Friday, 23 March 2018

Debugging the ESP8266 ESP-01S Relay Module

ESP8266 ESP-01S Relay Module Relay WIFI Smart Socket with ESP-01S

In a previous post I wrote about switching a 5V relay module using the ESP-12E over WiFi. Well just two days ago I spotted this delicious module for just RM26.90. It arrived today- hurrah for Internet commerce!

I powered on - and nothing happened. The red power light on the ESP-01S came on as usual, but there is none of the familiar blue flash on startup.



A little check with a multi-meter revealed that GPIO0 and CH_PD were not at the high (ie 3.3V) voltage level required for startup. A quick search on the Internet unearthed a schematic which confirmed this:

The relay module schematic has no provision for GIO0 and CH_PD tied high
Now it does not mean the module is faulty. It is possible to write a custom firmware for a working module without having to tie GPIO0 and CH_PD high. It is just a NodeMCU thing. Trouble is, the firmware in the attached ESP-01S came with NodeMCU firmware.

The modification is easy enough - I tied GPIO0 high (ie to 3.3V) using a 10K resistor as the schematic showed it was also used to control the relay. CH_PD I tied directly to 3.3V, but you are encouraged to use a 10K resistor as well.



Modifications to GPIO0 and CH_PD

And that was all it took- it powered on quite happily (I used a modified version of the Arduino IDE Blink sketch.

Working ESP-01S relay module
Here is a Youtube video of it clicking away ... Happy Trails.

Wednesday, 21 March 2018

Programming the ESP8266 ESP-01 with Arduino IDE

CH340 USB to serial TTL dongle, LM2596 buck converter and the ESP-01
Julian Hartline has an excellent post on this.

My ESP-01 from JFR Technologies turned out to be a rather ancient one - which probably explains the low price.

I used this CH340G serial TTL dongle, which also put out a 5V pin. This I used to power the ESP-01 via an LM2596 buck converter.

The main problem was with the 5V power into this whole assembly. The power required to program the ESP-01 is more than that of simply getting it to run. I had to plug it directly into my 3A externally powered USB 3.0 hub.  If I used a USB extension or a USB volt/current meter it would run up but fail to program.

Lastly it is worth repeating:
1. Select the 'Tools->Board->Generic ESP8266 Module' option in Arduino IDE
2. Set the upload speed to 9600 (most newer ESO-01 use 115200. My ESP-01 was 115200 during normal run but 9600 during program upload
2. Pull down GPIO0
3. Reset the ESP-01 by pulling down RST then releasing. The blue blinkenlight should flash.
4. Launch the upload 'Sketch->Upload'

Happy Trails.

Tuesday, 20 March 2018

IoT Relay/Switch using the ESP8266 NodeMCU ESP-12E Lua V3 and Arduino IDE

IoT Switch: From top: 5V relay PCB, Level Translator PCB and ESP-12E
As mentioned in an earlier post, lighting up a LED is very similar to controlling a relay. In place of the relay, we use a relay PCB with an optically-isolated input. I bought mine for RM9.99 from here.

5V opto-isolated Relay PCB
Since the ESP8266 ESP-12E is a 5V device, we need to translate its output to 5V. I am usually inclined to use a 1.8V zener diode like the TZS4678-GS08, costing some RM1.14. However an Arduino-type 4-channel  level converter is only RM1.35.

4-Channel Logic Level Converter
Unlike the resistor network or the zener diode method, this is an active circuit and uses the MOSFET BSS138:


There is a full explanation on the schematic here.

The wiring is quite straightforward:

ESP-12E    Level Converter   2-Channel Relay
3.3V           LV             HV        5V
GND          GND         GND      GND
D6              LV1           HV1      IN1
D7              LV2           HV2      IN2

Top wiring to ESP-12E, bottom wiring to 5V Relay PCB
The program, a Lua 'sketch' for the Arduino IDE, is much the same as the last post, tweaked a little to add a second channel. The only fiddle here is if we used D5, it seems to interfere with the programming of the ESP-12E via its USB serial port. If you do use D5, simply disconnect the level translator from the ESP-12E before you program it.

