Showing posts with label raspberry pi. Show all posts
Showing posts with label raspberry pi. Show all posts

Wednesday, June 17, 2020

Raspberry PI 3 Model B Rev 1.2 Power Wattage

My order of USB power meter arrived a few days ago, but only today I could put it into use by plugging it in between the power supply adapter and my RPI.

The way I test the max power consumed is by creating a small C program to do infinite loop such as:

int main()
{
   while (1) {}
}

I executed it in four separate processes (open four terminals, and run the program in each one). This way I could exhaust the whole four cores in the CPU.  I also GUI desktop on the machine (LXDE).

Here what is shown by "top":




My USB power meter shows 1.17 WH, meaning in each hour it consumes 2.37 Watt or 0.00237 KWh.  If the price per kWh charged by Utility company is 12.01 cent ($0.1201/KWH), in a day I'd pay 0.00237 KWh* $0.1201/KWh * 24 hours = $‭0.006831288‬ or about $0.0068 per day.  In a month I'd pay about $0.2 minimum.

After I killed all those four infinite loop processes, the wattage did not drop.  Instead I saw it climbed to almost 2 Watt-hour.  I think over time it probably would drop back to around 2 W (idling time).

Thursday, March 28, 2013

Raspberry Pi Rev 2.0 Pin headers

Got my new Raspberry Pi mode-B rev 2.0 yesterday.  After looking around the info about some new unpopulated through holes on it, finally I got all the info.  Here's the summary:

Silkscreen label: P2
It is a 1x8-pin connection for JTAG to the main SoC (Broadcom MCU).
Silkscreen label: P3
It is 1x7 pins to be used for JTAG header connected to the USB hub + ethernet chip.
Silkscreen Label: P5
2x4 pins.  It's for extra connection
Pin 1 (square solder plate): +5 V output
Pin 2: +3.3v
Pin 3: GPIO28 (can be configured as I2C's SDA)
Pin 4: GPIO29 (can be configured as I2C's SCL)
Pin 5: GPIO30 
Pin 6: GPIO31 
Pin 7 and 8: Ground

Silkscreen label: P6
1x2 pins.  For MCU reset (short them will reset the MCU)

By the way, here is the info about the board (I have no idea my the Hardware below shows BCM2708, not BCM28xx):

pi@raspberrypi ~ $ cat /proc/cpuinfo
Processor    : ARMv6-compatible processor rev 7 (v6l)
BogoMIPS    : 464.48
Features    : swp half thumb fastmult vfp edsp java tls
CPU implementer    : 0x41
CPU architecture: 7
CPU variant    : 0x0
CPU part    : 0xb76
CPU revision    : 7

Hardware    : BCM2708
Revision    : 000e
Serial      : 00000000xxxxxxxx