## RASPEBRRY PI PLOTTING SERIAL COMUNICATION OVER TTL
On this repo we are going to document the process to run a plotter by serial of a raspberry pi.

:::spoiler Code to detect changes on USB ports:

#!/usr/bin/python

# .-------------------------------------------------------------------------.
# | This program monitors for changes in 'lusb' reports and files in the    |
# | /dev directory when a USB device is connected or removed. It basically  |
# | saves having to manually run 'lsusb' and 'ls' and having to compare the |
# | results.                                                                |
# `-------------------------------------------------------------------------'

import os
import time

def GetUsbList() : return os.popen("lsusb").read().strip().split("\n")
def GetDevList() : return os.listdir("/dev")

def Changed(old, now):
  add = []
  rem = []
  for this in now:
    if not this in old:
      add.append(this)
  for this in old:
    if not this in now:
      rem.append(this)
  return add, rem

try:
  print("Monitoring for USB changes and changes in /dev directory")
  usbOld, devOld = GetUsbList(), GetDevList()
  while True:
    time.sleep(1)
    usbNow, devNow = GetUsbList(), GetDevList()
    usbAdd, usbRem = Changed(usbOld, usbNow)
    devAdd, devRem = Changed(devOld, devNow)
    if len(usbAdd) + len(usbRem) + len(devAdd) + len(devRem) > 0:
      print("-------------------")
      t = time.strftime("%Y-%m-%d %H:%M:%S - ")
      for this in usbAdd : print(t + "Added   : "      + this)
      for this in usbRem : print(t + "Removed : "      + this)
      for this in devAdd : print(t + "Added   : /dev/" + this)
      for this in devRem : print(t + "Removed : /dev/" + this)
      usbOld, devOld = usbNow, devNow
except KeyboardInterrupt:
  print("")

:::

If not, you can just use ``ls /dev/tty*`` and this should list you all USB devices connected to the raspberry pi.

One you have found the device name for serial communication, we can continue. In my case is **/dev/ttyACM0**.

___

:::spoiler **USEFULL LINKS**
https://www.seeedstudio.com/blog/2019/12/11/rs232-vs-ttl-beginner-guide-to-serial-communication/?srsltid=AfmBOopyHmfMTBT-HMNNl2oH9s7zu6fIzVYlkEmmFhWcwuwP7TMOU-b3

https://roboticsbackend.com/raspberry-pi-arduino-serial-communication/
:::

Step 1:
Hardware permissions for Serial

This should give u rights to read serial.

Step 2:
Install Python Serial library on Raspberry Pi
``python3 -m pip install pyserial``


![image](https://hackmd.io/_uploads/ryyEKqqpJg.png)


https://www.probotix.com/gcode_cheatsheet.pdf