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12 analog-channel-telemetry pairs with AVR

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fjpompeo

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12 analog channel telemetry pair with AVR

I need an 12 channel telemetry mux(TX side) and demux(RX receiver) project to monitor 4 temperature, 4 current and 4 voltage analog channels. I really would like to use AD converter on TX side and DA converter on RX side. As an example if I have 100mV on channel one (TX side) the same voltage will be present in the channel one (RX side). As a matter of fact the link may be made using a pair of wires simulating a RF transmitter just for evaluation purposes.

I really appreciate to use AVR micro controllers.

Thanks in advance,

Fernando.
 

Re: 12 analog channel telemetry pair with AVR

Hi,

Please ask a detailed question.

Klaus
 

Re: 12 analog channel telemetry pair with AVR

Dear KlausST,

Hello KlausST,
I need to monitor the voltage of the battery, current consumed during transmission and heatsink temperature of four radios during a VHF / UHF contest that will take place in July in the winter here where I live.I was thinking of using two microcontrollers for this task connected together by a cable with standard RS485 interface. The distance is small, about 200m between the hut and the top of the antennas. At the receiver outputs, the ICL7107 ICs will be connected in millivolts range.

I hope I have been clearer in this description of what I need.

Thanks in advance,

Fernando - PU2PLL
 

Re: 12 analog channel telemetry pair with AVR

Hi,

While I´m still confused about your setup ... mainly I wonder how and where the ICL7101 are used.
A draft could clarify things.

Data transfer with RS485 over 200m - assuming you use the correct cables with terminaton - should be no problem.

Sttill no clear question. Still not clear what the problem is.

Klaus
 

Re: 12 analog channel telemetry pair with AVR

He said to use DAC at the receiver. Apparently received signal should be output as 12 analog channels and displayed on 7107 3.5 digit analog modules. Feasible, but not particularly reasonable, I think. Is there a serious reason to convert the signal back to analog, besides using analog display modules?

Why not making the receiver side fully digital?
 

Re: 12 analog channel telemetry pair with AVR

Hi,

like this:

4 x (Voltage, Current, Temperature) --> 12 CH ADC --> microcontroller/UART --> TTL/RS485 --> 200m cable --> RS485/TTL --> UART/microcontroller --> 12 CH DAC --> 12 x ICL7107 --> 12 x display


I agre with FvM to use such a solution:
4 x (Voltage, Current, Temperature) --> 12 CH ADC --> microcontroller/UART --> TTL/RS485 --> 200m cable --> RS485/TTL --> UART/microcontroller --> dig controlled display

Now it depends on your display requirements:
Mechanical size, mechanical position, interface...
Theoretically you could display all 12 values on a singe 4 x 20 character LCDisplay.

If it´s just for temporary use:
Then I recommend a PC (or raspberry or similar) at the receiver side. Display the values on a usual PC monitor --> Less development effort.

Klaus


Added:
What display refresh rate do you want?
For 3 digit displays the best-fit is a 10 bit ADC.
 

Re: 12 analog channel telemetry pair with AVR

KlausST said:
Hi,

like this:

4 x (Voltage, Current, Temperature) --> 12 CH ADC --> microcontroller/UART --> TTL/RS485 --> 200m cable --> RS485/TTL --> UART/microcontroller --> 12 CH DAC --> 12 x ICL7107 --> 12 x display


I agre with FvM to use such a solution:
4 x (Voltage, Current, Temperature) --> 12 CH ADC --> microcontroller/UART --> TTL/RS485 --> 200m cable --> RS485/TTL --> UART/microcontroller --> dig controlled display

Now it depends on your display requirements:
Mechanical size, mechanical position, interface...
Theoretically you could display all 12 values on a singe 4 x 20 character LCDisplay.

If it´s just for temporary use:
Then I recommend a PC (or raspberry or similar) at the receiver side. Display the values on a usual PC monitor --> Less development effort.

Klaus


Added:
What display refresh rate do you want?
For 3 digit displays the best-fit is a 10 bit ADC.
Click to expand...


Sorry the delay in reply forgot my password!!

Display can be 3 digits like 13,8V and 18,5A and 30,6ºC for each channel is more then enough and if possible in a four line x 20 characters
or four line x 40 characters so in the second option I can inform the ID of the repeater too.

Regards,
Fernando
 

Re: 12 analog channel telemetry pair with AVR

Fernando, the reason for querying your project is it is inefficient the way to propose to do it.
You need an MCU (AVR or some other type) at both ends, one to select which analog channel you are reading and digitize the voltage, the other to drive the display. Instead of reading and replicating the voltage at the far end, why not just send the voltage information straight to the display.

You propose:
12 way MUX -> ADC -> MCU -> UART -> ------ cable ----- -> UART -> MCU -> DAC -> ICL7107 -> display
why not do it this way:
12 way MUX -> ADC -> MCU -> UART -> ------ cable ----- -> UART -> MCU -> display

which is simpler, cheaper and more accurate.

Brian.
 

Re: 12 analog channel telemetry pair with AVR

betwixt said:
why not do it this way:
12 way MUX -> ADC -> MCU -> UART -> ------ cable ----- -> UART -> MCU -> display
Click to expand...

Some AVR microcontrollers have 16 ADC channels, so even the external analog MUX device could be eliminated from this scheme.
 

Re: 12 analog channel telemetry pair with AVR

I think they want something like this, it's a control box sitting on my desk beside me. It shows time and date then some temperatures and the bottom line shows the state of three water pumps.
20180524_120003a.jpg
All the data is sent remotely by cable or wireless but the numbers are calculated and displayed without digital to analog conversion.

Brian.
 

Re: 12 analog channel telemetry pair with AVR

betwixt said:
I think they want something like this, it's a control box sitting on my desk beside me. It shows time and date then some temperatures and the bottom line shows the state of three water pumps.
View attachment 146849
All the data is sent remotely by cable or wireless but the numbers are calculated and displayed without digital to analog conversion.

Brian.
Click to expand...

Hi folks, very thank you for all tips. Well I need to monitor voltage, temperature and current of the radios installed more or less 200m far from my tent. It doesn't matter if the information is in analog or digital, with or without mux since I have all this info in a 4 line x 80 characters LCD display with an easy way to check so I will be very busy taking care of my notebook and having a lot of notes during the contests. I'm sure you can help me with this equipo.

Regards,

Fernando - Call sign PU2PLL -Brazil
 

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