Arduino ethernet hardware watchdog

So I have a few raspberry pis that (3 in fact!), and sometimes have them set up for remote access such as a raspberry pi webcam using the raspberry pi camera, web servers, remote power socket control, weather monitoring, energy usage – the usual geeky stuff.

Various raspberry pi projects of mine!

Anyway, sometimes the thing runs smoothly and reliably for years on end without problems (usually the less you tinker with it!), surviving power cuts and what have you. My first Model B Rev 1 Pi (thanks Dad!) is an example of these. It ran for years monitoring temperature/humidity and air pressure, before finally being shutdown due to a house move (someday i’ll have to resurrect it!).

Sometimes however, things don’t go to plan and Linux will crash or lock up, or the network interface will go down on power cuts. For instance I once wrote a script to restore the wifi connection of a pi in my GF’s locked and empty house using a lovely blackberry smartphone while sitting in a buddy’s car eating kfc chicken outside. But that’s another story! (Thanks Andy!). It usually happens right when you’re away the Pi and trying to login remotely!

I tried using the raspberry pi watchdog timer (see here: Raspberry pi Watchdog timer), but this didn’t seem to fix the problem

So I built an Arduino hardware watchdog that keeps an eye on the ping result of a host on the network, and reboots the device if it fails tor respond. IT has a 16×02 lcd to display current action/state although someday i’d like to have leds for each state instead. with a button to manually reboot.

The project utilized a remote control socket (from Maplin, RIP), an arduino uno with an ethernet shield and a 16×02 lcd shield (with pin 10 bent out to prevent issues between the ethernet shield and the lcd shield backlight) plus a 433mhz tx module and the rcswitch library.

Maplin/Wilko remote sockets, available here 

code below

/*
Ping Example

This example sends an ICMP pings every 500 milliseconds, sends the human-readable
result over the serial port.

Circuit:
Ethernet shield attached to pins 10, 11, 12, 13
433mhz tx module on pin 2
LCD on pins 8, 9, 4, 5, 6, 7

Pin 10 of the LCD bent out of socket to prevent issues caused by the backlight

created 30 Sep 2010
by Blake Foster

Modified by Garreth Tinsley

*/
const int txDataPin = 2;

#include <SPI.h>
#include <Ethernet.h>
#include <ICMPPing.h>
#include <RCSwitch.h> // for 433 tx module/remote switch control
#include <LiquidCrystal.h> // For LCD
long retrytimeout = 15L * 1000L; //recheck every 15 seconds
long cycletimeout = 120000;
long starttime;
long currtime;

bool looptwice = false;

byte mac[] = {0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED}; // max address for ethernet shield
//byte ip[] = {192,168,2,177}; // ip address for ethernet shield
IPAddress pingAddr(192, 168, 1, 2); // ip address to ping

SOCKET pingSocket = 0;

char buffer [256];
ICMPPing ping(pingSocket, (uint16_t)random(0, 255));
RCSwitch mySwitch = RCSwitch();
LiquidCrystal lcd(8, 9, 4, 5, 6, 7); // initialize the LCD library with the numbers of the interface pins

void setup()
{
lcd.begin(16, 2);
lcd.setCursor(0, 0);
lcd.print(“Rebooter 0.2”);
//0.1 it works!
//0.2 it works an is neater (lcd printing countdown, ip addr print not . after last octet, padding seconds)
lcd.setCursor(0, 1);
lcd.print(“starting…”);
Serial.begin(9600);
// start the Ethernet connection:
if (Ethernet.begin(mac) == 0) {

lcd.clear();
lcd.setCursor(0, 0);
lcd.print(“IP DHCP CONFIG”);
lcd.setCursor(0, 1);
lcd.print(“Failed! Halting.”);
// no point in carrying on, so do nothing forevermore:
while (true) {
Serial.println(“no dhcp, halted”);
delay(1000);
};
}

lcd.clear();
lcd.setCursor(0, 0);
lcd.print(“IP DHCP CONFIG”);
lcd.setCursor(0, 1);
printIPAddress();
delay(2000);

//start the rc tx module
mySwitch.enableTransmit(txDataPin);
}

void loop()
{
lcd.clear();
ICMPEchoReply echoReply = ping(pingAddr, 4);
if (echoReply.status == SUCCESS)
{
lcd.setCursor(0, 0);
lcd.print(“Ping succeeded.”);
sprintf(buffer,
“Reply[%d] from: %d.%d.%d.%d: bytes=%d time=%ldms TTL=%d”,
echoReply.data.seq,
echoReply.addr[0],
echoReply.addr[1],
echoReply.addr[2],
echoReply.addr[3],
REQ_DATASIZE,
millis() – echoReply.data.time,
echoReply.ttl);

starttime = millis();
currtime = starttime;
long prevtime = starttime;

while (currtime <= starttime + cycletimeout) {
if (currtime >= prevtime + 1000) {
//update the lcd every second
lcd.setCursor(0, 1);
lcd.print(“retest in: “);
lcdPrintSecondsQuad(((starttime + cycletimeout) – currtime) / 1000L);

