[Tinyos-help] GIO1/ADC2 on Tmote

[Matt Thompson]

You can connect the GIO pin to a transistor to switch the sensors power 
supply on and off.  Or you can connect the ground of the device to the 
GIO pin, and sink the pin to turn it on.  If you put the pin in high 
impedance mode, the sensor will turn off (this is achieved by making the 
GIO pin an input).  Not sure how much current you can sink through the 
pin though, however it should be a lot more than it will source.

Cheers,
Matt

Joe Polastre wrote:
> ADC2 is output and low.
>
> GIO pins can only source ~2mA of current, so I don't recommend using
> them to power a device.
>
> -Joe
>
> On 9/3/06, Simon Davis <simondavis at mail.com> wrote:
>> Hello,
>>
>> I'm trying to use GIO1 as a power source for a sensor so I can turn 
>> it on and off to save power. If I put a voltmeter on the pad of R16 I 
>> get the battery voltage of about 3V appearing as it turns on. If I 
>> solder a 0ohm bridge on R16 to feed it to pin 7 of the 10 pin header 
>> (which is also used by ADC2), the voltage drops to about 1.3V and it 
>> draws over 30mA - this is without any load on pin 7.
>>
>> What am I doing wrong!? It's presumably something programmatic. I'm 
>> using TOSH_MAKE_GIO1_OUTPUT() and then turning it on and off with 
>> TOSH_SET_GIO1_PIN() and TOSH_CLR_GIO1_PIN(). Should I do something 
>> with ADC2 and why is the voltage dropping and 30mA being drawn?
>>
>> Many thanks
>>
>> Simon Davis
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> -- 
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