Connecting a Sense HAT to Watson IoT using Node-RED - https://developer.ibm.com/recipes/tutorials/connecting-a-sense-hat-to-watson-iot-using-node-red/

Step 3 - Marble Maze Function Node v1.json

[{"id":"479b30f5.0d2bb","type":"function","z":"7756eff1.08d0a","name":"Marble Maze","func":"// A Function to generate a new goal position\nfunction updateGoal() {\n do {\n goalX = Math.floor(Math.random()*7)+1;\n goalY = Math.floor(Math.random()*7)+1;\n } while(checkWall(goalX,goalY));\n \n flow.set('goalX',goalX);\n flow.set('goalY',goalY); \n}\n\n// Generate 'walls' - 10 randomly placed blocks\nfunction generateWalls() {\n walls = [];\n for (var i=0;i<10;i++) {\n var wx = 0;\n var wy = 0;\n do {\n wx = Math.floor(Math.random()*8);\n wy = Math.floor(Math.random()*8);\n } while(wx === x && wy === y);\n walls.push({x:wx,y:wy});\n }\n flow.set('walls',walls);\n}\n\n// Check whether a given position collides with any of the walls\nfunction checkWall(x,y) {\n for (var i=0;i<walls.length;i++) {\n if (walls[i].x === x && walls[i].y === y) {\n return true;\n }\n }\n return false;\n}\n\n// Retrieve the current player positions from local context\nvar x = context.get('x');\nvar y = context.get('y');\n\n// Retrieve the current goal position from flow context\nvar goalX = flow.get('goalX');\nvar goalY = flow.get('goalY');\n\n// Retrieve the current walls from flow context\nvar walls = flow.get('walls');\n\n// Generate new walls if needed\nif (!walls) {\n generateWalls();\n}\n\n// Generate a new goal if needed\nif (isNaN(goalX) || isNaN(goalY)) {\n updateGoal();\n}\n\n\nvar moved = false;\nvar ox = x;\nvar oy = y;\n\n// Initialise the player position\nif (isNaN(x) || isNaN(y)) {\n ox = 3;\n oy = 3;\n x = 3;\n y = 3;\n moved = true;\n} else {\n // Retrieve the current roll & pitch from the message\n // arriving from the SenseHAT\n var roll = msg.payload.orientation.roll;\n var pitch = msg.payload.orientation.pitch;\n\n // Move the player based on tilt, ensuring it stays\n // within the bounds of the screen\n var sensitivity = 7;\n if (roll > sensitivity && roll < 90) {\n y += 1;\n moved = true;\n if (y > 6) { y = 7; }\n } else if (roll < 360-sensitivity && roll > 270) {\n y -= 1;\n moved = true;\n if (y < 1) { y = 0; }\n }\n if (pitch > sensitivity && pitch < 90) {\n x -= 1;\n moved = true;\n if (x < 1) { x = 0; }\n } else if (pitch < 360-sensitivity && pitch > 270) {\n x += 1;\n moved = true;\n if (x > 6) { x = 7; }\n }\n // If the resultant position hits a wall, go back to\n // where it started\n if (checkWall(x,y)) {\n x = ox;\n y = oy;\n }\n}\n\n// Store the new player position\ncontext.set('x',x);\ncontext.set('y',y);\n\nif (moved) {\n // If the player is on the goal, generate a new set of\n // walls and goal position\n if (x === goalX && y === goalY) {\n generateWalls();\n updateGoal();\n // Blank the display\n msg.payload = \"*,*,off,\";\n } else {\n // Blank the old position of the player\n msg.payload = ox+\",\"+oy+\",off,\";\n }\n // Draw each of the walls\n for (var i =0;i<walls.length;i++) {\n msg.payload += walls[i].x+\",\"+walls[i].y+\",green,\";\n }\n // Draw the goal and player position\n msg.payload += goalX+\",\"+goalY+\",blue,\"+x+\",\"+y+\",red\";\n\n // Pass the message on to the SenseHAT Out node\n return msg;\n}\n\n// Nothing has moved so no need to update screen - return nothing\nreturn null;","outputs":"1","noerr":0,"x":877,"y":226,"wires":[[]]}] 