//lcd.print(“s”);
prevtime = currtime;
}
delay(100);
currtime = millis();
}

}
else
{
sprintf(buffer, “Echo request failed; %d”, echoReply.status);
lcd.setCursor(0, 0);
lcd.print(“Ping failed”);

//ensure ping has failed twice consecutively
if (looptwice == true) {

lcd.setCursor(0, 1);
lcd.print(“Switching off…”);
/* See Example: TypeB two rotary */
mySwitch.switchOff(4, 4);

delay(3000);

lcd.setCursor(0, 1);
lcd.print(“Switching on…”);
mySwitch.switchOn(4, 4);

lcd.clear();
lcd.print(“Waiting 1 minute”);
lcd.setCursor(0, 1);
lcd.print(“please wait…”);
looptwice = false;
//delay(cycletimeout);

starttime = millis();
currtime = starttime;
long prevtime = starttime;

while (currtime <= starttime + cycletimeout) {
if (currtime >= prevtime + 1000) {
//update the lcd ever second
lcd.setCursor(0, 1);
lcd.print(“reteest in: “);
lcd.print(((starttime + cycletimeout) – currtime) / 1000L);
lcd.print(“s”);
prevtime = currtime;
}
delay(100);
currtime = millis();
}

}
else {
lcd.setCursor(0, 1);
lcd.print(“retest in 15s”);

looptwice = true;

starttime = millis();
currtime = starttime;
long prevtime = starttime;

while (currtime <= starttime + retrytimeout) {
if (currtime >= prevtime + 1000) {
//update the lcd ever second
lcd.setCursor(0, 1);
lcd.print(“retest in: “);
lcdPrintSecondsQuad(((starttime + cycletimeout) – currtime) / 1000L);
prevtime = currtime;
}
delay(100);
currtime = millis();
}

delay(retrytimeout);
}
}
Serial.println(buffer);
}

void printIPAddress()
{
Serial.print(“My IP address: “);
for (byte thisByte = 0; thisByte < 4; thisByte++) {
// print the value of each byte of the IP address:
lcd.print(Ethernet.localIP()[thisByte], DEC);
Serial.print(Ethernet.localIP()[thisByte], DEC);
if (thisByte < 3) { //dont dot if last octet
lcd.print(“.”);
Serial.print(“.”);
}
}

Serial.println();
}

void lcdPrintSecondsQuad(int digit)
/* A ten percent reduction in input voltage
will cause the lower bound to drop by ten.
This sketch is calibrated for ~4.9-5.1v
using the linksprite LCD shield. */
{
if (digit < 10)
{ // 9s
lcd.print(” “);
lcd.print(digit, DEC);
lcd.print(“s”);
}
else if (digit < 100)
{ // 99s // 10s
lcd.print(” “);
lcd.print(digit, DEC);
lcd.print(“s”);
}
else if (digit < 1000)
{ //999s //100s
lcd.print(digit, DEC);
lcd.print(“s”);
}
else if (digit > 999)
{ //1000s
lcd.print(digit, DEC);
}
}

Links to guides for some of the projects i’ve tried:

  • Raspberry ambilight clone for Raspbmc/OSMC (Kodi on Linux) – Hyperion Project:

    WS2812b leds providing ambilight like backwash

  • Raspberry pi hardware watchdog timer (reboot on crash using kernel module, only requires raspberry pi, no external hardware) – Raspberry pi Watchdog timer

Ps sorry this post is long and a bit rambly, it was written across a few years!

PPS if anyone knows how to get wordpress to display C++/Arduino sketches nicely with syntax highlighting etc, please let me know in the comments!

sunset photo, taken 20th april 2007 in Wales, UK.

Depression & Suicide

I wrote this as a response to an image post trying to guilt-trip people into not commiting suicide using friends and family, on reddit. The reddit OP removed his post due to criticism, so I’ve copied it here.

Here’s the thing most people don’t get about suicide.

Those who choose to kill themselves aren’t (normally) irrational. They’re making a considered option. They’re aware of the pain they’ll leave. They’re aware of the pain of the method.

Someone who chooses to commit suicide is exactly the same response as the person who chooses to jump to death from a burning building. It’s not that the suicide is a good option. It’s that staying is unbearable.

Severe depression, or severe recurrent depression the type I suffer from, is a cruel, evil disease. It eats at your joy of life, it eats at your ability to look after yourself, it eats at your ability to function day-to-day, even simple things like cooking a meal being more akin to climbing mount Everest in a wheelchair, blindfolded, with your hands tied behind your back, than anything else.

