Digital Timer Wish List

[Noggin]

I have a couple of Intermatic mechanical timers for my pumps and I'm constantly annoyed by them. At least once a week I'm outiside manually controlling them to get the cleaner running a while or to get some water flowing to get additional chemicals mixed into the water. The manual control always revolves around making sure the booster doesn't run when the main pump is running, either by adjusting the position of both dials (so the time is never right) or by moving the on/off switches.

Also, last week I was poking around on one of the timers and shorted a +120v to the on/off switch and it welded itself to the on position. I used a wrench to break it loose and it appears to be working, but it may be running a bit slower than it should be. The time doesn't seem to be right on the dial after a couple of days now. Last night, my second timer got stuck when it reached the "off" switch (think I've seen it called a dog?) and my booster pump ran all night mostly without the main pump. So, not only do I get annoyed by having to adjust things on the timers every few days, but I also am losing faith that they're working properly.

I'm an electrical engineer and have the ability to design my own digital timer with as much functionality as I'd like it to have. If you were looking to buy a digital timer, what kind of features would you want it to have? This is what I've thought of so far:

• Temperature sensor - If the temperature drops below 0 deg C for more than an hour, run the pumps. If the temperature drops below -10 deg C, immediately run the pumps[/*:m:2zmcmjwp]
• Allow a pump to be a slave to a master, the slave can only run if the master is running[/*:m:2zmcmjwp]
• Have an "Add 15 minutes run time" button to the pumps so if I do want to run the cleaner, I can just press it 4 times to run it for an hour. If the cleaner pump is set as a slave to any other pump, then its master pump would also run for the same amount of time[/*:m:2zmcmjwp]
• Current monitoring - If current drops to 0 unexpectedly, then it might indicate a problem. If current is higher than normal, it might indicate a problem[/*:m:2zmcmjwp]
• Current logging - log current draw to an SD card periodically[/*:m:2zmcmjwp]
• WiFi - If it is close enough to your house, you could connect directly to the timer via a laptop or PC to set the schedule and download the current log. You could also view the status of the device while it is running[/*:m:2zmcmjwp]
• Bama Rambler: Real time clock to keep the time in the event of a power loss[/*:m:2zmcmjwp]
• Leebo: Android/iPhone app[/*:m:2zmcmjwp]

Anyone else have any ideas to add to the list?

 

[Bama Rambler]

Looks like you covered about everything. That's sounding like a small PLC and a tiny operator interface. You could probably do all that with a home automation system. And it would even keep the time set!

 

[Noggin]

And it would even keep the time set!

Real time clock! Thought of that last night but forgot to add it to my list.

 

[Leebo]

Don't forget an iphone app to control anything while you're on vacation or at work. Also allow it to send you a notification if it runs into any issues.

 

[Noggin]

Added... I have been wanting an excuse to build an Android app. I've worked on an iPhone app a year or so ago, but I don't have a Mac easily accessible to develop for an iPhone. I'm not sure that the WiFi from my home network will reach out to the pump timers, but if it does it would be nearly trivial to send emails. An Android app would be a fairly decent thing to add eventually.

 

[Bama Rambler]

Before you reinvent the wheel, take a look at some of the home automation systems (Insteon, UPB, Z-wave, etc.). They can do most everything you want plus the android & apple apps and the wifi and email support. You may be better putting together a system of those parts.

 

[Noggin]

Reinventing the wheel is the fun part!

 

[Bama Rambler]

Reinventing the wheel is the fun part!

I've been known to do that a time or two even when the wheel is sitting right beside me! :-D

 

[Noggin]

Well, the boring part is done... now comes the expensive part. Ordering all of the parts.

 

[Noggin]

Hardware is almost complete. I just need to order the op-amps for the current transformers and an analog reference. I suppose I should get a battery for the clock too, else it'll be fairly worthless.

 

[Isaac-1]

Looks good, are those CT's at L1 and L2? if so what are their function?

 

[karmabiker]

That is very very cool.

 

[Noggin]

Looks good, are those CT's at L1 and L2? if so what are their function?

I'm assuming that by CT you mean Current Transformer; and yes, they are current transformers. You can see a rather large hole above and below each of the transformers. I need to add a jumper from one of the holes, through the transformer, and into the other hole. The secondary coil of the transformer will output a small amount of current proportional to the current through the wire (which goes through a pump). I can measure this current and determine the pump current. I'm hoping that the pump current will change enough as the filter and/or the pump basket gets clogged. If it does, then I'll be able to either cut off the pumps or send a message to my phone.

 

[CraigMW]

Looks pretty slick. What microcontroller/platform is this based on? I had originally considered "rolling my own" automation controller using an Arduino, but couldn't justify the time to do it. It would have been fun, but just too much work, especially to add a web based interface. Now that the Raspberry Pi is out there, it probably would not have been as difficult. Alas, to many other priorities at the head of the line.

