---
title: "IoT Workshop"
author: Trygve Laugstøl \<trygvis@trygvis.io\>
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---

# What is IoT

## What is IoT

* Not "a computer connected to the internet"
    * Then it is really just another computer connected to the internet

* Must be something else
    * It is simply devices that are resource constrained
        * Usually in more than one way

* Autonomous operation, the connection might not be permanent

## IoT is just a concept

* *The Internet of Things (IoT) is the network of physical devices,
  vehicles, home appliances and other items embedded with
  electronics, software, sensors, actuators, and connectivity which
  enables these objects to connect and exchange data.*^[
  Wikipedia "Internet of Things"]

## What is an IoT Device?

::: notes

As for their definition.

What differentiates a computer from an IoT device?

:::

## What is an IoT Device?

* Constrained in (one or more of):
    * Memory
    * CPU
    * Network bandwidth and/or latency
    * Storage

## Typical IoT chips - Bluetooth 4/5

!comment
~~~
~~~
Chip     CPU      Freq RAM      Flash  Price
-------- -------- ---- -------- ------ ------
nRF52810 Cortex-M4 64 MHz    24k   192k  $1.88
High performance, entry-level Bluetooth 4/ANT/2.4GHz SoC

nRF52832 Cortex-M4F          32k   256k  $2.54
                             64k   512k  $2.59
High performance Bluetooth 4/ANT/2.4GHz SoC

nRF52840 Cortex-M4F         256k  1024k  $3.85
Advanced multi-protocol System-on-Chip Supporting: Bluetooth 5, ANT/ANT+, 802.15.4 and 2.4GHz proprietary

::: notes

All quantities are 1000 pieces

nRF51: https://www.digikey.no/products/en/rf-if-and-rfid/rf-transceiver-ics/879?k=nrf51822

nRF52832: these have different packagings, not only difference price

https://www.digikey.no/products/en/rf-if-and-rfid/rf-transceiver-ics/879?FV=1c0001%2Cffe0036f&quantity=3000&ColumnSort=1000011&page=1&k=nrf52832&pageSize=500&pkeyword=nrf52810

:::

## Typical IoT chips - Wi-Fi

Chip    CPU            Freq     ROM   RAM    Price
-----   -------        -------  ----- ------ ------
ESP8266 Tensilica L106 160 MHz    N/A ~50 kB   < $1

ESP32 - dual cpu, Wi-Fi, Bluetooth 4
ESP32-D0WDQ6 2x Xtensa @ 160MHz  $ 4.53 @ 10

::: notes

The ESP8266's RAM depends on which firmware stack is used. Physical is probably 128k or most likely 64k.

:::

## ESP8266 details - Power usage

+--------------------------+----------------+
| State                    | Current usage  |
+==========================+===============:+
| Off					   | 0.5 µA         |
+--------------------------+----------------+
| Deep sleep with RTC	   | 20 µA          |
+--------------------------+----------------+
| Light sleep (with Wi-Fi) | 1 mA           |
+--------------------------+----------------+
| Sleep with peripherials  | 15 mA          |
+--------------------------+----------------+
| TX					   | 170 mA         |
+--------------------------+----------------+

::: notes

Datasheet page 18

:::

## ESP8266 details - Arduino

https://github.com/esp8266/Arduino

# Going back to basics

## What is the internet again?

## OSI model

1. Physical Layer
1. Data Link Layer
1. Network Layer
1. Transport Layer
1. Session Layer
1. Presentation Layer
1. Application Layer


* [Wikipedia: OSI model](https://en.wikipedia.org/wiki/OSI_model)
* [Wikipedia: OSI model#Examples](https://en.wikipedia.org/wiki/OSI_model#Examples)

::: notes

Does not match the TCP/IP stack very closely.

:::

## Layer 1: Physical Layer

* 10BASE5, 10BASE2
* 10BASE-T / 100BASE-TX / 1000BASE-TX
* 802.11a/b/g/n PHY
* RS-232

::: notes

Ethernet: Hubs and switches (that act on this level) is not on it's own
layer. It is more of a implementation detail in the architecture diagram.

RS-232 signaling is used in *all* MCUs, many have several ports
available. It is extremely flexible, both used for implementing
applications and debugging. Frequently an easy way to hack embedded
devices. "USB dongles", "USB TTL" all use RS-232 signaling.

Note that this only applies to its logical signals, not voltage
levels. The signaling does not specify any max data rate, very high rates
(>= 1Mbps) is often supported.

:::


## Layer 2: Data Link Layer

* Ethernet
* WiFi
* Bluetooth
* Token Ring

## Layer 3: Network Layer

* IP
* ICMP
* IPX

## Layer 4: Transport Layer

* TCP
* UDP

## Layer 5: Session Layer

* "sockets"
* NetBIOS

## Layer 6: Presentation Layer

* SSL

::: notes

This layer is not really much used in the IP stack

:::

## Layer 7: Application Layer

* HTTP
* DNS
* MQTT
* CoAP
* (everything else..)

## Details: IP

!ifdef(REVEAL)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
![](images/ip-header.svg)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
!ifdef(BEAMER)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
!ifndef(QUICK)(![](images/ip-header.pdf))
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

::: notes

Note that the "total length" field is 16 bits, 2 bytes, it's maximum value is 64k, 65536.

:::

## Details: IP

!ifndef(QUICK)(!include(images/IP-Header_eng.tex))

!comment
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
![](images/IP-Header_eng.pdf)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

# Lecture: ESP8266 aka NodeMCU aka ESP-12

# Lecture: MQTT

## MQTT

* *Message Queuing Telemetry Transport*
* [Wikipedia: MQTT](https://en.wikipedia.org/wiki/MQTT)

## MQTT Implementations

* Mosquitto
* Eclipse Paho
* Redis with MQTT connector

## MQTT Cloud Connectors

* Cloud
	* Amazon IoT
	* Google Cloud IoT
	* Microsoft Azure IoT
	* CloudMQTT

* DIY
	* ThingMQ
	* HiveMQ

::: notes

In between are:

* self hosted
* Generic bridges

:::

# Notes

## Assignments

* Measure round trip time/latency. Measure UDP, TCP. Measure when the
  packet size is greater than the MTU

* Measure ISR timing