Hi，

  This may be due to poor communication,you can check usb data cable, and chip power supply,

I think I found out the reason, but I still can't understand why.

When I supply the chip from 3.7V battery, through the voltage regulator with 3V output - measured voltage is 2.97V. I get the error.

When, instead of battery, I connect supply from the programmer. And it goes through the same voltage regulator and output voltage is also 2.97V. But programming works.

Any idea why?

What is the minimum voltage requited for programming?

I had a look at supply voltage from the programmer when you click ACTIVATE button. Here is the picture.

So, when I have battery connected I don't get this voltage pulse.So maybe Swire is not OK with battery?

And here is another strange thing.

Here is the power supply circuit in my device:

I connect the programmer 0V and SWS to the USB socket. Switch SW1 is on - the chip is supplied from battery - Programming fails.

I turn the switch off (the battery supply to the chip is off). The only wires that are connected to the chip are 0V and SWS (so the chip is supplied through SWS). Programming works.

I tried this a couple of times and it works every time.

I am happy that it works this way, otherwise I wouldn't be able to flash the chip. Note all this applies to the device with Power Management enabled, because that s when you have problems with Swire - when device is asleep.

Any explanation to this?