Reading data on TX on USB Power Gauge Mini-Kit

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minwedar
 
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Reading data on TX on USB Power Gauge Mini-Kit

Post by minwedar »

I was playing with this new USB to TTL serial cable today and remembered seeing the USB Power Gauge Mini-Kit saying you can read data off the TX pin. I'm pretty new to this but was wondering if someone could tell what I'm doing wrong in seeing those reading. What I've done so far is download the 10.8 (I'm running Mountain Lion) serial driver for this USB to serial cable and when I plug it in I'm seeing it show up in my /dev list:

/dev/tty.NoZAP-PL2303-000032FD

I'm using the screen command to try to connect but I'm just getting a blank screen with no info coming through.
screen /dev/tty.NoZAP-PL2303-000032FD 9600 8N1

I've plugged the USB to TTL Serial cable into the USB Power Gauge Mini-Kit headers (Red-5V, Green-TX, and Black-GND) (white not plugged in since there is now RX header on the power gauge). Maybe my screen command is not quite right? Anyone using a mac have any suggestions?

From Adafruit description on the USB Power Gauge Mini-Kit:
"As an awesome extra, we also print out the voltage, current and wattage data as readable text on the TX pin at 9600 baud. Connect an FTDI friend, USB console cable, microcontroller, XBee, whatever you want that can read 9600 baud TTL serial data for datalogging, plotting or display."

USB Power Gauge Mini-Kit
http://www.adafruit.com/products/1549

USB to TTL Serial Cable - Debug / Console Cable for Raspberry Pi
http://www.adafruit.com/products/954

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adafruit_support_bill
 
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Re: Reading data on TX on USB Power Gauge Mini-Kit

Post by adafruit_support_bill »

There are four wires: red power, black ground, white RX into USB port, and green TX out of the USB port.
White is Rx with respect to the USB port. You want to connect that to the Tx coming from the power gauge.

http://www.adafruit.com/products/954#Technical_Details
There are four wires: red power, black ground, white RX into USB port, and green TX out of the USB port.

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minwedar
 
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Re: Reading data on TX on USB Power Gauge Mini-Kit

Post by minwedar »

Thank You! That makes sense now. And I noticed I don't need the 5V and GND either, just the the White RX on the TX pin and I'm getting readings.

Arduino
V: 5.5 I: 68 mA Watts: 0.4
V: 5.5 I: 66 mA Watts: 0.4
V: 5.4 I: 67 mA Watts: 0.4
V: 5.5 I: 66 mA Watts: 0.4
V: 5.5 I: 67 mA Watts: 0.4
V: 5.4 I: 67 mA Watts: 0.4
V: 5.5 I: 69 mA Watts: 0.4
V: 5.4 I: 67 mA Watts: 0.4
V: 5.5 I: 70 mA Watts: 0.4
V: 5.5 I: 62 mA Watts: 0.3
V: 5.5 I: 67 mA Watts: 0.4
V: 5.5 I: 70 mA Watts: 0.4
V: 5.4 I: 68 mA Watts: 0.4
V: 5.4 I: 67 mA Watts: 0.4

Plugging in iPhone:
V: 5.5 I: 0 mA Watts: 0.0
V: 5.2 I: 383 mA Watts: 2.0
V: 5.1 I: 717 mA Watts: 3.6
V: 5.1 I: 587 mA Watts: 3.0
V: 5.3 I: 414 mA Watts: 2.2
V: 5.3 I: 487 mA Watts: 2.6
V: 5.3 I: 297 mA Watts: 1.6
V: 5.3 I: 383 mA Watts: 2.0
V: 5.3 I: 192 mA Watts: 1.0
V: 5.4 I: 174 mA Watts: 0.9
V: 5.4 I: 169 mA Watts: 0.9
V: 5.4 I: 452 mA Watts: 2.4
V: 5.3 I: 208 mA Watts: 1.1
V: 5.4 I: 157 mA Watts: 0.8
V: 5.5 I: 157 mA Watts: 0.9
V: 5.3 I: 181 mA Watts: 1.0
V: 5.4 I: 207 mA Watts: 1.1

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adafruit_support_bill
 
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Re: Reading data on TX on USB Power Gauge Mini-Kit

Post by adafruit_support_bill »

And I noticed I don't need the 5V and GND either, just the the White RX on the TX pin and I'm getting readings.
Assuming that you are monitoring from the same computer, that should be fine. If for some reason you wanted to monitor using a different computer, you should at least connect the ground pin.

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wbp
 
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Re: Reading data on TX on USB Power Gauge Mini-Kit

Post by wbp »

I have a similar setup, USB Power Gauge and USB Serial cable. It works when both devices are plugged in to my PC, but I want to measure the current while the USB Power Gauge is plugged in to an external battery pack with a USB port. Using PuTTY with the same settings that worked with both plugged in to the PC, I don't get any text now. I metered the 5V pin and there is 5V (4.98, close enough).

Do I need to connect the red wire from the USB Serial cable? I wanted to check with you first so I don't fry anything... :-)

Thanks!
William

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wbp
 
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Re: Reading data on TX on USB Power Gauge Mini-Kit

Post by wbp »

I should add that I have only the green and white wires connected to the USB Power Gauge at the moment.

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wbp
 
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Re: Reading data on TX on USB Power Gauge Mini-Kit

Post by wbp »

Followup: don't know why the USB Serial Cable doesn't work, but I also have an FTDI Friend, so I hooked that up, connecting only ground and RX, and that works just fine.

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adafruit_support_bill
 
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Re: Reading data on TX on USB Power Gauge Mini-Kit

Post by adafruit_support_bill »

Do I need to connect the red wire from the USB Serial cable?
Ground and Rx should be sufficient. You don't want to be powering the device from two different sources at the same time.

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conurus
 
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Re: Reading data on TX on USB Power Gauge Mini-Kit

Post by conurus »

I am getting a "Not calibrated" message from the TX port. Is it supposed to be calibrated before it leaves the factory? If not what is the calibration procedure? Thanks.

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adafruit2
 
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Re: Reading data on TX on USB Power Gauge Mini-Kit

Post by adafruit2 »

Conurus, can you paste the exact output from the TX pin? and if you can, a photo of the power gauge? they outta be calibrated during test so thats unusual :)

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conurus
 
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Re: Reading data on TX on USB Power Gauge Mini-Kit

Post by conurus »

Code: Select all

ÿAdafruit USB Power Meter
Oct  1 2013
Not calibrated
It begins with a 0xff character. I bought two and they gave the same output.

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conurus
 
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Re: Reading data on TX on USB Power Gauge Mini-Kit

Post by conurus »

So, may I send it back for a calibration please?

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adafruit2
 
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Re: Reading data on TX on USB Power Gauge Mini-Kit

Post by adafruit2 »

please hold on another day - we wnat to make sure we have our test procedure in order so your replacement *is* calibrated :)

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conurus
 
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Re: Reading data on TX on USB Power Gauge Mini-Kit

Post by conurus »

Thank you! Are we ready yet?

But make no haste as even with only the LEDs they have already saved my butt on my design and I could not have been happier. I specifically need high side current monitoring with easy read out, and this is it!

It is just that, being a geek, I would like to explore more with the TX output. (Who wouldn't?)

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adafruit2
 
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Re: Reading data on TX on USB Power Gauge Mini-Kit

Post by adafruit2 »

ok lets try to send you another one - email support@adafruit with a link to this thread. still not sure whats up with yours! :)

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