measuring rail currents on a board

MicroChip? Their M7 (ATSAMV70/V71) is really nice as are their M0s. MicroChip is our microcontroller manufacturer of choice.

People I trust are using a lightweight RTOS, like ChiBios or NuttX. Evaluating those is one of my next steps.

CH

Did Microchip have any ARM products before they bought Atmel? I seem to recall they had their own architectures (plural) and at least one chip based on the MIPS architecture, but no ARMs of their own. No?

No one has suggested the following and, not being an "expert", I'm curious as to why.

The I2C controlled switchers estimate the current by reading the voltage across the FETs when they are on. Solder a coax cable across the lower FET and use a scope to get an idea of the current going it with a scope.

Also add a DC load to each supply, it will enable you to find out how much headroom each supply has and to calibrate the above measurements.

As I said, my 10cents, curious to know if its worth 10cents.

I prefer to use the controllers that can startup and work at the correct voltages without requiring software intervention or any sort of ISP. This allows me to decouple the hardware and software development.

The monitoring and fault diagnosis is really handy for manufacturing tests.

Regards, Allan

I meant variable DC load of course.

I'm using tiny TI synchronous switchers, TPS54302, and I could measure the ON (or even OFF) fet voltage drop and estimate current. So that's another way to do it. It's a 3 amp switcher, so at my low load currents it would be a tricky measurement. The sawtooth current in the inductor is probably a lot bigger than the load current.

It would work at more usual currents.

One trick in any current measurement kluge is to add some known load on the output, to calibrate the measurement scheme.

So far, we've mostly done state-machine based bare-metal. Two projects so far are Linux on ZYNQs. My programmer guy is considering using an RTOS on the ST processors, which I don't much like, but I'll let him do what he likes. He sure gets stuff done.

Please let us know what you learn. I'll do the same.

We usually include a BIST facility on a board, which includes acquiring and reporting all the power supply voltages closed-box. Reporting currents would be cool too, so I guess interfaced regulators sort of make sense.

We do check overall box power drain (most of our stuff is powered by the VME bus, or 24 DC) so any outrageous currents would show up there.

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Provided the RTOS has a nice API and is fully pre-emptable, I think you'd have to have a *very* good reason not to use one.

For recommendations, see who uses what, and look at their taste in coding and hardware design.

The excellent PX4 autopilot software uses Nuttx:

The Pecan Pico high-altitude balloon trackers use ChiBios:

I had no idea that ordinary folk launch balloons that stay aloft for months while circling the globe.

Clifford Heath.

If you can measure the overall input, perhaps you can selectively enable / disable parts of the board and record the DELTA at the input. From this info you can deduce what each section draws.

Correct. They did the PICs (8, 16, 24, 32). It's all MicroChip now, so...

The ting I don't understand is their part numbers for the ARMs start with PIC now. Dumb.

snipped-for-privacy@notreal.com wrote in news: snipped-for-privacy@4ax.com:

Go with NXP or Marvell.

No.

Their MIPS parts also start with PIC

It seems like they're still trying to convince people that their 8-bit PIC parts were RISC.

But they always did, no? Aren't they the PIC32s?

I think they're just trying to confuse people. I've talked several their FAEs (and higher up the food chain) ears off but they just shrug. I'm not the only one who doesn't like it.