Do you have TARGET_VDD on pin 1 or not?
Yes, this pin of the JTG connector is connected to 3V1 on my board and the programmer
When do you say "H7" and mention a PMIC - are you referring to a Portenta H7 board?
(which provides power as pin 1 for VDD just after bootloader/FW has configured PMIC)
Yes, the Portenta H7 from Arudino. Indeed it does provide power on this pin AFTER the communication is achieved with the MCU and the boot loader is uploaded. I am not able to achieve the fundamental task of connect to the MCU, so boot loader and PMIC programming are not performed at this stage.
- is TARGET_VDD provided on JTAG header pin 1 after PMIC configured? (or already as VDD needed to boot your MCU?)
Yes, voltage on VDD is provided after the MCU is booted.
- Do you say, you cannot download any MCU FW and therefore not doing the PMIC config?
(and therefore not VDD on pin 1? Are you in a "chicken and egg issue"?)
VDD pin on the JTAG connector on the Portenta H7 has 0 volts during chip erase and boot loader programming process. This works fine and I have done it quite a few times to test the process. This also works as I've said before, with the VDD wire completely cut. I did it again 3 times today also and with an oscilloscope connected to confirm that the VDD pin on the programmer AND board stay at 0V, when the VDD wire is cut in half.
So no chicken or egg. The chip is connected and programmed, then when the MCU boot loader is working, it programs the PMIC to deliver 3V1 to the components connected to this supply line.
MCU power comes from PMIC 3V1. this is not connected to the JTAG VDD or 3V1 lines.
- Sure, if pin 1 on JTAG as TARGET_VCC (T_VCC) and programmer is not there - debugger does not see your target.
That seems to be the case on my board, but on the H7 the programmer sees the MCU without any problem.
Try to run debugger in "connect in low power mode", in "connect under reset" etc.
I just tried that, also without success.
Again: if you have any VDD, e.g. for MCU alive on board, and you are sure the MCU is powered (and out of reset): just use a jumper wire and provide VDD on pin 1: grab it from the same VDD used on MCU (so that MCU can boot, even PMIC no configured yet, the VDD which powers MCU for boot).
Or: even provide 3V3 (as target VDD) from something else, e.g. your external 5V for main power input (with a resistor divider).
I am still convinced: your JTAG adapter to programmer does not see a VDD on pin 1.
At the moment the JTAG adaptor definitely does not see VDD on pin #1, it is cut so that the programmer doesn't not inject 5V into my board. But, this does not seem to be a problem for the portenta H7. With this wire cut in half, the portenta H7 connects, erases and programs without any problems.
I tried to connect the 3V1 and VDD lines together wirth the programmer connected, but it injected 5V into the 3V1 (MCU power) line and potentially damaged the MCU.
I have just sent the board back for rework to replace the MCU so am reluctant to try this again. Something on one of the other pins is making the programmer inject 5V on the VDD line so am focussed on the other lines at the moment.
Do you reference to a NUCLEO-H7 board (e.g. the NUCLEO-H743ZI2)?
No, the Arduino portenta H7. We share the same design for MCU, PMIC and JTAG connection.
Have you tried with a patch wire to bring target VDD to pin 1?
Yes, see above. When the programer is connected, VDD has 5V on it from the programmer. When I connect the VDD wire to my board, it raises the voltage on VDD to 5V. If I short the MCU power (3V1) to the VDD pin, it raises the MCU power to 5V.
Show us your schematics.
I can share our schematics via direct message. The Portenta H7 schematics are freely available on the Aruduino website.