So it looks like you have a WiFi daughter board (shield?), so you must be adding some web-based interface, which basically pushes this into the territory of much more expensive automation systems. Why no relay(s) for lighting or other features (or is that what the L1 and L2 terminals on the right side of the terminal block for)?

 

[Noggin]

The board design is based on a 32-bit PIC processor, PIC32MX695F512L. I'll be running the TCP/IP stack on the chip as well as a USB stack. L1 and L2 are just line 1 and line 2, the two AC phases for input power. The two orange devices are relays for powering the two pumps. I don't have any other powered equipment out there so no need for additional controls. The wifi daughter board is kind of an annoying situation. The WiFi module on the board is really what I wanted, but it is only available on the daughter board right now. It won't be for sale by itself for another couple of months. I could have gotten an 802.11 b module, but the 802.11 b/g is what is recommended for most situations unless you have a requirement for low power. I'm not even sure if the WiFi will reach my house though, so it might be a blessing that it is a pluggable module as it'll let me remove it and use it for something else.

Have you looked at the BeagleBone Black? I think I'd take one of those over a Raspberry Pi, though it is considerably more expensive. It was just recently released though, so I don't know how the BSPs look for it. I'd REALLY like to learn programming for Android / Linux and I was planning on getting a BeagleBone Black and the touchscreen cape for it (a "cape" is basically "shield" but for a BeagleBone).

 

[RMoss]

Are you planning to sell these? Because I need one!

 

[CraigMW]

The board design is based on a 32-bit PIC processor, PIC32MX695F512L. I'll be running the TCP/IP stack on the chip as well as a USB stack. L1 and L2 are just line 1 and line 2, the two AC phases for input power. The two orange devices are relays for powering the two pumps. I don't have any other powered equipment out there so no need for additional controls. The wifi daughter board is kind of an annoying situation. The WiFi module on the board is really what I wanted, but it is only available on the daughter board right now. It won't be for sale by itself for another couple of months. I could have gotten an 802.11 b module, but the 802.11 b/g is what is recommended for most situations unless you have a requirement for low power. I'm not even sure if the WiFi will reach my house though, so it might be a blessing that it is a pluggable module as it'll let me remove it and use it for something else.

Have you looked at the BeagleBone Black? I think I'd take one of those over a Raspberry Pi, though it is considerably more expensive. It was just recently released though, so I don't know how the BSPs look for it. I'd REALLY like to learn programming for Android / Linux and I was planning on getting a BeagleBone Black and the touchscreen cape for it (a "cape" is basically "shield" but for a BeagleBone).

I just started reading about the BeagleBone, and it does seem to have features of the Arduino and RPi in one board. It is new, so not much out there yet. There are some reasonable ways to interface from an RPi using 1-Wire stuff (e.g. digital switches, ADCs, temperature sensors, etc). There are also folks interfacing Arduinos with an RPi using SPI. The advantage of the Arduino is that it is quite mature and there are plenty of libraries and code examples, but it is quite limited for web-based apps (or anything memory intensive for that matter).

 

[Noggin]

Are you planning to sell these? Because I need one!

Maybe. I'd need to investigate the legal issues involved with selling them first because of them being AC powered. I also suspect that the price I'd have to sell it at would deter anyone else from buying it. I've got about $500 into just getting one unit up and running. I think it costs about $250 in parts alone. If I could sell it for $250, that wouldn't be that bad considering I've seen a single mechanical timer going for $100, but I can't sell it for that low.

Maybe though. I work for an engineering firm and if I get this thing working the way I want it to work, the boss-man might sell it for me and pay me royalties or something. If that happened, we could probably get the cost down.

 

[Noggin]

I just started reading about the BeagleBone, and it does seem to have features of the Arduino and RPi in one board. It is new, so not much out there yet. There are some reasonable ways to interface from an RPi using 1-Wire stuff (e.g. digital switches, ADCs, temperature sensors, etc). There are also folks interfacing Arduinos with an RPi using SPI. The advantage of the Arduino is that it is quite mature and there are plenty of libraries and code examples, but it is quite limited for web-based apps (or anything memory intensive for that matter).

I haven't looked at the Arduino very much, but I have been impressed with the library that has been developed for it and some of the projects people have done with it.

 

[Brewer]

Wow! I was very impressed with your board layout, but couldn't tell if your first jpg was a prototyping board or a production quality pcb, with surface-mount capability. Your board even has all the production quality part-reference silk-screening. I too have often fought the urge to "re-invent the wheel". I checked out the specs of the PIC32MXXXX line of Microcontrollers, and they are certainly a far cry from the 30-year-old Micro-Cs my in-house automation gear is built around. Microchip's web-site indicated the availability of PC compatrable development boards, but I am curious --- Can the PIC32 be programmed directly from, the PC (with suitable development software), via the USB port?