# Project#2 - Sending and Receiving Data!
# Information - In this project, we're going to send data to the RPInoRPI and wait for a response.
# The RPInoRPI is waiting specifically for a value of 53, which is the ASCII representation of the decimal of 5
# When the RPInoRPI receives 53ASCII/5DEC, it will say 'Waving back" on the LCD.
import time    # The 'time' module is included with pycharm and allows for us to create delays.
import serial  # The 'serial' or 'pyserial' module needs to be imported.  See the project video for more info.
# The first thing that we need to do is to talk to our RPInoRPI.

try:  # Try to establish communication with the RPInoRPI board.  if successful, only the 'try:' will be executed
    MCU = serial.Serial(port='COM10', baudrate=115200, timeout=1)  # Notice the timeout being 1 second.
    # More on this timeout later.
    time.sleep(5)  # Wait five seconds.  Why five seconds?  The first communication gets screwy without this delay
except:  # If communication with the RPInoRPI could not be established, then perform the following instead:
    print('System Locked - Cannot communicate with MCU.  Close this program, then reconnect to MCU and restart program')
    while True:  # Forever loop.  Close the program and start again.  Check connection to the RPInoRPI
        pass  # Do nothing

def slicer(value): # This function takes the returned value from the RPInoRPI and formats it.
    # What do I mean? The RPInoRPI returns values that look like this: b'5'.
    # So what?  So we need to change that string value into a number for comparison.
    value = value.replace('b','')  # We've received value, which looks like b'5'.  Replace 'b' with nothing.
    # value does from looking like b'5' to '5'
    value = value.replace("'",'')  # Remove all ' from value.  Now we're left with 5
    value = int(value)             # At this point value is still a string.  int changes it into a comparable number =D
    return value # This is the end of this function.  The original value was an unusable string.  Now a usable number!


# This function serves to send a request to the MCU and wait for returned data
def write_read(x):
    MCU.write(bytes(x, 'utf-8'))  # Unicode Transformation Format - 8 bits.  Write an 8-bit value to the MCU
    global data                   # Set as a global varible
    data = MCU.readline()  # Wait for a response from the MCU, and store the returned value in 'data'
    return data   # Return the data to the main code

# Main Code
x = 0  # Create a variable named x and set it to 0
counter = 0 # Create a variable named 'counter' and set it to 0
while True:  # Run the following code until you close the program (loop forever)
    x = str(counter) # x now equals the string value in counter.  Counter is an integer. We can't send integers.
    print('Sending: ' + x)   # print: Sending: (whatever value x equals)
    value = write_read(x)    # call the write_read function and send 'x' along with it. We can only send string data
    print('Returned Value = ' + str(value))  # Concatenate the string + the string version of 'value' together and print
    value = slicer(str(value))  # Less complicated than it looks.  send 'value' to the slicer function in string form
    print('New number after slicer function = ' + str(value)) # Print the sliced string>number
    if value == 5:              # The returned 'value' after being sent to the slicer() function is a number.
        print('The RPInoRPI just waved back!')  # If said number is 5, print this.
    counter = counter + 1  # Increment counter. Or rather, add 1 to counter.  Counter is an integer. A while number.
    if counter == 10:      # If counter is 10, reset to 0.  We will send values 0 through 9.
        counter = 0        # Only set counter to 0 when counter equals 10
    time.sleep(0.2)        # Wait for 0.2 seconds then start over

# This is the end of the second project.  I think we did a good job ob building on project#1
# The timeout when connecting to the MCU... This is needed to save the returned value of the first transmission.
# Try changing the timeout to 0.1 and run the program.  You'll see that the first returned value is:
# Returned Value = b'', and not Returned Value = b'0', which is garbage.  We'll work around this in an upcoming project
# You've also been introduced to the slicer function, which removes some string data from the received RPInoRPI data.
# It also changes the sliced data into a number 'int' so that we can compare it to other numbers.
# Changing strings into numbers, and numbers into strings is important.  Slicing up and formatting strings is important.
# Stay tuned for project#3!