Step 5 - Marble Maze Function Node v2.json

[{"id":"68ae11d8.30a5b","type":"function","z":"7756eff1.08d0a","name":"Marble Maze","func":"// A Function to generate a new goal position\nfunction updateGoal() {\n do {\n goalX = Math.floor(Math.random()*7)+1;\n goalY = Math.floor(Math.random()*7)+1;\n } while(checkWall(goalX,goalY));\n \n flow.set('goalX',goalX);\n flow.set('goalY',goalY); \n}\n\n// Generate 'walls' - 10 randomly placed blocks\nfunction generateWalls() {\n walls = [];\n for (var i=0;i<10;i++) {\n var wx = 0;\n var wy = 0;\n do {\n wx = Math.floor(Math.random()*8);\n wy = Math.floor(Math.random()*8);\n } while(wx === x && wy === y);\n walls.push({x:wx,y:wy});\n }\n flow.set('walls',walls);\n}\n\n// Check whether a given position collides with any of the walls\nfunction checkWall(x,y) {\n for (var i=0;i<walls.length;i++) {\n if (walls[i].x === x && walls[i].y === y) {\n return true;\n }\n }\n return false;\n}\n\n// Retrieve the current player positions from local context\nvar x = context.get('x');\nvar y = context.get('y');\n\n// Retrieve the current goal position from flow context\nvar goalX = flow.get('goalX');\nvar goalY = flow.get('goalY');\n\n// Retrieve the current walls from flow context\nvar walls = flow.get('walls');\n\n// Generate new walls if needed\nif (!walls) {\n generateWalls();\n}\n\n// Generate a new goal if needed\nif (isNaN(goalX) || isNaN(goalY)) {\n updateGoal();\n}\n\n\nvar moved = false;\nvar ox = x;\nvar oy = y;\n\n// Initialise the player position\nif (isNaN(x) || isNaN(y)) {\n ox = 3;\n oy = 3;\n x = 3;\n y = 3;\n moved = true;\n} else {\n // Retrieve the current roll & pitch from the message\n // arriving from the SenseHAT\n var roll = msg.payload.orientation.roll;\n var pitch = msg.payload.orientation.pitch;\n\n // Move the player based on tilt, ensuring it stays\n // within the bounds of the screen\n var sensitivity = 7;\n if (roll > sensitivity && roll < 90) {\n y += 1;\n moved = true;\n if (y > 6) { y = 7; }\n } else if (roll < 360-sensitivity && roll > 270) {\n y -= 1;\n moved = true;\n if (y < 1) { y = 0; }\n }\n if (pitch > sensitivity && pitch < 90) {\n x -= 1;\n moved = true;\n if (x < 1) { x = 0; }\n } else if (pitch < 360-sensitivity && pitch > 270) {\n x += 1;\n moved = true;\n if (x > 6) { x = 7; }\n }\n // If the resultant position hits a wall, go back to\n // where it started\n if (checkWall(x,y)) {\n x = ox;\n y = oy;\n }\n}\n\n// Store the new player position\ncontext.set('x',x);\ncontext.set('y',y);\n\nif (moved) {\n var eventMsg = null;\n \n // If the player is on the goal, generate a new set of\n // walls and goal position\n if (x === goalX && y === goalY) {\n generateWalls();\n updateGoal();\n // Blank the display\n msg.payload = \"*,*,off,\";\n eventMsg = {\n payload: {\n x: goalX,\n y: goalY\n }\n };\n } else {\n // Blank the old position of the player\n msg.payload = ox+\",\"+oy+\",off,\";\n }\n // Draw each of the walls\n for (var i =0;i<walls.length;i++) {\n msg.payload += walls[i].x+\",\"+walls[i].y+\",green,\";\n }\n // Draw the goal and player position\n msg.payload += goalX+\",\"+goalY+\",blue,\"+x+\",\"+y+\",red\";\n\n // Pass the message on to the SenseHAT Out node\n return [msg,eventMsg];\n}\n\n// Nothing has moved so no need to update screen - return nothing\nreturn null;","outputs":"2","noerr":0,"x":290,"y":60,"wires":[["4255b5b7.9dfa3c"],["5d660aa0.db3394"]]}] 

Step 7 - Generate Maze Function Node.json

[{"id":"be1a48ed.8739a8","type":"function","z":"8df0e45e.720f18","name":"Generate Maze","func":"var x = msg.payload.d.x;\nvar y = msg.payload.d.y;\nvar goalX;\nvar goalY;\n\ndo {\n goalX = Math.floor(Math.random()*7)+1;\n goalY = Math.floor(Math.random()*7)+1;\n} while(goalX === x && goalY === y);\n\nvar walls = [];\nfor (var i=0;i<10;i++) {\n var wx = 0;\n var wy = 0;\n do {\n wx = Math.floor(Math.random()*8);\n wy = Math.floor(Math.random()*8);\n } while((wx === x && wy === y)||(goalX === wx && goalY === wy));\n walls.push({x:wx,y:wy});\n}\n\n\nmsg.payload = JSON.stringify({\n goal: {\n x: goalX,\n y: goalY\n },\n walls: walls\n})\nreturn msg;","outputs":1,"noerr":0,"x":536,"y":360,"wires":[["24e34620.c8902a"]]}]

