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Can Medusa Mini handle this?


#1

I want to build a nice room temperature control using
[ul]USB Ser SP (Sock Prog) https://www.ghielectronics.com/catalog/product/437
RS485 Module (Sock U) https://www.ghielectronics.com/catalog/product/479
N18 DIsplay (Sock S) https://www.ghielectronics.com/catalog/product/425
Temp&Humidity (Sock X) https://www.ghielectronics.com/catalog/product/344[/ul]

But I need 3 additional push buttons, which I would have connected to any available X or Y socket.
But all sockets are used already.
Can anyone tell me if these modules would leave 3 GPIO’s free, so I could squeeze my buttons in between by breakout boards?

At least my Prototype would be built from std Gadgeteer modules. Hope they fit in a standard German socket ‘box’. (Except USB Module, This I would replace with power only when mounted to wall.)
For the outer part I would use my old Temperature controller housings from Bush Jäger (The display + 3 buttons should just fit in :slight_smile:

The valves would be controlled by a standard RS485 capable Dig Out Module with built in relais for 230V (like ICP CON I-70 61 http://www.icpdas.com/products/Remote_IO/i-7000/i-7061d.htm)


#2

S socket has 3 unused pins. You will have to poll most likely to check for button presses.


#3

@ Architect - Looks like N18 Display is using them for Backlight, reset, …Specially Backlight is a feature I would need.

But looking at the schematics shows me that the X Socket would have some spare AD’s if only Temp&Humidity is connected, which uses only pin 3 and 4.
Thank you anyway.

Thinking more in detail it would make sense anyways to have 3 types of devices:

  1. Display + Buttons + T&H (UI+T&H)
  2. Display + Buttons (UI only)
  3. T&H (T&H only)
    This would reduce costs a bit. In final configuration I have 11 separate regulation circles, but some of them are close together, so I can control them from a singe UI module.

btw. Is it possible to store persistent user data on a Medusa Mini (only a couple of bytes) without an extra module?


#4

You can use the Arduino EEPROM library to store a few bytes on the board, even when powered off. We have not tested it though.

http://arduino.cc/en/Reference/EEPROM

Another thing to keep in mind is that the RS485 is not confirmed to work yet. It has a driver but it has not been tested.

https://www.ghielectronics.com/docs/189/gadgeteering-module-support


#5

@ Reinhard Ostermeier - Yes, you are right. I should’ve checked the schematics.


#6

@ John - If arduino and Gadgeteer Driver are open source, I think I’m able to get it work.


#7

Does anyone know a nice Relay out module I can control via RS485?
The one that I hade in mind (http://www.icpdas.com/products/Remote_IO/i-7000/i-7061d.htm) costs over 100€.
I need about 8 independent relays (normaly open) for 230V 1Amps.
The protocol does not rally matter (DCON, Modbus RTU, …)

I’ve been think about using the Rel16 module + MedusaMini + RS485, but that’s also not really cheap, and if the pins are open on the bottom of the relays board (as I assume) I have to take care of that too (250V).
Also 16 Relays are too much. There was a 4 Relay module. But I can’t find it in the catalog anymore.


#8

I believe the 4 relay module was produced by Seeed, but I do not believe it is still available even through them.


#9

Time to do a DIY relay module just for your needs I’d say…


#10

@ Brett - unfortunately I’m more the software guy. And it’s one thing to connect some wires and relays that will switch 230V, but designing a circuit board that will run unattended in my house :think:


#11

I agree, a DIY mains relay is not for the faint at heart. I personally would be cautious about doing this, but honestly you really don’t get many alternatives, particularly if you’re wanting to have a specific number of relays. I did buy a “powertail” device in case I wanted to switch a single device (haven’t yet used it though) but even this only goes a small way to removing the risk.


#12

I need 7 or 8 relays at one place and 5 at a second place.
So I thought a 8 Relay module would be perfect.
But I don’t want anything that has open pins or a open circuit board.
RS485 is because I need a bus system that can go through the whole house.
Wireless would be an option, but since I can easily put new/additional wires from on spot to another, a wired bus makes more sense.
Ethernet is usually more expensive as RS485, and I have often used RS485 at work already.


#13

If I read the schematics correct it does not matter by which socket I apply the 3.3 and 5V to Medusa Mini.
So I could supply it lets they through the U Socket and only connect a cable to PROG Socket when I want to do a update.
But what happens when the Board already has Power and I additionally connect a USB-Client SP, which also applies power?
I would assume that nothing happens, and the needed power is drained half/half from both sources.
Any one who thinks different?


#14

Can anyone answer my question from my last post, about applying 2 power sources providing 3v3 and 5v0?
I don’t want to kill my Medusa when I finally get it.
I tried to read the USB DP module schematics, but I’m not sure what all the components are for.


#15

It is not recommended to use two power sources on the same board. However, based on the senario that you came up with, you could keep the power USB to SP module left in the PROG socket and use the non powered USB to Serial in the U socket.


#16

@ Aron - It’s a bit different.
I do not have enough space to let the USB SP connected.
For programming I would open the housing and connect the USB SP to the unused PROG socket.
After update I would remove it and the module is powered by the U socket where a RS485 module is connected (and the power is injected by something in the middle).
So for programming / debugging I would have 2 power sources.

Optionally I can power it via PROG socket, and for updating I disconnect external power source and connect USB SP module.
Might be easier anyway then ripping of the cable to RS485.