MSP430-JTAG-ISO-MK2 Low power supply on USB

Started by el_guapo, April 06, 2018, 11:23:07 AM

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Got one of these yesterday - great product.

I am trying to power it using a USB power supply (non pc) to see if it is possible to use a 2A USB powerbank for mobile use.

When I power via the USB cable from a PC USB2/3 port, the JTAG-ISO works as normal.

However when I connect it to any USB power supply (not a PC) then I mostly get a "Low power supply Apply ext. power" message.  I tried four different supplies both desktop and powerbank - all were 1-2A rated outputs but same result on all.

A few times - but not clear why or what was different - it powered as normal but I did not try connecting to a device.

Is this possible - or does it generally rely on the USB data connection to allow the 5V supply? 

Best Regards



Hello Des,

I tested without USB data lines (used our USB-ISO convertor without any USB input, only power input). I set the unit in stand alone mode and read and programmed my target Olimex MSP430-P2274 board. It worked fine. Refer to my hardware setup, I uploaded a picture here:

Then I tested with another adapter, that would probably look like the ones you got and managed to get the same error message as you. This is the second method of powering the unit via the USB: – so how did I manage to remove the error message? I did the hardware connections in different order – disconnected the target from the board (the JTAG connection) and first powered MSP430-JTAG-ISO-MK2, then after it turned on I connected the target. It seems that the target might have capacitors on the power input that might cause a voltage drop if both the emulator and the target have to be powered.

Also if the problem persists, consider that the best idea for stand-alone powering is to use the provided +12V DC jack. Did you try powering the board from the +12VDC jack at the top? You can find information about our jacks here:

> Is this possible - or does it generally rely on the USB data connection to allow the 5V supply?


Best regards,
Technical support and documentation manager at Olimex