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Author Topic: CM15 with RS232 interface  (Read 10010 times)

LinTronic

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CM15 with RS232 interface
« on: September 07, 2011, 10:36:04 AM »

CM15 with USB is already available - but we are not able to use it with our "LinTronic TT455-RT-238" as it holds no USB connector but standard RS232.

I wonder why the CM15 was not designed with RS232 - as it would be very to access it with a USB/RS232 cable.

We need CM15 with RS232 interface - any plans ?

Rgds,
Michael Lindgaard http://lintronic.dk
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dhouston

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Re: CM15 with RS232 interface
« Reply #1 on: September 07, 2011, 12:28:02 PM »

In the USA, the CM15A replaced the CM11A (in Europe C12, IIRC) which was RS232. I imagine they thought USB was better as native RS232 ports were disappearing from PCs at about that time. IOW, it's highly unlikely X-10 plans an RS232 version.

There are a couple of solutions.

1. You can add USB host functions to your device using FTDI's Viniculum chip.

2. You can design a daughterboard replacement for the Cypress MCU used in the CM15. I've actually designed two such daughterboards, one with a PIC and one with a ZBasic (AVR) chip. Both had bootloaders so field updates were possible. But I never released them because desoldering the Cypress MCU is not an easy task, even for those experienced with a soldering iron and because it was just too ambitious a project given my age and poor health. (I still plan a daughterboard for the RR501, which I call RR5x5, that adds isolated RS232, isolated 50-ohm BNC antenna connector, and an isolated output port for sending IR/RF with external hardware.)

The first option is the best one for you as it involves no DIY modifications of the CM15 and will work worldwide.

Should you wish to explore the second option, ZBasic worked with me and has included low level X-10 functions in their compiler. They are available in most of their chips although the ZX-32n is probably the most suitable here. The X-10 functions operate in the background more or less like UARTs sending/receiving as needed at ZC. All the user need do is define the pins (some restrictions for ZC) and define the bit arrays for TX & RX. Flags signal various conditions. Optional signals that emulate those in the CM15 are included. You can also control whether signals are active high or active low so you can emulate a TW523/XM10 and interface to legacy controllers.
See my page on the CM15A for oscilloscope screenshots of the various signals...
« Last Edit: September 07, 2011, 01:58:25 PM by dhouston »
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Brian H

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Re: CM15 with RS232 interface
« Reply #2 on: September 07, 2011, 01:51:54 PM »

The closest interface I have seen was the CM14A that was serial but I never saw any being sold. I believe some members here may have tested the beta units.
I did find schematics of it on the FCC Web Site.
Schematic title "IBM JR Computer Interface".
« Last Edit: September 07, 2011, 02:02:24 PM by Brian H »
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dhouston

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Re: CM15 with RS232 interface
« Reply #3 on: September 16, 2011, 07:26:01 AM »

Maxim's MAX3421E IC is simpler (USB Host/Peripheral/DI/DO) and less expensive than the FTDI Viniculum (host/slave, MCU, etc.) I mentioned earlier. Maxim has an AppNote (AN3785) explaining it.
Neil Cherry's Linux Home Automation site has information on the CM15A protocol. I don't know how up-to-date it may be. Neil wrote a Linux driver for the CM15A, the CM19A, and more.
Mochad works with the CM15A so you can probably gleen info on the protocol from its source. It also works with OpenRemote.
Jan Axelson's website is always a great source for USB info.
AFAIK, X-10 has never released documentation on the CM15A communications protocol. It would be a great help to have that.
« Last Edit: September 18, 2011, 08:25:42 AM by dhouston »
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dave w

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Re: CM15 with RS232 interface
« Reply #4 on: September 16, 2011, 09:27:30 AM »

null
« Last Edit: September 18, 2011, 11:38:39 AM by dave w »
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dhouston

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Re: CM15 with RS232 interface
« Reply #5 on: September 18, 2011, 11:08:06 AM »

CM15 with USB is already available - but we are not able to use it with our "LinTronic TT455-RT-238" as it holds no USB connector but standard RS232.

Michael,

After a bit of research, I think it would be feasible to create a Serial<->USB_Host adapter using a chip with an SPI interface like the MAX3421E and a small PIC or AVR. The µController would need to support SPI in hardware - even recent 8-pin PICs with hardware USARTs (e.g. PIC12F1822) might be adequate - I think even their internal oscillators are accurate enough. It would be much simpler if X-10 would publish the CM15A communications protocol but I think enough can be gleaned to make it work. Whether it could also be used with other devices would, I suspect, depend on knowing the device(s) communications protocol(s).

Another approach would be to use newer PIC or AVR chips that have USB built-in and can play host or peripheral. That's a bit more difficult, IMO.
« Last Edit: September 18, 2011, 01:47:27 PM by dhouston »
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