/*
 *  This sketch demonstrates how to set up a simple HTTP-like server.
 *  The server will set a GPIO pin depending on the request
 *    http://server_ip:8080/gpio/0 will set the GPIO2 low,
 *    http://server_ip:8080/gpio/1 will set the GPIO2 high
 *  server_ip is the IP address of the ESP8266 module, will be
 *  printed to Serial when the module is connected.

static const uint8_t D0 = 16;
static const uint8_t D1 = 5;
static const uint8_t D2 = 4;
static const uint8_t D3 = 0;
static const uint8_t D4 = 2;
static const uint8_t D5 = 14;
static const uint8_t D6 = 12;
static const uint8_t D7 = 13;
static const uint8_t D8 = 15;
static const uint8_t D9 = 3;
static const uint8_t D10 = 1;
*/


#include <ESP8266WiFi.h>

const char* ssid = "YourAcessPoint";
const char* password = "YourSecretPassword";

// Create an instance of the server
// specify the port to listen on as an argument
WiFiServer server(8080);

void setup() {
  Serial.begin(115200);
  delay(10);

  // prepare GPIO
  pinMode(D6, OUTPUT);
  pinMode(D7, OUTPUT);
  digitalWrite(D6, HIGH);
  digitalWrite(D7, HIGH);
  Serial.println("Relays off");

  // Connect to WiFi network
  Serial.println();
  Serial.print("Connecting to ");
  Serial.println(ssid);

  WiFi.mode(WIFI_STA);
  WiFi.begin(ssid, password);

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("");
  Serial.println("WiFi connected");

  // Start the server
  server.begin();
  Serial.println("Server started");

  // Print the IP address
  Serial.println(WiFi.localIP());
}

int val = 1;
int val2 = 1;

void loop() {
  // Check if a client has connected
  WiFiClient client = server.available();
  if (!client) {
    return;
  }

  // Wait until the client sends some data
  Serial.println("new client");
  while(!client.available()){
    delay(1);
  }

  // Read the first line of the request
  String req = client.readStringUntil('\r');
  Serial.println(req);
  client.flush();

  // Match the request
  String s = "";
  // Prepare the response
  Serial.print("Input string is ");
  Serial.println(req);
  if (req.indexOf("/D6/0") != -1) {
    val = 0;
    s = "HTTP/1.1 200 OK\r\nContent-Type: text/html\r\n\r\n<!DOCTYPE HTML>\r\n<html>\r\nD6 is now ";
    s += (val)?"high":"low";
    s += "</html>\n";
  }
  else if (req.indexOf("/D6/1") != -1) {
    val = 1;
    s = "HTTP/1.1 200 OK\r\nContent-Type: text/html\r\n\r\n<!DOCTYPE HTML>\r\n<html>\r\nD6 is now ";
    s += (val)?"high":"low";
    s += "</html>\n";
  }
  else if (req.indexOf("/D7/0") != -1) {
    val2 = 0;
    s = "HTTP/1.1 200 OK\r\nContent-Type: text/html\r\n\r\n<!DOCTYPE HTML>\r\n<html>\r\nD7 is now ";
    s += (val2)?"high":"low";
    s += "</html>\n";
  }
  else if (req.indexOf("/D7/1") != -1) {
    val2 = 1;
    s = "HTTP/1.1 200 OK\r\nContent-Type: text/html\r\n\r\n<!DOCTYPE HTML>\r\n<html>\r\nD7 is now ";
    s += (val2)?"high":"low";
    s += "</html>\n";
  }
  else if (req.indexOf("/index.html") != -1) {
    s = "HTTP/1.1 200 OK\r\nContent-Type: text/html\r\n\r\n<!DOCTYPE HTML>\r\n<html>\r\nHello, world.</html>\n";
  }
  else if (req.indexOf("/favicon.ico") != -1) {
    Serial.println("End of command");
    client.stop();
  }

  else {
    s = "HTTP/1.1 200 OK\r\nContent-Type: text/html\r\n\r\n<!DOCTYPE HTML>\r\n<html>\r\nInvalid request: ";
    s += req;
    s += "</html>\n";
    Serial.println("invalid request");
    Serial.println(req);
    client.print(s);
    delay(10);
    client.stop();
    return;
  }

  // Set GPIO2 according to the request
  if (val == 0)
    digitalWrite(D6, LOW);
  if (val == 1)
    digitalWrite(D6, HIGH);
  if (val2 == 0)
    digitalWrite(D7, LOW);
  if (val2 == 1)
    digitalWrite(D7, HIGH);

  client.flush();

  // Send the response to the client
  client.print(s);
  delay(1);
  Serial.println("Client disonnected");

  // The client will actually be disconnected
  // when the function returns and 'client' object is destroyed
}

As before, you turn on the first relay using:
http://yourIPaddress/D6/0

And off using:
http://yourIPaddress/D6/1

The commands for the second relay are:
http://yourIPaddress/D7/0
http://yourIPaddress/D7/1

The total cost of the parts was something like RM21.90 + RM9.99 + RM1.35 or RM33.24, not counting the 5V power supply and  the various bits of wires and connectors.

