added NodeMCU code and documentation

docu/notes.txt

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+https://hackaday.com/2016/06/14/hackaday-prize-entry-micro-robots-for-education/
+
+https://www.adafruit.com/product/3216
+
+https://www.exp-tech.de/plattformen/robotik/roboterfahrzeuge/7673/adafruit-mini-round-robot-chassis-kit-2wd-with-dc-motors?gclid=EAIaIQobChMIrpHIq4Ke4QIVSeAYCh0LTgdWEAQYCCABEgIQcfD_BwE
+
+https://www.exp-tech.de/plattformen/robotik/roboterfahrzeuge/7898/adafruit-mini-3-layer-round-robot-chassis-kit-2wd-with-dc-motors?gclid=EAIaIQobChMIrpHIq4Ke4QIVSeAYCh0LTgdWEAQYCyABEgI76vD_BwE
+
+

docu/pin_out.txt

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+Breadboard | NodeMCU, GPIO, index | H-bridge
+-------------------------------------
+ 13        |  D0, 16, 0           | 15      # driver channel 4 input
+ 14        |  D1,  5, 1           | 10      # driver channel 3 input
+ 15        |  D2,  4, 2           |  9      # driver 3/4 enable  (pwm)
+ 16        |  D3,  0, 3           |  2      # driver channel 2 input
+ 17        |  D4,  2, 4           |  7      # driver channel 1 input
+ 20        |  D5, 14, 5           |  1      # driver 1/2 enable (pwm)
+ 26        |  GND    
+ 
+Motor example:
+ First motor:
+ GPIO16 -> HIGH (index 0)
+ GPIO05 -> LOW  (index 1) 
+ GPIO04 -> HIGH (index 2)
+
+ Second motor:
+ GPIO00 -> HIGH (index 3)
+ GPIO02 -> LOW  (index 4)
+ GPIO14 -> HIGH (index 5)
+

nodemcu_firmware/flashing_notes.txt

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+esptool.py --port /dev/ttyUSB0 write_flash -fm qio 0x00000 nodemcu-master-9-modules-2019-04-08-19-43-38-float.bin 
+

nodemcu_firmware/init.lua

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+dofile('motor.lua')
+
+cfg={}
+cfg.ssid="robot-1"
+cfg.pwd="roborally"
+wifi.ap.config(cfg)
+
+sv = net.createServer() 
+
+Peer = {}
+function Peer:create(sck)
+  local peer = {}
+  setmetatable(peer, Peer)
+  peer.buffer = {}
+  return peer
+end
+function Peer:receive(sck, data)
+  self.buffer = self.buffer .. data
+  if #self.buffer >= 4 then
+	  dir = string.byte(self.buffer,1)
+	  if dir > 127 then dir = -256+dir end 
+	  motor_dir(1, dir)
+
+	  dir = string.byte(self.buffer,2)
+	  if dir > 127 then dir = -256+dir end 
+	  motor_dir(2, dir)
+
+	  delay = string.byte(self.buffer,3) * 256 + string.byte(self.buffer, 4)
+	  tmr.delay(delay) 
+
+	  motor_dir(1, 0)
+	  motor_dir(2, 0)
+	  self.buffer = {}
+  sck:close()
+  end
+end
+
+if sv then
+-- listen to port 80 and call callback function if data is received
+  sv:listen(80,  
+function(conn)
+  peer = Peer:create(conn)
+  conn:on("receive", peer:receive(conn))
+  conn:send("robot-1 at your service")
+  end)
+end

nodemcu_firmware/motor.lua

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+motor = {}
+motor[1] = {}
+motor[1][1] = 0
+motor[1][2] = 1
+motor[1][3] = 2
+
+motor[2] = {}
+motor[2][1] = 3
+motor[2][2] = 4
+motor[2][3] = 5
+
+for i,m in ipairs(motor) do
+	for i,g in ipairs(m) do
+		gpio.mode(g, gpio.OUTPUT)
+		gpio.write(g, 1)
+	end
+end
+
+function motor_dir(m, dir)
+	if dir ~= 0 then
+		gpio.write(motor[m][3], 1)
+		gpio.write(motor[m][1], (1-dir)/2)
+		gpio.write(motor[m][2], (1+dir)/2)
+	else
+		gpio.write(motor[m][3], 0)
+	end
+end
+

nodemcu_firmware/motor.lua.1

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+motor = {}
+motor[1] = {}
+motor[1][1] = 0
+motor[1][2] = 1
+motor[1][3] = 2
+
+motor[2] = {}
+motor[2][1] = 3
+motor[2][2] = 4
+motor[2][3] = 5
+
+for i,m in ipairs(motor) do
+	for i,g in ipairs(m) do
+		gpio.mode(g, gpio.OUTPUT)
+		gpio.write(g, 1)
+	end
+end
+
+function motor_dir(m, dir)
+	if dir ~= 0 then
+		gpio.write(motor[m][3], 1)
+		gpio.write(motor[m][1], (1-dir)/2)
+		gpio.write(motor[m][2], (1+dir)/2)
+	else
+		gpio.write(motor[m][3], 0)
+	end
+end
+

nodemcu_firmware/motor.lua.2

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+motor = {}
+motor[1] = {}
+motor[1][1] = 0
+motor[1][2] = 1
+motor[1][3] = 2
+
+motor[2] = {}
+motor[2][1] = 3
+motor[2][2] = 4
+motor[2][3] = 5
+
+for i,m in ipairs(motor) do
+	for i,g in ipairs(m) do
+		gpio.mode(g, gpio.OUTPUT)
+		gpio.write(g, 1)
+	end
+end
+
+function motor_dir(m, dir)
+	if dir ~= 0 then
+		gpio.write(motor[m][3], 1)
+		gpio.write(motor[m][1], (1-dir)/2)
+		gpio.write(motor[m][2], (1+dir)/2)
+	else
+		gpio.write(motor[m][3], 0)
+	end
+end
+
+Peer = {}
+function Peer:create(sck)
+	local peer = {}
+	setmetatable(peer, Peer)
+	peer.buffer = {}
+	return peer
+end
+function Peer:receive(sck, data)
+	self.buffer = self.buffer .. data
+	if #self.buffer >= 4 then
+	
+		sck:close()
+	end
+end
+
+function(conn)
+	peer = Peer:create(conn)
+	conn:on("receive", peer:receive)
+end

nodemcu_firmware/notes.txt

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+# flashing firmware onto NodeMCU
+esptool.py --port /dev/ttyUSB0 write_flash -fm qio 0x00000 nodemcu-master-9-modules-2019-04-08-19-43-38-float.bin
+
+# connecting to NodeMCU via serial terminal
+cu -l /dev/ttyUSB0 -s 115200 dir
+
+# uploading code to NodeMCU
+nodemcu-uploader upload motor.lua
+nodemcu-uploader upload init.lua
+
+# sending data over wifi via socket
+nc 192.168.4.1 80

nodemcu_firmware/serial_terminal.txt

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+cu -l /dev/ttyUSB0 -s 115200 dir

nodemcu_firmware/upload_notes.txt

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+nodemcu-uploader upload motor.lua 
+nodemcu-uploader upload init.lua