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 Ticker changer;
00015 int count=1;
00016 
00017 DigitalIn sw(p5);
00018 PwmOut led(p25);
00019 
00020 void change(){
00021     count = count << 1;
00022     if (count > 0x08) count = 0x01;
00023     if (1) {
00024         for (float p = 0.0f; p < 1.0f; p += 0.1f) {
00025                led = p;
00026                wait(0.1);
00027         }
00028     }
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     
00039     //PHY_PowerDown();
00040  
00041 // If you don't need the PC host USB interface....
00042 // Power down magic USB interface chip - saves around 150mW
00043 // Needs new firmware (URL below) and USB cable not connected
00044 // http://mbed.org/users/simon/notebook/interface-powerdown/
00045 // Supply power to mbed using Vin pin
00046     //result = semihost_powerdown();
00047 // Power consumption is now around half
00048  
00049 // Turn off clock enables on unused I/O Peripherals (UARTs, Timers, PWM, SPI, CAN, I2C, A/D...)
00050 // To save just a tiny bit more power - most are already off by default in this short code example
00051 // See PowerControl.h for I/O device bit assignments
00052 // Don't turn off GPIO - it is needed to blink the LEDs
00053     //Peripheral_PowerDown(0xFFFF7FFF);
00054  
00055 // use Ticker interrupt and Sleep instead of a wait for time delay - saves up to 70mW
00056 // Sleep halts and waits for an interrupt instead of executing instructions
00057 // power is saved by not constantly fetching and decoding instructions
00058 // Exact power level reduction depends on the amount of time spent in Sleep mode
00059     changer.attach(&change, 0.0625);
00060     while (1) {
00061         Sleep();
00062     }
00063 }