This is very similar to the Sonoff ITEAD IoT switch which sells for only RM30.84:

Sonoff ITEAD
There you have it: your DIY IoT switch actually sets you back some RM2.40. But as we shall see later, the Sonoff, among others, has some serious security problems, like the Krack exploit. Rolling our own IoT relay switch is the first step to taking control of our IoT security, rather than relying on the vendors' updates, both of the firmware and the accompanying app.

You can actually upgrade the Sonoff firmware yourself. Happy trails.  

Saturday, 10 March 2018

SPI Master & Slave Programs with the ESP8266 NodeMCU ESP-12E Lua V3 and Arduino IDE

ESP-12E as SPI Master (top) and SPI Slave (bottom)
After learning how to program the ESP8266 using the Arduino IDE, I thought it might be a good idea to interface the ESP8266 with Arduino-family devices. There are plenty of articles in the Web on interfacing the ESP8266 with Arduino CPUs like the Uno but comparatively few on interfacing to Arduino non-CPU PCBs.

PCBs like this relay boards are easy to interface to; you use the same method as the blinking LED sketch in my last post.
This 5V Arduino relay module costs as little as RM5

But other PCBs like this MAX7219 LED 7-segment Display costs a mere RM9.60 and uses the SPI or Serial Peripheral Interface:

MAX7219 LED 7-segment display module
 Quite a few PCBs use the I2C interface, including this delicious RM5.90 realtime clock:

PCF8563T Realtime Clock

SPI involves a master device and a slave device. I used an ESP-12E for both. The master code from the Arduino IDE "Examples->SPISlave->SPISlave_SafeMaster" menu works and is reproduced here as the code tends to change from version to version:

/*
    SPI Safe Master Demo Sketch
    Connect the SPI Master device to the following pins on the esp8266:

    GPIO    NodeMCU   Name  |   Uno
   ===================================
     15       D8       SS   |   D10
     13       D7      MOSI  |   D11
     12       D6      MISO  |   D12
     14       D5      SCK   |   D13

    Note: If the ESP is booting at a moment when the SPI Master has the Select line HIGH (deselected)
    the ESP8266 WILL FAIL to boot!
    This sketch tries to go around this issue by only pulsing the Slave Select line to reset the command
    and keeping the line LOW all other time.

*/
#include <SPI.h>

class ESPSafeMaster
{
private:
    uint8_t _ss_pin;
    void _pulseSS()
    {
        digitalWrite(_ss_pin, HIGH);
        delayMicroseconds(5);
        digitalWrite(_ss_pin, LOW);
    }
public:
    ESPSafeMaster(uint8_t pin):_ss_pin(pin) {}
    void begin()
    {
        pinMode(_ss_pin, OUTPUT);
        _pulseSS();
    }

    uint32_t readStatus()
    {
        _pulseSS();
        SPI.transfer(0x04);
        uint32_t status = (SPI.transfer(0) | ((uint32_t)(SPI.transfer(0)) << 8) | ((uint32_t)(SPI.transfer(0)) << 16) | ((uint32_t)(SPI.transfer(0)) << 24));
        _pulseSS();
        return status;
    }

    void writeStatus(uint32_t status)
    {
        _pulseSS();
        SPI.transfer(0x01);
        SPI.transfer(status & 0xFF);
        SPI.transfer((status >> 8) & 0xFF);
        SPI.transfer((status >> 16) & 0xFF);
        SPI.transfer((status >> 24) & 0xFF);
        _pulseSS();
    }

    void readData(uint8_t * data)
    {
        _pulseSS();
        SPI.transfer(0x03);
        SPI.transfer(0x00);
        for(uint8_t i=0; i<32; i++) {
            data[i] = SPI.transfer(0);
        }
        _pulseSS();
    }

    void writeData(uint8_t * data, size_t len)
    {
        uint8_t i=0;
        _pulseSS();
        SPI.transfer(0x02);
        SPI.transfer(0x00);
        while(len-- && i < 32) {
            SPI.transfer(data[i++]);
        }
        while(i++ < 32) {
            SPI.transfer(0);
        }
        _pulseSS();
    }

    String readData()
    {
        char data[33];
        data[32] = 0;
        readData((uint8_t *)data);
        return String(data);
    }

    void writeData(const char * data)
    {
        writeData((uint8_t *)data, strlen(data));
    }
};