You want to help someone like me not decide in the darkest, most painful times not to die?

First, don’t try to guilt-trip them with friends and family. It won’t help, I already know all those things. I’ve already considered them. I’ve discounted them. Sometimes the suffering is just too great.

Second, be there. That friend who you’ve not heard from for a while? Phone. Suggest popping over for a cuppa tea. Suggest they come to you. Push a little. Text. Email. IM. Skype. Reach out.

Third, if you know someone is suffering, offer to listen, anytime, anywhere, anyhow, and mean it. Keep your phone on next to you, and pick it up at 3am if they call.

Forth, if someone is really bad, struggling day to day, offer real help. Not “I’m here for you” but “hey, I’m coming over Friday, we’ll watch a film and order pizza”. Or “Hey, I’m bringing over my pasta bake, and leaving it with you, I’ll pick up the dish tomorrow.”. “Hey, need any help with housework? I’m free Saturday to come help if you want?”

Finally, Accept that, even then, sometimes someone like me will be suffering too much, and it’s not about you. It’s not about your pain, that they were suffering too much, and decided enough was enough. They’re in less pain than they were before.

P.S. Vote. Vote for people who give a shit about mental health support (in the UK, NOT THE CONSERVATIVES FOR THE LOVE OF ALL THAT IS GOOD). Vote for those who care about basic medical support. Consider donating to research.

p.p.s edit; please don’t say anything along the lines of ‘why don’t you just decide to be happy?’. That doesn’t help.

But seriously, be there for your friends and family, especially if they’re being weirdly distant. You may just save a life.

Swappiness in linux

Shamelessly stolen from wikipedia because they’re thinking about removing this, as¬† “Wikipedia is not a howto”. *sigh*.

 

With kernel version 3.5 and over, as well as kernel version 2.6.32-303 and over, it is likely better to use 1 for cases where 0 used to be optimal.

To temporarily set the swappiness in Linux, write the desired value (e.g. 10) to /proc/sys/vm/swappiness using the following command, running as root user:

# Set the swappiness value as root
echo 10 > /proc/sys/vm/swappiness

# Alternatively, run this
sysctl -w vm.swappiness=10

# Verify the change
cat /proc/sys/vm/swappiness
10

# Alternatively, verify the change
sysctl vm.swappiness
vm.swappiness = 10

Permanent changes are made in /etc/sysctl.conf via the following configuration line (inserted, if not present):

vm.swappiness = 10

10 is generally good for ‘I don’t want swapping to happen except if you *really* need it.

 

Systemd is the stupidest piece of stupid brain-dead init software ever invented.

A tale, in a log.
systemd: BOOTING !
systemd: Oh noes! /var needs fscking! let’s drop into emergency shell
systemd: Emergency shell! You should check out the log. It’ll totally tell you something pointless that’ll send you on a wild goose chase for half an hour.
systemd: Oh, by the way, I mounted /var cos I want to log there, and I won’t unmount it for you in emergency shell, cos that’s just helpful.
systemd: What, wait, you’re not going to use SysV are you? No, don’t touch tha<URK>
SysV: Booting.
SysV: Oh noes! /var needs fscking! Let’s try fscking it for you …
SysV: /var failed. needs manual intervention. Here’s an emergency shell. Not with /var mounted because I’m not a moron of a boot loader.
SysV: What’s that, you’ve fixed it? Oh, you can reboot with “shutdown -r now”, it’s fine, I won’t force you to use my own internal reboot command, because we’re all adults here.

*sigh*. Can I get those 2 hours of my life back please?

Varnish weird error

Are you getting a weird error from varnish that you’re having trouble working out? Is it cryptically saying that there’s an issue with your host definition in your VCL?

Expected ID got ';'
 (program line 165), at
 ('input' Line 20 Pos 30)
 .first_byte_timeout = 120;
 -----------------------------#

You need to add a time unit to your timeout definitions — ‘s’ for seconds, ‘m’ for minutes.¬† Stupid cryptic error is dumbly cryptic. Grrr.
https://varnish-cache.org/lists/pipermail/varnish-bugs/2011-August/003983.html

ARGH! A Rant about software developers

When software developers update their software to include new configuration options, they have a bunch of options to pick from, of how to handle installs running on the old options.

For example, you could

  1.  automatically update config
  2.  document a process to gracefully update config
  3.  Give human readable errors showing what changes you need to make to conifg
  4. ¬†Break the application with a super cryptic error message, and refuse to start until config is wiped with ‘new’ default config.

Why do developers keep picking 4? At least 2 horribly complex bits of software in the past year have decided to do that to me, which cost me a few days of head-bashing-against-desk trying to work out what was broken time. ūüôĀ