Tessel 2: wifi measuring and power demonstration with replacement components Raw

report.md

• Subject Tessels

  • ava: T2 as presently shipping
  • dolores: T2 testing new components

• Tests

  • Wifi Strength

    • Wifi measuring @ 3m from router (10 measurements)

      Board	Source	Avg dBm	Avg Quality
      ava	USB to MBP	-41	69/70
      ava	USB to 5V 2400mAh battery (fully charged)	-43	67/70
      ava	USB to 5V 1000mAh wall wart	-39	70/70
      dolores	USB to MBP	-37	70/70
      dolores	USB to 5V 2400mAh battery (fully charged)	-41	69/70
      dolores	USB to 5V 1000mAh wall wart	-41	69/70

    • Wifi measuring @ 5m from router (10 measurements)

      Board	Source	Avg dBm	Avg Quality
      ava	USB to MBP	-41	69/70
      ava	USB to 5V 2400mAh battery (fully charged)	-42	69/70
      ava	USB to 5V 1000mAh wall wart	-42	70/70
      dolores	USB to MBP	-40	70/70
      dolores	USB to 5V 2400mAh battery (fully charged)	-42	70/70
      dolores	USB to 5V 1000mAh wall wart	-43	70/70

    • Wifi measuring @ 5m horizontal, 3.1m vertical, with steel staircase between router and Tessel (10 measurements)

      Board	Source	Avg dBm	Avg Quality
      ava	USB to 5V 2400mAh battery (fully charged)	-59	49/70
      dolores	USB to 5V 2400mAh battery (fully charged)	-56	55/70

    • Measurment program:

      "use strict";
      
      let cp = require("child_process");
      let iterations = -1;
      let results = [];
      
      const MAX_MEASUREMENTS = 10;
      const COMMAND = "iwinfo wlan0 scan";
      const NETWORK = "Bocoup";
      
      function capturedBm(result) {
        let cells = result.split("\nCell");
        return cells.reduce((captured, cell) => {
          if (captured) {
            return captured;
          }
      
          let isMeasuredNetwork = cell.includes(`ESSID: "${NETWORK}"`);
          let rsignal = /Signal: (.*) dBm/;
      
          if (isMeasuredNetwork) {
            let parsed = rsignal.exec(cell);
      
            if (parsed.length === 2) {
              captured = Number(parsed[1]);
            }
          }
          return captured;
        }, null);
      }
      
      function run() {
        if (++iterations === MAX_MEASUREMENTS) {
          console.log(`Average of ${MAX_MEASUREMENTS} measurements: `);
          console.log(results.reduce((a, b) => a + b) / results.length);
        } else {
          cp.exec(COMMAND, (error, result) => {
            results.push(capturedBm(result));
            console.log(".");
            run();
          });
        }
      }
      
      run();

  • Download

    • Download https://builds.tessel.io/t2/firmware/40b2b46a62a34b5a26170c75f7e717cea673d1eb.tar.gz (3 measurements)

      • Length: 15457068 (15M) [application/x-gzip]

        Board	Avg Seconds
        ava	19.60
        dolores	20.86

    • Measurment program:

      "use strict";
      
      const got = require("got");
      const REMOTE_TGZ_URL = "https://builds.tessel.io/t2/firmware/40b2b46a62a34b5a26170c75f7e717cea673d1eb.tar.gz";
      const MAX_MEASUREMENTS = 3;
      
      let iterations = -1;
      let results = [];
      
      function run() {
        if (++iterations === MAX_MEASUREMENTS) {
          console.log(`Average of ${MAX_MEASUREMENTS} measurements: `);
          console.log(results.reduce((a, b) => a + b) / results.length);
        } else {
          const start = Date.now();
          got.stream(REMOTE_TGZ_URL).on("data", _ => {}).on("end", () => {
            const time = Date.now() - start;
            const result = time / 1000;
            results.push(result);
            console.log(result);
            run();
          });
        }
      }
      
      run();

  • USB Port Power

    • Can switch port power on and off

      Board	Port	Outcome
      ava	0	Yes
      ava	1	Yes
      dolores	0	Yes
      dolores	1	Yes

    • Test program:

      "use strict";
      
      let port = process.argv[2];
      let ppps = require("ppps");
      
      ppps.findHubs(0x1a40, 0x0101, (error, hubs) => {
        console.log("Port: ", port);
        console.log("Powering off");
        hubs[0].port(port).control(0);
      
        setTimeout(_ => {
          console.log("Powering On");
          hubs[0].port(port).control(1);
        }, 3000);
      });

      Run as:

      t2 run ppps.js [0]
      t2 run ppps.js [1]