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Forum Index : Microcontroller and PC projects : All of Geoff’s projects on one PCB...
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Grogster Admin Group  Joined: 31/12/2012 Location: New ZealandPosts: 9077 |
This is a shot of my latest PCB I just finished assembling and testing at the weekend: 
It incorporates a full colour maximite as the CPU("BRAIN" on silkscreen), a 150 Micromite as an I2C port extender to give me an extra two serial ports("SUBSYS" on silkscreen), and a VT100 to run a switchable static VGA screen when remote-access is enabled("STATIC VGA" on silkscreen). Network access via console on COM1. When network is enabled by the Maximite, all the relays at the top of the board switch on do do various things. They switch the COM1 from the maximite through to the network module, isolate the keyboard to prevent local tampering when in remote mode, and switch the VGA from the maximite, to the VT100. The switching is done via a latching relay, so that you can still enter the maximite editor via the network, and it won't cause the network to drop off, which it was doing in the original concept when I had a standard relay(it would drop out when the editor was called, which would kill the network link to the maximite!). Restarting the system pulses the latching relay into the "Normal" mode by default. The lower relay is a mains-fail detect circuit, which is powered directly from the 12v AC side of the mains transformer, so that if the mains fails, the AC vanishes, and the relay drops out, which the Maximite is designed to pick up on. The external PSU has full battery backup to keep the system running if the mains fails. As the network module is also powered ONLY when remote access is requested, the chances of any kind of port-scanner finding the system and letting hackers in, is extremely unlikely. Not to say that this could not ever happen, but keeping the network module powered down when not being used prevents it talking to the network in any way, which makes it pretty secure, and so long as you don't make it known which port the module is on, only a port-scanner should be able to find the system, and only while in remote access mode - not THAT likely. It also saves on power consumption too, as the network module is quite thirsty at about 250mA... This board is the prototype, and has both the dot-matrix and thermal printer interfaces, but I have been so happy with the results of the thermal printer testing, that the final version of the board will not have the dot-matrix interface on it. Final version of board also has changes around the 338 regulator - extra caps and diodes etc, which are not on this one. ...and the final will use a genuine 338!  (see my other thread about killing regulators in the electronics forum). Smoke makes things work. When the smoke gets out, it stops! |
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| WhiteWizzard Guru  Joined: 05/04/2013 Location: United KingdomPosts: 2794 |
Thats pretty cool Grogs! Out of interest, what size PCB is that? Did you get made in China; and if so, then how much did they charge for what quantity (if you don't mind me asking!)? Double sided I assume?  For everything Micromite visit micromite.org Direct Email: whitewizzard@micromite.o |
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Zonker Guru Joined: 18/08/2012 Location: United StatesPosts: 761 |
Wow.. Nice Layout big G..! |
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| paceman Guru Joined: 07/10/2011 Location: AustraliaPosts: 1329 |
I'm astounded Grogs but what are you going to use it for? |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9077 |
@ WW - 300mm x 150mm. Batch of five boards(you cannot get less) - about US$70 I think, from memory. Yes, double-sided. Got them from Shenzhen2U. @ paceman - It's the new "Motherboard" for my security system. At the moment, I have the main system running on PICAXE with ALfat for filesystem. The annoying bit about this approach, is that you have to take the SD card out and put it in a laptop to edit the database files. The Maximite allows this to happen all on the one board, without having to remove the SD card or use a laptop to change the database files. Technically, I could get the ALfat to edit the files, but the PICAXE has a limited amount of memory for these kinds of tasks when combined with the rest of the system, whereas the Maximite has plenty of memory for that. The message logging etc for the current setup is all done on another separate laptop with TeraTerm and a pager receiver. The idea behind the new board, is to centralize EVERYTHING onto one board, and the Maximite does all the work, can edit the database entries and logs all activity to the SD card - as well as printing it out on the thermal printer as each message comes up. Smoke makes things work. When the smoke gets out, it stops! |
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Geoffg Guru Joined: 06/06/2011 Location: AustraliaPosts: 3165 |
Impressive. In fact fantastic - what a board! Obviously a lot of experience has gone into this. I like how it appears to have stereo audio and the the Maximite CPU is labelled BRAIN! That board is very cool. Geoff Graham - http://geoffg.net |
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| WhiteWizzard Guru Joined: 05/04/2013 Location: United KingdomPosts: 2794 |
Grogs, When you say "security system", can you elaborate a bit more For everything Micromite visit micromite.org Direct Email: whitewizzard@micromite.o |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9077 |
@ Geoff - Thank you for you nice words.  But, without all three of your projects(Colour Maximite, MicroMite and VT100), this board would not be.
