First G120 based design

This is the PCB design for my first G120 design. After checking it out to check for any errors, I’ll be firing this off to get the PCB’s made.

It’s a 5" LCD with capacitive touch and 800x480 display.

It’s part of a large 3 display clock I am working on. There will be 3 of these boards, albeit, only one with the WiFi interface.

The WiFi is for receiving sensor data from the home automation system so I can display temperature, humidity etc.

The boards communicate with each other using CAN bus. This is used, among other things, to syncronise the clocks and to change the display type etc.

I have designed a nice aluminium panel for it and the only part I am now trying to get made is the back box. I want to get this made in a hard wood. I have a local guy who makes beautiful teak furniture so trying to see if he can do this bit for me.

Appreciate any thoughts?


Nice. Your home automation system is going to be spoiled :slight_smile:

If you have any problems getting the local guy to help you out, I’d be interested in working with you on this.


Is the coin for a RTC?

What’s the board on the top right corner mounted perpendicular to the main board?

Why did you use CAN? I’ve never used it, so I’m curious about it.

Looks like it’s family from the one bellow :wink:

@ mhectorgato - If I had to guess, the vertical component is a switching power supply. Probably this one:

I use the horizontal version in my board designs :slight_smile:

Well spotted Igmoe. It is indeed the OKI regulator. I like these over the RECOM units as they are more than 50% cheaper. I have space for the vertical unit so I will go with that. They actually work out cheaper than discrete parts when build quantities are small as often you have to purchase 5 or 10 inductors when using the switching supplies. Not ideal for 1 off or small runs.

@ mhectorgato. The coin cell holder is for the RTC battery. With WiFi it will ideally use a time server to set the time but if none then the internal RTC will work well.

I am a big fan of CAN bus and I love the fact that it is multi-master. Makes for simple sensor interfacing as you don’t need to worry about coding the master to poll it. Just drop it on the bus and transmit the data with a unique ID and anyone on the bus can accept the data. You also don’t have to worry about checking for any current transmission as the bus controller takes care of this. There is a little bit of a learning curve but it is worth it if you want a reliable low payload communications network. A client and myself developed a CAN bus network for and ROV control system. Makes dropping in new modules easy as the whole lot works on a 4 wire connection (power and comms)

@ ianlee74. I would be very interested in this. I’ll need to redesign the box to work with your method of manufacture but that looks ideal. The whole box is going to be approx 400 x 100 x 50mm in size.

@ David@ Emrol. Interesting looking board. What does it do?

@ Dave - Which LCD panel did you go with?

The 5" one from Newhaven. I have the older version but I am buying 3 of the the newer ones to build the final system as they are higher brightness.

I still have the touch driver to write for it and that is on the cards once the boards come back.

I have tested the LCD part with a ChipworkX board and it works well.

Cool. Shoot me an email and we can discuss. ian at house of lees dot net.

@ Dave McLaughlin - Excellent project. What sort of range do you get with the CAN bus? In my system I’ve been contemplating using TCP/IP with POE, but it seems overkill for the level of communications needed.

I’ve done a commercial system running at 10Kbps on 1500m of ROV umbilical.

Distance is a function of the cable type and bus speed. I had a home automation system when I lived in Scotland that ran at 250Kbps with a maximum run of 200m from the farthest 2 points and no failures or bus errors.

@ andre.m I am not familiar with DaisyLink and only just had a quick glance at it now. From what I can see, DaisyLink requires a poll and request type system for all messages. CAN bus can also work in this manner but the normal way is for devices to transmit their data as and when they wish. There is no need for any master. Your only requirement is us the ID to determine the priority. Lower ID values are given priority over higher ID’s. The CAN controller takes care of the bus arbitration and any collisions. Similar in the way to Ethernet works, it is a CSMA type protocol which is non-destructive if there is a collision.

For instance, in my old home automation system I had a weather station that would transmit all the data at a preset interval. Any device on the network could listen for that data and act upon it. The boiler heating and control system would use this to work out if the heating had to come on to prevent freezing conditions, for instance. Other sensors in each room transmitted temperature, which again the heating system would act upon.

I am pretty sure that CAN bus would be considerably faster than DaisyLink but is limited to 8 bytes per payload and each would have it’s merits.

@ Dave - I currently work in the maritime field. Out of curiosity, which ROV system did you work on? (If you don’t mind me asking.)

Additional to the CAN bus stuff, the big advantage when there is a large number of messages on the bus is that you can have the controller filter only the ones you are interested in. It simply ignores them (but it does acknowledge then on the bus side and this is a major point. Any device on the bus who got an error will indicate this and the sending device will resend the message) and you only process the ones you are interested in.

@ Dave McLaughlin - Nice 3D preview !! I miss some decoupling capacitors near CPU/WIFI/SD module.

Well spotted on the caps Rob. They were added in last night but I have not updated the 3D image. :slight_smile:

I use Altium Designer and it does really nice 3D. I use it all the time to check clearances etc.

Just a quick 3D CAD model of an idea for the enclosure and front panel. The rear view is shown as a sectioned view so you can see the parts inside.

That’s going to be a top notch control panel, Dave. It almost sounds like you keep moving just so you can build a new home automation system :wink:

Thats some cool development.i’d be interested in how you automation system works? I’m doing some automatin myself but not using CAN

Hi Anthony,

I mainly run Homeseer with ZWave controllers. I also have a number of home made interfaces running Zigbee that I use to communicate using a USB receiver that talks Xap to Homeseer.

I have to use wireless as I live in an apartment with mainly solid walls so installing cables is not an option and certainly not WAF… :slight_smile:

Once this panel is completed, I will have it talking Xap over WiFi so that it can get updates from Homeseer and any devices I want to talk to it.

I am working on getting the plant watering system to talk to Homeseer so that I get the temperature and humidity from outside sensors as well as the current plant watering status. It will then send my wife a message if it detects that the plants are getting too dry. She doesn’t want to auto watering so this way she can decide when to water them :slight_smile:

The parts from GHI should be arriving this week and after I get back from holiday in 2 weeks time I will be building this system and should have the prototype going a little after this then it’s down to coding time :slight_smile:

What are you using at present yourself for home automation?

My home automation is not complete but using onboard relays, 1wire to do the automation. This project has been going for a while but making great progress and its evolving as time goes on…i might try CAN, look like an interesting interface.

You can view my progress here