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how much is the normal current consumption in sleep and normal operating in PIC16F1829 ?

arvinfx

Member
HI

Is it normal to have 25ma current consumption when all ports configured as input??
and also the chip is some kind of warm when I touch it by finger.
Crystal is external 28Mhz.
VDD =4V
 
Last edited:

MacIntoshCZ

Active Member
Last edited:

Nigel Goodwin

Super Moderator
Most Helpful Member
I just notice that when the chip is Blank erased even 25mA current is consumed !!!
It's obviously not in sleep mode if it's blank, so it's running at full speed - which with a 28MHz crystal will be quite current heavy if it's running from that?. Although I'm not sure what the default fuse settings are?.

Also don't configure pins as inputs if they are floating, as this will cause excessive consumption.
 

arvinfx

Member
I have done something and i am amazed!!
I desolded the PIC16F1829 and out of the board it takes 40ma!!! So i try to measure the resistor between vdd and vss, it was 85ohms !!!
But also chip is working probably!!! What is this?
 

MacIntoshCZ

Active Member
The think is the chip is out side of the board now plz read the post no.7
So the think is: chip is defective or your programmer is shity as your circuitry. Dont take this offensive...
 

schmitt trigger

Well-Known Member
As Nigel has mentioned, setting ports as inputs and leaving them open will cause the processor to draw lots of current.
If you are going to leave unconnected pins, set them as ports. If a pin is always an input, use a 10k resistor to ground.

I have used several Microchip controllers, and when properly set up the current draw in sleep mode is lower than what can be measured with even a good handheld DMM.
One requires a bench top DMM with sub micro amp resolution to measure it.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
I have used several Microchip controllers, and when properly set up the current draw in sleep mode is lower than what can be measured with even a good handheld DMM.
One requires a bench top DMM with sub micro amp resolution to measure it.
I do a LOT of low current PIC devices, and have never been able to approach the claimed consumption - it's low, but nowhere near as low as the datasheets claim.

I now use a 'Current Ranger' device to monitor the consumption, which is far better than a multimeter on low currents.
 

MacIntoshCZ

Active Member
Hi NG, can i ask why power consumption is high when pins are set as input? I though it can only sense voltage in input mode and sink/source current in output mode. But i am not much into microcontrollers. thanks
 

rjenkinsgb

Well-Known Member
Most Helpful Member
why power consumption is high when pins are set as input?
It applies to many CMOS type devices.

The basic input circuit configuration is typically something like this:



If the input is held high or low, one transistor is on and the other off; no current flows.
If the input is allowed to float, both transistors can be partly on and continuously pass current.

With an MCU, setting an unused pin to output means the input on the same pin is either high or low, so gets around the problem without extra components.
 

schmitt trigger

Well-Known Member
That was exactly my point Nigel, that one requires a sensitive instrument and not a plain DMM to measure standby current.
And definitely 25 mA is large enough for even the cheapest DMM to measure.
 

arvinfx

Member
With an MCU, setting an unused pin to output means the input on the same pin is either high or low, so gets around the problem without extra components.
I have read this in an application note of Microchip, If I set all unused pins to output is it necessary to set them to 0 or 1 or just config them to output?
 

MacIntoshCZ

Active Member
I have read this in an application note of Microchip, If I set all unused pins to output is it necessary to set them to 0 or 1 or just config them to output?
i think if you set pin to 1 it will enable pull up / down resistor. But i dont remember exactly.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
I have read this in an application note of Microchip, If I set all unused pins to output is it necessary to set them to 0 or 1 or just config them to output?
Just configure them as outputs (TRIS = 0) - it makes little difference if they are high or low - in fact there was a heated argument on the PICLIST way back last century about which was best. Essentially there's little difference, and different PIC's could be different - hence no real answer to the argument.
 

arvinfx

Member
I have to buy a new PIC16F1829 chip and test it ,will release the result here , but the think is really unusual for me is that why with this kind of damage my PIC chip is working totally fine!!!
before this also I had some experience with bad pin in a PIC16F819 , That it was config as input but eventually that pin dead! afther around 1 year or 1.5 years but anything else on that chip was working fine! after all I had to change the chip to a brand new.
 

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