001
            T_ms = int(1000*T)
            #a,b = lag3_init(T)
            PID_update()
            # recompute coefficients for output feedback controller
            a_int = integrator_coeff_compute()
            g_1, g_2, g_3 = leadlag_coeff_compute(ll_z, ll_p)

            
            timer.init(period=T_ms, mode=Timer.PERIODIC,
                           callback=timer_isr)
    elif cmdstr.lower() == "$kp":
        if noparm==1:
            print("$"+str(kp))
        else:            
            kp = float(parmstr)
            if kp > 100: # set maximum kp
                kp = 100
            elif kp < 0: # minimum kp
                kp = 0
            PID_update()
            # update_dashboard()

    elif cmdstr.lower() == "$ki":
        if noparm==1:
            print("$"+str(ki))
        else:            
            ki = float(parmstr)
            if ki > 100: # set maximum ki
                ki = 100
            elif ki < 0: # minimum ki
                ki = 0
            PID_update()
            #update_dashboard()

    elif cmdstr.lower() == "$kd":
        if noparm==1:
            print("$"+str(kd))
        else:            
            kd = float(parmstr)
            if kd > 100: # set maximum kd
                kd = 100
            elif kd < 0: # minimum kd
                kd = 0
            PID_update()
            #update_dashboard()

    elif cmdstr.lower() == "$kt":
        if noparm==1:
            print("$"+str(kt))
        else:            
            kt = float(parmstr)
            if kt > 100: # set maximum kt
                kt = 100
            elif kt < 0: # minimum kt
                kt = 0
            PID_update()
            #update_dashboard()

    elif cmdstr.lower() == "$wp":
        if noparm==1:
            print("$"+str(wp))
        else:            
            wp = float(parmstr)
            if wp > 10: # set maximum wp
                wp = 10
            elif wp < 0: # minimum wp
                wp = 0
            PID_update()
            #update_dashboard()

    elif cmdstr.lower() == "$wd":
        if noparm==1:
            print("$"+str(wd))
        else:            
            wd = float(parmstr)
            if wd > 10: # set maximum wd
                wd = 10
            elif wd < 0: # minimum wd
                wd = 0
            PID_update()
            #update_dashboard()

    elif cmdstr.lower() == "$n":
        if noparm==1:
            print("$"+str(N))
        else:            
            N = float(parmstr)
            if N > 200: # set maximum N
                N = 200
            elif N < 2: # minimum N
                N = 2
            PID_update()
            #update_dashboard()        
    elif cmdstr.lower() == "$autotune":
        prompt=False
        if not capture:
            print("$Autotuning starts ...")
        autotune = True
        at_ready2measure = False # clear flag
        at_time = 0.0
        at_x_old = at_x_new = 0.0
        y_max = 0.0
        cycle_cnts = 0
        if capture:
            print("datamat = np.array([")  # head of data matrix
            prompt=False # turn prompt off 
            capture_flag = True
    elif cmdstr.lower() == "$y":
        print("$"+str(y))
    elif cmdstr.lower() == "$ku": # ultimate gain from autotune
        print("$"+str(Ku))
    elif cmdstr.lower() == "$tu": # ultimate period from autotune
        print("$"+str(Tu))
    elif cmdstr.lower() == "$lsid":
        feedback = 0 # in open-loop mode
        lsid = True
        # outputting data
        print("datamat = np.array([")  # head of data matrix
        prompt=False # turn prompt off 
        capture_flag = True # output data
    elif cmdstr.lower() == "$update":   
        print("${},{},{},{},{},{},{},{},{},{},{},{},{}".format(T,
            streaming,capture,datasize,feedback,controller,kp,ki,kd,
            kt,wp,wd,N))     
    else:
        print("$Invalid command")    


def user_input():
    if prompt:
        #sys.stdout.write('\nEnter command : ')
        print("\n$Enter command : ")
    #user_str = sys.stdin.readline()
    #newline_char = sys.stdin.readline()
    user_str = input()
    cmdInt(user_str)

timer.init(period=T_ms, mode=Timer.PERIODIC,
                           callback=timer_isr)
PID_update()

while True:
    user_input()