Startup power higher than while program running - why?

[flotulopex]

Hello,

I'm finishing my timer project and I have started to measure power consumption to correctly dimention the power supply on the final PCB.

When I power-up my circuit, the Amp-meter says 50mA. The timer is in some kind of idle mode since it waits for a player to start the timer or to choose the numbers of players.

When a button has been pressed, the current drops down to 19mA (!?) and stays around this value for all the time the game is ongoing.

In the START loop, pressing the RED button will ask the user to choose how many players will play. When it comes back to the initial display (still in the START loop), the current has dropped to 19mA (!?).

I can software reset the game (no power OFF) so the timer can come back to the very starting point of the program = same point as when the circuit is powered-on. The current goes then back to 50mA.

I assume something is wrong in my "START" loop.

Yes but what???

I had to attach the code in a .TXT file since it was to big to be fit in the post.

PS: it's my first "real" program so critics & comments are really welcome

[flotulopex]

So,

After a removed things one-by-one I could define that something is wrong with the Piezo speaker I have.

Originally, the piezo was connected directly to the PIC's pin with a 1µF cap in parallel with the piezo.

Since I removed the piezo, the current is constant at 19mA.

In the PBP Compiler Manual, it says that you can connect a piezo directly to the PIC. But the sound is not good (like saturated).

How do I have to connect my piezo a correct way?

[Luciano]

Hi,

Try first with 1μF and then with 10μF:



Best regards,

Luciano

[flotulopex]

Tchao Luciano,

The 1µF cap looks good! A 10µF one makes it even worse...

Still making some more tests...

Thanks a lot.

[Luciano]

Hi,

Disconnect the piezo from the microcontroller.
Connect the piezo to +5V via the 1µF DC blocking
capacitor and measure the current.

* * *

Connect the piezo to the microcontroller.
With an oscilloscope measure what you have
on the pin used to drive the piezo speaker.
(Measure when you don't hear the piezo speaker).

Best regards,

Luciano

[sougata]

Hi,

You mentioned that the current drops when you start the program and fall into the main loop. PBP does not inititialize a variable and it can have arbitary values. When you use the SOUND command for the first time it sets the data direction registers. (Actually it does it every time). So either initialize your variables,Data Direction Registers and PORT Latches or just use a short sound before you fall into the start loop. Do this without the cap and with it post the results.