However, I did have fun connecting all three of them on the same board and system, and they work very well togeather - you could say it is "Harmony".....  
...sorry - bad joke... @ WW - It's a wireless door/window system thing. All windows and doors(or anything else you want to monitor) have wireless transmitter nodes on them. Each node is individually addressable in the database, and a separate text message can be assigned to each of those node transmitters. They use the Radiometrix series of modules(despite their cost) for a couple of reasons: (1) Radiometrix modules are type-approved(lab tested) for use in the country they are sold into so I know they are compliant as a transmitter device, and (2) They work all the time, every time. I have several hundred transmitter nodes in place at several different sites, and none of the transmitters have ever failed - yet! That's 24/7 for about 5 years so far. Original nodes used PICAXE, but new nodes use the 170 MicroMite. Flick me a PM or email me(I know you have the address), and I could send you some more details if you like. The current system still uses POCSAG pagers and a pager transmitter, but I am already working on porting to cell-phones and txt messages(SMS), as the cell-phone technology now, is so much more reliable then it was before - can you remember the last time you could NOT send a txt message?(rhetorical) To say nothing of the fact that pagers are still about $250 each vs a basic cell-phone for less then $20 - I have seen some on special from time to time for about $10!
Smoke makes things work. When the smoke gets out, it stops! |
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| viscomjim Guru Joined: 08/01/2014 Location: United StatesPosts: 925 |
Grogster, very very cool undertaking and result!!!! The only thing you forgot is the MP3 module connected to a 300 watt amp so it can scream at the intruders to get the hell out and then the sound of a 12 gauge shot gun being cocked... |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9077 |
...I'm sure that could be added with remote activation of the amp! Smoke makes things work. When the smoke gets out, it stops! |
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| viscomjim Guru Joined: 08/01/2014 Location: United StatesPosts: 925 |
Grogster, what network module are you using there? |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9077 |
It's a WizNet 107SR module with RS232 interface. You can also get it in TTL. I chose the 232 for this job, as then it could sit in between the normal 232 "COM1" D-9 socket on the PCB(which goes off to the pager transmitter as RS232), which then lets me use this module as a 232 back to COM1 on the Maximite. There is a keyswitch on the front panel, and when turned, this puts the system into remote admin mode, and opens the cosole on COM1. If you just want to play with the module in a standard arrangement to a Micromite etc, then you need the TTL version. Smoke makes things work. When the smoke gets out, it stops! |
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| WhiteWizzard Guru Joined: 05/04/2013 Location: United KingdomPosts: 2794 |
Would be fantastic if you can email me more info - thanks. Fully agree with you about the RadioMetrix modules - they are my number one choice too. Their factory is in Mauritius and I was hoping to go see them when we got married but thought it best not upset the wife with more work stuff on 'honeymoon'! Thanks in advance . . . . For everything Micromite visit micromite.org Direct Email: whitewizzard@micromite.o |
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| Grogster Admin Group Joined: 31/12/2012 Location: New ZealandPosts: 9077 |
Yes, the wife would not appreciate that idea. I will email you. Smoke makes things work. When the smoke gets out, it stops! |
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