Low voltage on Arduino

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Issue #13 new
Jonas Follesø created an issue

Sorry for spamming you guys with issues - but I feel I'm so close to getting this thing working!

I've made a power cable using a power adapter where you can set the output voltage using jumpers. I've connected it to terminal strip as if it were the battery.

If I measure the voltage at J1, I get 15v as expected. How ever, if I measure voltage between the VCC and GRD pins on the Arduino, it only has ~2.0V, and the red light is "flickering".

Also - as mentioned in issue #12 there is power on the Cam out (J3) - but it's only ~8-9V.

In my previous testing I've had the Arduino connected to the PC using the FTDI cable, which provides power directly to the Arduino (and then the power has been ~4.2V - which got me thinking that it might not be a good idea to run it on both power, and power it through USB at the same time...?)

Any ideas to why the Arduino voltage is only ~ 2.0V when providing the board with 15V? Is the power supply perhaps not providing enough current (it outputs 1500mA at 14.0V)

Comments (8)

  1. Chad Kecy

    Check J2 on the controller board. It determines the Vdd level on the board (based on the variety of Arduino you have 3.3 or 5). Don't ever power up the controller board without J2 installed. Check to make sure the fuse, F1, is good and installed all the way. Something is pulling the BATT bus down. Wait, is your supply drawing 1.5A all the time? It shouldn't be. Your current consumption will go up while the camera and lights are on, but with just the controller/arduino, it should be 10's of milliamps at 14V. I think like 60-70ma. If you're drawing 1.5A at all times, you might have a short somewhere. Disconnect all the cables to the board and make some resistance measurements (BATT to Gnd, Vdd to Gnd) and look for an obvious low ohm reading (hopefully not!)

  2. Chad Kecy

    Oh, and keep the Issues coming! It's great for us to get feedback. Although in this case, you may have an actual problem.

  3. Jonas Follesø reporter

    I've checked the fuse, F1, and it is connected - not sure how to check if it's good or not... Also, the 1.5A mentioned in my original post was simply the output capacity of the power supply, not actuall current measured on the board.

    The Arduino Controller Shield Hardware Interface reference document states:

    • Install a 2-pin shunt jumper on J2. Pins 1-2 for 5V Arduinos
    • Pins 2-3 for 3.3V Arduinos

    J2 has three pins and they are not numbered, so it's not obvious if you cound from top/bottom on J2. Might be an improvement in the documentation. But I've installed a jumper on J2, pin 2-3 (counting from the top).

    • Measuring voltage at the terminal strip at the battery side, the voltage is ~14V.
    • Measuring voltage at J1 on the camera side, the voltage is ~14V.
    • Measuring voltage at C3 on the camera side, the voltag is ~3.2V (so the J2 pin is set correct I assume?)
    • Measuring voltage at J6 RAW and GRD pins is ~14V (isn't that too high for RAW power on the Arduino?)
    • Measuring voltage at J6 VCC and GRD pins is 0V

    So to re-iterate, the problem is that if I simply provide power to the board, without the FTDI cable connected, the red power LED on the Arduino Pro Mini is flickering. So it's like it's not getting enough power?

  4. Jonas Follesø reporter

    To simplify testing I disconnected all cables from the shield, and connect the shield directly to the power supply. So I have the shield, the Arduino and a power supply. The red power LED is still flickering.

  5. Jonas Follesø reporter

    Looking in the Controller Shield documentation for J6 it states that JP6 pin #1 is the RAW input power. If I measure it it is ~14V (which is higher than recommended for the Arduino Pro Mini - should be between 3.2 and 12V for the RAW pin, right?)

    Should the JP6 pin provide 3.2V or 5.0V (based on the J2 pin settings). Could this be the problem?

  6. Jonas Follesø reporter

    This StackExchange question discusses the input voltage of the Arduino Pro Mini 3.3V: http://arduino.stackexchange.com/questions/750/arduino-pro-mini-3-3v-version-input-voltage-range-tolerance

    "The genuine Pro Mini's use a MIC5205 regulator which should accept up to 16V at it's input normally, with an absolute maximum of 20V. It's unlikely that the regulator would be damaged by 15.1V."

    So 14V input at the RAW pin should be okay (but still interested to know if the JP6 pin #1 is supposted to be regulated to 3.2V)

  7. Jonas Follesø reporter

    I have a spare Arduino Pro Mini, and when connecting it to the shield it powers up (i.e. no flickering on the power LED) - which makes me wonder if I might have damaged something on the first Arduino Pro Mini.

    I have not tried uploading the source code to the second Arduino Pro Mini (only powering it up) - will try that later today to see if the problem simply is a faulty Arduino Pro Mini.

  8. Chad Kecy

    Yes, we tested with our battery volts on RAW and never had a problem (the Arduino has it's own regulator onboard). So J6-1 should read your battery voltage (14V in this case). We did this so either variety of Arduino (3.3 or 5) could be used.

    We were running out of room for silkscreening, so J2 didn't get labeled. However, if you look at the back of the board, you can identify pin 1 as the square pad (holds true for all of the connectors).

    Try uploading code to the suspect Arduino separately from the controller board; hopefully that will take care of the problem!

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