Step 8 - Change Node.json

[{"id":"87f42900.93a7d8","type":"change","z":"7756eff1.08d0a","name":"","rules":[{"t":"set","p":"goalX","pt":"flow","to":"payload.goal.x","tot":"msg"},{"t":"set","p":"goalY","pt":"flow","to":"payload.goal.y","tot":"msg"},{"t":"set","p":"walls","pt":"flow","to":"payload.walls","tot":"msg"},{"t":"set","p":"refresh","pt":"msg","to":"true","tot":"bool"}],"action":"","property":"","from":"","to":"","reg":false,"x":260,"y":120,"wires":[["68ae11d8.30a5b"]]}]

Step 8 - Marble Maze Function Node v3.json

[{"id":"68ae11d8.30a5b","type":"function","z":"7756eff1.08d0a","name":"Marble Maze","func":"// Check whether a given position collides with any of the walls\nfunction checkWall(x,y) {\n for (var i=0;i<walls.length;i++) {\n if (walls[i].x === x && walls[i].y === y) {\n return true;\n }\n }\n return false;\n}\n\nif (msg.topic === \"joystick\" && msg.payload.key === \"ENTER\" && msg.payload.state === 1) {\n // Reset everything if needed\n msg.refresh = true;\n flow.set('goalX',null);\n flow.set('goalY',null);\n flow.set('walls',[]);\n \n}\n\n// Retrieve the current player positions from local context\nvar x = context.get('x');\nvar y = context.get('y');\n\n// Retrieve the current goal position from flow context\nvar goalX = flow.get('goalX');\nvar goalY = flow.get('goalY');\n\n// Retrieve the current walls from flow context\nvar walls = flow.get('walls')||[];\n\n// Generate a new goal if needed\nif (goalX===null || goalY===null) {\n goalX = Math.floor(Math.random()*7)+1;\n goalY = Math.floor(Math.random()*7)+1;\n flow.set('goalX',goalX);\n flow.set('goalY',goalY);\n msg.refresh = true;\n}\n\n\nvar moved = false;\nvar ox = x;\nvar oy = y;\n\n// Initialise the player position\nif (isNaN(x) || isNaN(y)) {\n ox = 3;\n oy = 3;\n x = 3;\n y = 3;\n moved = true;\n} else {\n if (msg.payload.orientation) {\n // Retrieve the current roll & pitch from the message\n // arriving from the SenseHAT\n var roll = msg.payload.orientation.roll;\n var pitch = msg.payload.orientation.pitch;\n \n // Move the player based on tilt, ensuring it stays\n // within the bounds of the screen\n var sensitivity = 7;\n if (roll > sensitivity && roll < 90) {\n y += 1;\n moved = true;\n if (y > 6) { y = 7; }\n } else if (roll < 360-sensitivity && roll > 270) {\n y -= 1;\n moved = true;\n if (y < 1) { y = 0; }\n }\n if (pitch > sensitivity && pitch < 90) {\n x -= 1;\n moved = true;\n if (x < 1) { x = 0; }\n } else if (pitch < 360-sensitivity && pitch > 270) {\n x += 1;\n moved = true;\n if (x > 6) { x = 7; }\n }\n // If the resultant position hits a wall, go back to\n // where it started\n if (checkWall(x,y)) {\n x = ox;\n y = oy;\n }\n }\n}\n\n// Store the new player position\ncontext.set('x',x);\ncontext.set('y',y);\n\nif (moved || msg.refresh) {\n var eventMsg = null;\n \n // If the player is on the goal, generate a new set of\n // walls and goal position\n if (x === goalX && y === goalY) {\n walls = [];\n flow.set('walls',walls);\n // Blank the display\n eventMsg = {\n payload: {\n x: goalX,\n y: goalY\n }\n };\n goalX = -1;\n goalY = -1;\n flow.set('goalX',goalX);\n flow.set('goalY',goalY);\n \n }\n msg.payload = \"*,*,off,\";\n // Draw each of the walls\n for (var i =0;i<walls.length;i++) {\n msg.payload += walls[i].x+\",\"+walls[i].y+\",green,\";\n }\n if (goalX !== -1 && goalY !== -1) {\n msg.payload += goalX+\",\"+goalY+\",blue,\";\n }\n // Draw the goal and player position\n msg.payload += x+\",\"+y+\",red\";\n\n // Pass the message on to the SenseHAT Out node\n return [msg,eventMsg];\n}\n\n// Nothing has moved so no need to update screen - return nothing\nreturn null;","outputs":"2","noerr":0,"x":470,"y":60,"wires":[["4255b5b7.9dfa3c"],["5d660aa0.db3394"]]}]