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Robo-Tank 2.0 - Updated Controller
#1
Hi, I've just finished a hardware update for the controller, I've been selling this one for nearly a year and half now so figured it was time to make some changes based on feedback and what I've seen. 

Aside from the changes I was able to add extra filtering making the board less susceptible to noise and ripple from external DC equipment. Now when DC pumps or lights that draw an amp or more turn on the power doesn't drop momentarily and the +5v rail remains clean. I suspect this is what originally was causing the pH circuit to corrupt and cause a possible error on the DS18B20 sensor. Here's a video showing some measurements on the bench.



Physically the controller is the same size but ports have been changed, here's the list.
  • PCB is now 4 layers instead of 2. This provides a nice ground and power plan and helped reduce noise overall.
  • Controller can now be powered using a 24v DC power supply, this is nice if you want to plug 24v accessories in the DC ports.
  • Added a real time clock, RTC, so the controller isn't reliant on a network, with an RTC you can run it off line and overall makes a more reliable system as controller is in trouble if no time is available.
  • Replaced the USB connector for the sensor extension with an Ethernet RJ45 connector, this was done due to some USB cables don't work.
  • Added three 3.5mm phone connectors, these are connected to 6 PWM/Analog outputs, 2 per plug, and can be used for Kessil lights, Jabeo pumps and any other equipment that has this connector which is quite a bit, this makes it plug and play. The two 4pin plugs that are used today are still on the controller, these are just extensions.
  • Added 2nd 1-wire bus for DS18B20 temp sensors, this means temperature port 1 is isolated from temperature port 2 and 3, they now work independently 
  • Added extra jumper to the water sensor ports so they can be used for DS18B20 and DHT22 temp sensors as well. This means it'll be possible to run up to eight 1-wire buses for DS18B20's, no more needing to share a bus for multiple sensors, this will greatly improve DS18B20 reliability. 
  • Added 2 backup ports for 2 AC outlets, connect a float switch or regular switch to bypass the controller and control the AC outlet. These have the same function as the 3 backup ports for DC ports.
  • Removed one DC port due to no space on board, now there's a total of 6 + the feeder port.
  • Added speed control to Raspberry Pi cooling fan port, allows fan to be slowed down so it runs quieter.
  • Replaced the DIP switches for PWM/Analog ports to pluggable jumpers. Unfortunately this isn't an improvement, I prefer dip switches but it wasn't possible to use them due to size and automated mounting constraints. 
Here's some pictures of the prototype I have, on the 3rd and 4th picture you can see a location to plug in a DS3231 Real Time Clock, I've now decided to install a DS1307 on the board permanently, instead there will be a small CR1220 battery in that location to retain the clock when controller isn't powered up. Any battery will last over 5 years, some up to 10. With this it's possible to run the controller without a network connection and increases reliability.

A 20mm x 20mm cage fan will still fit in the same location and where the Pi plugs in there's no longer a bunch of header leads so I believe a low profile heat sink will fit on the Pi without an issue. I'm not 100% sure just yet as I don't have a heat sink but I'm going to make something the same size and verify but it looks like it'll be ok.

The extra expansion and extensions I have available will still work with this board however all the pin assignments for ports have changed for them and the controller.

Unfortunately I do need to raise the price $10-$15 due to 4 layer PCB and some extra components. Due to that I'm going to add a basic version of the controller, it'll probably be around $75 assembled. I expect to have these available in about a month.

If anyone has any questions or suggestions let me know.

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Messages In This Thread
Robo-Tank 2.0 - Updated Controller - by Rob F - 09-06-2021, 01:30 PM
RE: Robo-Tank 2.0 - Updated Controller - by Rob F - 09-06-2021, 10:28 PM
RE: Robo-Tank 2.0 - Updated Controller - by pwest - 09-12-2021, 12:00 PM
RE: Robo-Tank 2.0 - Updated Controller - by Rob F - 09-12-2021, 12:32 PM
RE: Robo-Tank 2.0 - Updated Controller - by Rob F - 09-17-2021, 02:02 PM
RE: Robo-Tank 2.0 - Updated Controller - by Rob F - 09-24-2021, 09:00 AM
RE: Robo-Tank 2.0 - Updated Controller - by Rob F - 09-24-2021, 10:26 PM
RE: Robo-Tank 2.0 - Updated Controller - by Dom59 - 10-20-2021, 11:43 AM
RE: Robo-Tank 2.0 - Updated Controller - by Rob F - 10-20-2021, 02:17 PM
RE: Robo-Tank 2.0 - Updated Controller - by Dom59 - 10-21-2021, 09:38 AM
RE: Robo-Tank 2.0 - Updated Controller - by Rob F - 10-21-2021, 06:10 PM
RE: Robo-Tank 2.0 - Updated Controller - by Rob F - 10-25-2021, 12:27 AM
RE: Robo-Tank 2.0 - Updated Controller - by Rob F - 10-26-2021, 05:40 PM

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