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Powering TWR-VF65GS10 with Tower USB and using I-Jet via IAR

Question asked by Keith Smith on Jul 31, 2015
Latest reply on Aug 4, 2015 by Keith Smith

I am using IAR with an I-Jet JTAG device working with the TWR-VF65GS10.


If I plug-in the I-Jet into 20-pin JTAG connector J5 and attempt to debug a program, IAR says the CPU is not powered.


This correct, the I-Jet does not supply power to the Vybrid board.


Now I connect a USB cable to the Tower primary board, the Vybrid board powers up and runs its program. The 4 colored LEDs flash in sequence.


If the I-Jet is then connected, IAR still says that the CPU is not powered.


Below are the power values from the EmuDiag program of the I-Jet.


Channel #0 (ITrgPwr): 0uA

Channel #1 (VTrgPwr): 8.058mV

Channel #2 (VTRef): 3281.465mV

Channel #3 (VUser0): 3030.036mV

Channel #4 (VUser1): 3023.589mV

Channel #5 (VUSB5V): 4981.831mV


Reading TWRVF65GS10UG.pdf, section 2.3.1 discusses how to power the TWR-VF65GS10.


Section states "The J19 is fully open and J25 closed in this mode, and the 5V power comes either from the Tower elevator USB connector or the screw terminal,

The J18 state does not matter thanks to the on-board 3.3V DC switch (see section ."


This tells me to remove J19 if I want the TWR-VF65GS10 to be powered from the primary board.


However, IAR debugging still tells me 'CPU did not power up'.




if I disconnect the USB cable from the primary board and install J6 and enable 'Target Power' in IAR/I-Jet settings, the power LED, D9, is lit, but still I get 'CPU did not power up'.


I am using the default jumper settings as documented in the TWR-VF65GS10 Quick Start Guide, except as discussed above. (J6 and J25).


If I plug a USB cable into J3, the I-Jet debugger works.


Is it always required that I supply power to J3? If not, what am I doing wrong?