TTL, voltage, one-wire test rig

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An undergraduate EE student is tasked with creating a test rig for environmental sensors connected to a data logger, aiming to troubleshoot incorrect data readings from sensors like the MB7380 ultrasonic sensor. The rig must evaluate various signal types (TTL, analog voltage, 1-wire) and provide outputs to test connections and logger inputs. Suggestions include using a simple user-friendly device for non-technical users, possibly incorporating a known good sensor for comparison. The discussion emphasizes the importance of understanding communication paths, signal integrity, and potential electrical noise in the field. A straightforward Go/NoGo test set is recommended for ease of use in a production or QA environment.
  • #31
adamaero said:
All I can find on the Q4 datalogger are instruction manuals, not datasheets.
Does it specify SPI datarates anywhere? Sorry if you already posted it and I missed it.
 
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  • #32
berkeman said:
Does it specify SPI datarates anywhere? Sorry if you already posted it and I missed it.
"6 GPIO pins and also contains a High Speed UART, SPI bus and I2C Bus"

"Includes 2X High Speed 3.3V (5V Tolerant) TTL Serial Ports, 1X High Speed SPI Interface, 1X I2C Interface with onboard pullups, 8X GPIO Pins"

I can ask the company for a numerical value.
  1. Is "high speed" is a specific value?
  2. Also, why SPI? Is this one SPI? Why isn't it UART?
  • GPIO5/UART2_RX/SPI_IN
 
  • #33
Yeah, asking the manufacturer might be a good idea, and also ask if there are any back-termination resistors included on their high-speed communication lines.
 
  • #34
Designing from the top, down;
After building a data logger you can plug in your 'test unit' to monitor functionality and QC.
In the field you can connect your 'test unit' to diagnose faults that may be present.

You will need to tap into each data logger's circuits in a number of places to check operation. That must be done without disturbing the unit under test. You could insert an extra plug&socket tap as a wedge between existing mated connectors. That would not be convenient with screw terminals.

The alternative would be to provide a standard external field test connector that gives access to the majority of internal connections on all the data loggers built. Your test unit can then evolve as further tests are developed during the manufacturing and testing phases.
 
  • #35
Baluncore said:
Designing from the top, down;
After building a data logger you can plug in your 'test unit' to monitor functionality and QC.
...
Yes, that's the easy part.

berkeman said:
... communication lines.
It's only a few feet. The site is remote, but powered by solar panels. Transmission line effects are negligible.
 

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