ESPSafeMaster esp(SS);

void send(const char * message)
{
    Serial.print("Master: ");
    Serial.println(message);
    esp.writeData(message);
    delay(10);
    Serial.print("Slave: ");
    Serial.println(esp.readData());
    Serial.println();
}

void setup()
{
    Serial.begin(115200);
    SPI.begin();
    esp.begin();
    delay(1000);
    send("Hello Slave!");
}

void loop()
{
    delay(1000);
    send("Are you alive?");
}

Unfortunately the "Examples->SPISlave->SPISlave_Test" did not work for me. The Slave could read the master but its reply seems corrupted. Luckily I found a working version in the ESP8266 Community Forum:

/*
    SPI Slave Demo Sketch
    Connect the SPI Master device to the following pins on the esp8266:

    GPIO    NodeMCU   Name  |   Uno
  ===================================
     15       D8       SS   |   D10
     13       D7      MOSI  |   D11
     12       D6      MISO  |   D12
     14       D5      SCK   |   D13

    Note: If the ESP is booting at a moment when the SPI Master has the Select li
ne HIGH (deselected)
    the ESP8266 WILL FAIL to boot!
    See SPISlave_SafeMaster example for possible workaround

*/

#include "SPISlave.h"

void setup()
{
    Serial.begin(115200);
    Serial.setDebugOutput(true);
    Serial.println();

    // data has been received from the master. Beware that len is always 32
    // and the buffer is autofilled with zeroes if data is less than 32 bytes long
    // It's up to the user to implement protocol for handling data length
    SPISlave.onData([](uint8_t * data, size_t len) {
        String message = String((char *)data);
        char answer[33];
        if(message.equals("Hello Slave!")) {
            strcpy(answer, "Hello Master!");
        } else if(message.equals("Are you alive?")) {
            sprintf(answer, "Alive for %u seconds!", millis() / 1000);
        } else {
            strcpy(answer, "Say what?");
        }
        SPISlave.setData(answer);
        Serial.printf("Question: %s\Answer: %s\n", (char *)data, answer);
    });

    // The master has read out outgoing data buffer
    // that buffer can be set with SPISlave.setData
    SPISlave.onDataSent([]() {
        Serial.println("Answer Sent");
    });

    // status has been received from the master.
    // The status register is a special register that bot the slave and the master can write to and read from.
    // Can be used to exchange small data or status information
    SPISlave.onStatus([](uint32_t data) {
        Serial.printf("Status: %u\n", data);
        SPISlave.setStatus(millis()); //set next status
    });

    // The master has read the status register
    SPISlave.onStatusSent([]() {
        Serial.println("Status Sent");
    });

    // Setup SPI Slave registers and pins
    SPISlave.begin();

    // Additional setting to have MISO change on falling edge
    SPI1C2 |= 1 << SPIC2MISODM_S;

    // Set the status register (if the master reads it, it will read this value)
    SPISlave.setStatus(millis());

    // Sets the data registers. Limited to 32 bytes at a time.
    // SPISlave.setData(uint8_t * data, size_t len); is also available with the same limitation
    SPISlave.setData("Ask me a question!");
}

void loop() {}

The two ESP-12E, master and slave are wired thus:

As per the comments in the two sketches, the ESP-12E pin assignments are:

                  Master               Slave
              D8       SS      -   SS          D8
              D7      MOSI  -   MOSI    D7
              D6      MISO  -   MISO    D6
              D5      SCK    -   SCK      D5

I plugged both into the same laptop, and the slave came up as /dev/ttyUSB0 and the master /dev/ttyUSB1. By clicking on "Tools->Port" I could switch between the two serial ports and program the master and slave in turn.

When working correctly you should get the following output from the Master's Serial Monitor:

Master: Are you alive?
Slave: Alive for 44 seconds!

Master: Are you alive?
Slave: Alive for 45 seconds!

Master: Are you alive?
Slave: Alive for 46 seconds!

Master: Are you alive?
Slave: Alive for 47 seconds!

Master: Are you alive?
Slave: Alive for 48 seconds!

Now if you flipped over to /dev/ttyUSB0 and relaunched the Serial Monitor, you should get:

Question: Are you alive?Answer: Alive for 44 seconds!
Answer Sent
Question: Are you alive?Answer: Alive for 45 seconds!
Answer Sent
Question: Are you alive?Answer: Alive for 46 seconds!
Answer Sent
Question: Are you alive?Answer: Alive for 47 seconds!
Answer Sent

There you have it, SPI communication using the ESP8266 and Arduino IDE. 

Happy Trails.