Previous to using the MBED, I spent several years using the PIC and using sleep mode, started designing battery operated projects. e.g. an egg timer whose battery's (2 x AAA) have so far lasted 4 years.!
Today I experimented with the mbed connected to the QVGA LCD display from Mikroelectronica.
Used PWM o/p for led backlight via 5R resistor and digital I/O to supply Vcc to the display.
Used a 3v6 lithium battery with the +ve lead connected directly to the 3V3 regulator on the mbed.
Also removed the blue power indicator LED ( 2ma ).
After displaying a test screen on the display I ended the software with:
()clear screen on LCD
()PWM o/p zero (LED backlight off)
()digital I/O cleared to zero (power to LCD off)
()deepPowerDown (Sleep)
Hooking up my Keithley rs232 multimeter I measured a current consumption of 3 mA
and once the mbeD was in sleep a consumption of 5.78 microamps.
the lithium battery voltage is now connected to the Keithley data logger and over the last hour the voltage has dropped from 3.750 to 3.749 volts.
Is there anything else I can do,either in software or hardware to reduce the 'sleep' discharge current
to less than 1 microamp?
Previous to using the MBED, I spent several years using the PIC and using sleep mode, started designing battery operated projects. e.g. an egg timer whose battery's (2 x AAA) have so far lasted 4 years.!
Today I experimented with the mbed connected to the QVGA LCD display from Mikroelectronica. Used PWM o/p for led backlight via 5R resistor and digital I/O to supply Vcc to the display.
Used a 3v6 lithium battery with the +ve lead connected directly to the 3V3 regulator on the mbed. Also removed the blue power indicator LED ( 2ma ).
After displaying a test screen on the display I ended the software with:
()clear screen on LCD ()PWM o/p zero (LED backlight off) ()digital I/O cleared to zero (power to LCD off) ()deepPowerDown (Sleep)
Hooking up my Keithley rs232 multimeter I measured a current consumption of 3 mA and once the mbeD was in sleep a consumption of 5.78 microamps.
the lithium battery voltage is now connected to the Keithley data logger and over the last hour the voltage has dropped from 3.750 to 3.749 volts.
Is there anything else I can do,either in software or hardware to reduce the 'sleep' discharge current to less than 1 microamp?