Estimote GPIOs output current


#1

I’m working on a project that I’ve to make the Estimote interfaces a comparator circuit so I can read a small input value in terms of 800~900 mV and I made some tests and reached that Estimote can sense the high state when the input level reaches 1.2V and the low state when the input level reaches 600mV, in between it remains on the previous state.
So I need to take the GPIO0 to drive the comparator supply and its reference input using a voltage divider and use GPIO1 to read the value of the comparator’s output.
Now I’ve 2 constrains, the voltage divider current at the reference input AND the comparator supply itself.
Unfortunately, I can’t find any HW Description Document for Estimote GPIOs!
I hope if there’s anyone can help me out to know the maximum output current per GPIO pin.


#2

I searched for the Estimote controller and I found in its datasheet that the GPIOs can source/sink 0.5mA and there are 3 pins with high-drive option that can source/sink 5mA, so I was wondering about GPIO0 and GPIO1 are connected to which category?

Also there are 2 resistors are connected between the controller and the GPIOs and these resistors should drop some current, so I wan wondering too about their values so I can measure the exact current which I can source/sink using GPIO0 & GPIO1


#3

After careful research, and regarding the 2nd picture on previous reply, taking a look on the controller notch I found that GPIO0 & GPIO1 are connected to pins’ numbers: 14 & 15 which are P0.08 & P0.09 and regarding the following link:
https://devzone.nordicsemi.com/question/31394/number-of-nrf51822-high-drive-pins/
I discovered that any pin can be programmed to be a high drive pin, so my question is:
Are GPIO0 & GPIO1 programmed to be high drive pins?


#4

I’m more of a software than hardware guy myself, but … does this spec help?

GPIO specs - Location Beacon.pdf (42.2 KB)

Pretty impressive to see you trying to figure this out all on your own, sorry for making you do that!


#5

Well, the document is good but it doesn’t state the output current from GPIO0 & GPIO1 too.
My problem now is that I reached to the output current but it’s based on how you programmed it first time in Nordic Controller, so I hope if someone can confirm to me either they programmed to be high-drive or standard-drive GPIOs.
That’s will help :slight_smile:


#6

As I couldn’t find an answer regarding the current and for spreading knowledge, I used a CMOS comparator to avoid current consumption for powering-up the comparator and I used a very high resistors’ values in the potential divider which typically consumes 28.6uA and my circuit successfully worked!


#7

True hacker’s spirit (:

I can’t help but ask now: what are you building? (;


#8

Well, I’m trying to sense small signal of sensors’ network and use the mesh technique of the estimote, after some researches regarding the estimote hardware, I figured that estimote can give you a high state at 1.2V input and low state at 0.6V input and in between it remains on the previous state, my network was working on high level from 0.5 up to 0.9V so I used to use a level shifter but unfortunately I don’t have a supply circuit and I can’t build one regarding the environment of the sensors so I had to use something can be powered-up from estimote itself and does not drain its battery, which was a comparator circuit with special design that can drain a very quiescent current which won’t drains the estimote’s battery, also via the estimote I’ve the ability to switch on and off this circuit so the system will work only at the measurement time which repeated with long periods of time!
Now, I’m using the both GPIOs, one for supplying the circuit and the other one to sense the sensors’ output.


#9

Nice, thanks for sharing! (:


#10

Hi…what i know is in the output mode, beacon delivers data to the connected device via GPIO. You could for example switch a LED lamp on or off with the beacon controlled from a mobile app.
In this configuration, the beacon will deliver data from two pins about their binary states to the connected device.