TED $20 Ebay

Xringer · 12-17-13, 11:55 PM

I saw her post. It was about a receiver, not how the transmitter timing works..

But, I just looked the comments below her post, and found the Transmitter IC part number. (actually a transceiver).
It's the Home automation modem TDA5051A. It uses crystal clock in the 7mhz range for controlling the data I/O lines, (like any old tech modem).
And I assume it's micro controller is running TED firmware (which has a RTC running) is selecting the start packet time, once a second.

Without some knowledge of the micro controller, I'm pretty much where I started.

So, I'm going to assume the start time will be random, and not linked into the 60hz grid (which is a pretty good timebase).
And I'll assume the micro controller's clock is going to drift, in both transmitters (MTUs).

So, there will be clock frequency drift and that will cause signal interference.
I'm somewhat sure, because the time-of-day-clock on the LCD display has a long term error. (it's not using the 60hz grid for time keeping).

If they drift so the transmitters are interfering, that could cause the lost of hours of data..
So, I think circuit isolation will be needed.. Yikes it's almost 1AM..

~~~~

I wonder if they put a Listen-before-Transmit routine in the firmware??

12-17-13, 11:55 PM	#16
Xringer Lex Parsimoniae Join Date: Feb 2009 Location: Woburn, MA Posts: 4,918 Thanks: 114 Thanked 250 Times in 230 Posts	I saw her post. It was about a receiver, not how the transmitter timing works.. But, I just looked the comments below her post, and found the Transmitter IC part number. (actually a transceiver). It's the Home automation modem TDA5051A. It uses crystal clock in the 7mhz range for controlling the data I/O lines, (like any old tech modem). And I assume it's micro controller is running TED firmware (which has a RTC running) is selecting the start packet time, once a second. Without some knowledge of the micro controller, I'm pretty much where I started. So, I'm going to assume the start time will be random, and not linked into the 60hz grid (which is a pretty good timebase). And I'll assume the micro controller's clock is going to drift, in both transmitters (MTUs). So, there will be clock frequency drift and that will cause signal interference. I'm somewhat sure, because the time-of-day-clock on the LCD display has a long term error. (it's not using the 60hz grid for time keeping). If they drift so the transmitters are interfering, that could cause the lost of hours of data.. So, I think circuit isolation will be needed.. Yikes it's almost 1AM.. ~~~~ I wonder if they put a Listen-before-Transmit routine in the firmware?? __________________ My hobby is installing & trying to repair mini-splits EPA 608 Type 1 Technician Certification ~ 5 lbs or less..