What's the power consumption of a PIC chip in reset?

[2camjohn]

Hey Guys.

I had a question that I couldnt work out using the datasheet.

Im currently designing something with the 16f630.
If I hold it in reset by pulling MCLR to ground, is the power consumption reduced like its in sleep mode?

If so, I could save a pin and a little code on my design which would be really handy.

Cheers
John

 

[Sceadwian]

No reset is not the same as sleep mode, not sure what the energy usage in reset is cause you're not really supposed to do that.

 

[Mr RB]

I believe it's very similar to sleep mode. The oscillator shuts down, the PORT pins go high impedance etc. The power consumption *should* be very similar to sleep mode. A quick test with a multimeter set to microamps would give a better answer...

 

[kpatz]

You can always program the MCLR pin to be an input with wake-on-pin change and implement the sleep in your code. Then you know the chip is actually "asleep" when you pull the pin low.

 

[Sceadwian]

If you do that you can't use ICSP can you?

 

[kpatz]

If you do that you can't use ICSP can you?

Yes you can... even if the pin is programmed as an input instead of MCLR it still works as the Vpp pin (high voltage on it puts the chip into programming mode).

You just have to make sure not to put more than Vdd on it when used as an input, or the chip will enter programming mode in your application.

 

[Sceadwian]

High voltage programming is not ICSP programming. Especially not if that high voltage fries the sensor you were attaching to that input...

 

[Nigel Goodwin]

High voltage programming is not ICSP programming. Especially not if that high voltage fries the sensor you were attaching to that input...

ICSP can be either high or low voltage programming, but in the VAST majority of cases it would be high voltage.

As with any ICSP design you need to design it properly, so that the programming system doesn't affect anything else.