main.cpp

00001 #include "mbed.h"
00002 #include "PowerControl/PowerControl.h"
00003 #include "PowerControl/EthernetPowerControl.h"
00004 // Need PowerControl *.h files from this URL
00005 // http://mbed.org/users/no2chem/notebook/mbed-power-controlconsumption/
00006 
00007 // Function to power down magic USB interface chip with new firmware
00008 #define USR_POWERDOWN    (0x104)
00009 int semihost_powerdown() {
00010     uint32_t arg;
00011     return __semihost(USR_POWERDOWN, &arg);
00012 }
00013 
00014 DigitalOut myled1(LED1);
00015 DigitalOut myled2(LED2);
00016 DigitalOut myled3(LED3);
00017 DigitalOut myled4(LED4);
00018 
00019 Ticker blinker;
00020 int count=1;
00021 
00022 void blink() {
00023     count = count << 1;
00024     if (count > 0x08) count = 0x01;
00025     myled1 = count & 0x01;
00026     myled2 = count & 0x02;
00027     myled3 = count & 0x04;
00028     myled4 = count & 0x08;
00029 }
00030 
00031 int main() {
00032     int result;
00033 // Normal mbed power level for this setup is around 690mW
00034 // assuming 5V used on Vin pin
00035 // If you don't need networking...
00036 // Power down Ethernet interface - saves around 175mW
00037 // Also need to unplug network cable - just a cable sucks power
00038     PHY_PowerDown();
00039 
00040 // If you don't need the PC host USB interface....
00041 // Power down magic USB interface chip - saves around 150mW
00042 // Needs new firmware (URL below) and USB cable not connected
00043 // http://mbed.org/users/simon/notebook/interface-powerdown/
00044 // Supply power to mbed using Vin pin
00045     result = semihost_powerdown();
00046 // Power consumption is now around half
00047 
00048 // Turn off clock enables on unused I/O Peripherals (UARTs, Timers, PWM, SPI, CAN, I2C, A/D...)
00049 // To save just a tiny bit more power - most are already off by default in this short code example
00050 // See PowerControl.h for I/O device bit assignments
00051 // Don't turn off GPIO - it is needed to blink the LEDs
00052     Peripheral_PowerDown(0xFFFF7FFF);
00053 
00054 // use Ticker interrupt and Sleep instead of a wait for time delay - saves up to 70mW
00055 // Sleep halts and waits for an interrupt instead of executing instructions
00056 // power is saved by not constantly fetching and decoding instructions
00057 // Exact power level reduction depends on the amount of time spent in Sleep mode
00058     blinker.attach(&blink, 0.0625);
00059     while (1) {
00060         Sleep();
00061     }
00062 }