Q2686 Power consumption calculation


#1

Hi guys,

I developed an application for my Q2686 wireless module and I downloaded it to the CPU so that it automatically runs every time it is requested to (eg when pushing a button). I would like to do a rough theoretical calculation of the power consumption of my application but I am a bit confused using the tables from the product specification datasheet. My application uses GPRS to connect to the internet and send packets to a server. In addition, it also sends SMS. My problem is that I am not sure which tables and values to use for my calculations:

  1. When my CPU does nothing but wait (eg waits to press the button), is it idle mode fast/slow? Should I use the table with the Open At processing or not? Is it the table for @26MHz or @104MHz?

  2. I also have the same inquiries when the module uses GPRS and GSM services (at 1800/1900 MHz). Which values should I use from the tables?

Please guys, I would appreciate much your help!

Cheers
Tatiana


#2

Why do you think your CPU does nothing until you press a button?

You should not use any tables since your application already developed. Plug multimeter into module’s power source and check the current into different working modes. You will get all answers.


#3

Well, yes, this is to be done as a next step, but I need to compare the theoretical calculations with actual measurements!


#4

If you need theoretical values - you should let us know how you get your module to sleep while waiting for button press.


#5

Actually I didn’t use any sleep mode, although it would save power to my final circuit configuration. The GSM module remains in idle mode when no button is pressed. But what about GSM consumption when sending an SMS and GPRS consumption when sending GPRS packet to a server? Could you please help me with this?


#6

Take a look in PTS for your module. Part 3.2.2.2 Power consumption with OpenAT processing. When your module does nothing but stays in connected mode, it consumes minimal current (PCL19) which is 90mA in average. I could not find more information but I guess that if the gsm cover in that area is bad than consumption could increase up to maximum (PCL5) up to 200 mA. During SMS send or call you will get peak consumption which is from 270 mA to 1450 mA.

All of this is for GSM900.

If you use GPRS use values from Transfer Mode consumption, which depends of GPRS class you use. Every time you send in GPRS class 10 you will get consumption up to 1450 mA.


#7

Hi,
I have designed the new board , but its not working…
pls some help me…
The details of new design are. https://forum.sierrawireless.com/t/connections/3947/1

regards
Ravee