jim hamblen
A blink LED demo with power management to reduce power.
main.cpp@0:02d7e850d7cb, 2011-01-28 (annotated)
- Committer:
- 4180_1
- Date:
- Fri Jan 28 17:31:00 2011 +0000
- Revision:
- 0:02d7e850d7cb
Who changed what in which revision?
| User | Revision | Line number | New contents of line |
|---|---|---|---|
| 4180_1 | 0:02d7e850d7cb | 1 | #include "mbed.h" |
| 4180_1 | 0:02d7e850d7cb | 2 | #include "PowerControl/PowerControl.h" |
| 4180_1 | 0:02d7e850d7cb | 3 | #include "PowerControl/EthernetPowerControl.h" |
| 4180_1 | 0:02d7e850d7cb | 4 | // Need PowerControl *.h files from this URL |
| 4180_1 | 0:02d7e850d7cb | 5 | // http://mbed.org/users/no2chem/notebook/mbed-power-controlconsumption/ |
| 4180_1 | 0:02d7e850d7cb | 6 | |
| 4180_1 | 0:02d7e850d7cb | 7 | // Function to power down magic USB interface chip with new firmware |
| 4180_1 | 0:02d7e850d7cb | 8 | #define USR_POWERDOWN (0x104) |
| 4180_1 | 0:02d7e850d7cb | 9 | int semihost_powerdown() { |
| 4180_1 | 0:02d7e850d7cb | 10 | uint32_t arg; |
| 4180_1 | 0:02d7e850d7cb | 11 | return __semihost(USR_POWERDOWN, &arg); |
| 4180_1 | 0:02d7e850d7cb | 12 | } |
| 4180_1 | 0:02d7e850d7cb | 13 | |
| 4180_1 | 0:02d7e850d7cb | 14 | DigitalOut myled1(LED1); |
| 4180_1 | 0:02d7e850d7cb | 15 | DigitalOut myled2(LED2); |
| 4180_1 | 0:02d7e850d7cb | 16 | DigitalOut myled3(LED3); |
| 4180_1 | 0:02d7e850d7cb | 17 | DigitalOut myled4(LED4); |
| 4180_1 | 0:02d7e850d7cb | 18 | |
| 4180_1 | 0:02d7e850d7cb | 19 | Ticker blinker; |
| 4180_1 | 0:02d7e850d7cb | 20 | int count=1; |
| 4180_1 | 0:02d7e850d7cb | 21 | |
| 4180_1 | 0:02d7e850d7cb | 22 | void blink() { |
| 4180_1 | 0:02d7e850d7cb | 23 | count = count << 1; |
| 4180_1 | 0:02d7e850d7cb | 24 | if (count > 0x08) count = 0x01; |
| 4180_1 | 0:02d7e850d7cb | 25 | myled1 = count & 0x01; |
| 4180_1 | 0:02d7e850d7cb | 26 | myled2 = count & 0x02; |
| 4180_1 | 0:02d7e850d7cb | 27 | myled3 = count & 0x04; |
| 4180_1 | 0:02d7e850d7cb | 28 | myled4 = count & 0x08; |
| 4180_1 | 0:02d7e850d7cb | 29 | } |
| 4180_1 | 0:02d7e850d7cb | 30 | |
| 4180_1 | 0:02d7e850d7cb | 31 | int main() { |
| 4180_1 | 0:02d7e850d7cb | 32 | int result; |
| 4180_1 | 0:02d7e850d7cb | 33 | // Normal mbed power level for this setup is around 690mW |
| 4180_1 | 0:02d7e850d7cb | 34 | // assuming 5V used on Vin pin |
| 4180_1 | 0:02d7e850d7cb | 35 | // If you don't need networking... |
| 4180_1 | 0:02d7e850d7cb | 36 | // Power down Ethernet interface - saves around 175mW |
| 4180_1 | 0:02d7e850d7cb | 37 | // Also need to unplug network cable - just a cable sucks power |
| 4180_1 | 0:02d7e850d7cb | 38 | PHY_PowerDown(); |
| 4180_1 | 0:02d7e850d7cb | 39 | |
| 4180_1 | 0:02d7e850d7cb | 40 | // If you don't need the PC host USB interface.... |
| 4180_1 | 0:02d7e850d7cb | 41 | // Power down magic USB interface chip - saves around 150mW |
| 4180_1 | 0:02d7e850d7cb | 42 | // Needs new firmware (URL below) and USB cable not connected |
| 4180_1 | 0:02d7e850d7cb | 43 | // http://mbed.org/users/simon/notebook/interface-powerdown/ |
| 4180_1 | 0:02d7e850d7cb | 44 | // Supply power to mbed using Vin pin |
| 4180_1 | 0:02d7e850d7cb | 45 | result = semihost_powerdown(); |
| 4180_1 | 0:02d7e850d7cb | 46 | // Power consumption is now around half |
| 4180_1 | 0:02d7e850d7cb | 47 | |
| 4180_1 | 0:02d7e850d7cb | 48 | // Turn off clock enables on unused I/O Peripherals (UARTs, Timers, PWM, SPI, CAN, I2C, A/D...) |
| 4180_1 | 0:02d7e850d7cb | 49 | // To save just a tiny bit more power - most are already off by default in this short code example |
| 4180_1 | 0:02d7e850d7cb | 50 | // See PowerControl.h for I/O device bit assignments |
| 4180_1 | 0:02d7e850d7cb | 51 | // Don't turn off GPIO - it is needed to blink the LEDs |
| 4180_1 | 0:02d7e850d7cb | 52 | Peripheral_PowerDown(0xFFFF7FFF); |
| 4180_1 | 0:02d7e850d7cb | 53 | |
| 4180_1 | 0:02d7e850d7cb | 54 | // use Ticker interrupt and Sleep instead of a wait for time delay - saves up to 70mW |
| 4180_1 | 0:02d7e850d7cb | 55 | // Sleep halts and waits for an interrupt instead of executing instructions |
| 4180_1 | 0:02d7e850d7cb | 56 | // power is saved by not constantly fetching and decoding instructions |
| 4180_1 | 0:02d7e850d7cb | 57 | // Exact power level reduction depends on the amount of time spent in Sleep mode |
| 4180_1 | 0:02d7e850d7cb | 58 | blinker.attach(&blink, 0.0625); |
| 4180_1 | 0:02d7e850d7cb | 59 | while (1) { |
| 4180_1 | 0:02d7e850d7cb | 60 | Sleep(); |
| 4180_1 | 0:02d7e850d7cb | 61 | } |
| 4180_1 | 0:02d7e850d7cb | 62 | } |