MI6 Power Management
We use the standard 1500 mAh NiCd battery to run our MI6. The power available is:
7.2 V*1500 mAh8 hours =1350 mW
For components, in general:
All the power will go through a 5V voltage regulator, and this 5V source will supply Tiva, a shift register, a coin sensor, a Bluetooth module, and two seven segments display. At the same time, xbee and two joysticks will draw current from 3.3V regulated voltage supply on Tiva. All buttons are connected to pull-up enabled IO pins, which does not consume power. The screen is an android phone from ZTE, and it has a separate voltage supply can make it last 8 hours for our application.
Shift Register, 74ACT595 (Although it sinks current to drive seven segments, we count it next)
Pdiss=Vdd*Idd
Pdiss=5V*80 ϻA=0.4 mW
Seven Segments Display, We used two seven segment module and all LED bars on one module share a 1k resistor. The forward voltage for LED is about 2V.
Idd= Vdd- VfR=5V- 2V1kΩ=3 mA
Pdiss=Vdd*Idd
Pdiss=5V*3 mA=15 mW
Coin Sensor, H21A1,
Emitter:
Idd= Vdd- VfR=5V- 1.2V220Ω=17.2 mA
Pdiss=Vdd*Idd
Pdiss=5V*17.2 mA=86 mW
Receiver:
From data sheet Ic (on)is about 1 mA.
Pdiss=Vdd*Ic (on)
Pdiss=5V*1 mA=5 mW
Bluetooth Module, RN-42
Pdiss=Vdd*Idd
Pdiss=5V*40 mA=200 mW
Tiva LaunchPad
At 40 MHz with room temperature, with all peripherals on, the Idd is about 32 mA.
Pdiss=Vdd*Idd
Pdiss=3.3V*32 mA=105 mW
Xbee
Pdiss=Vdd*Idd
Pdiss=3.3V*50 mA=165 mW
Joystick
Idd= VddR=3.3 V10kΩ=0.33 mA
Pdiss=Vdd*Idd
Pdiss=3.3V*0.33 mA=1.1 mW
5V voltage regulator, LM7805
Quiescent Current is 5 mA.
Since linear voltage regulator used, it will dissipate power like voltage divider did. As we currently only care the total consumption, I will directly calculate it with the total current. The total power consumption will be our supply voltage 7.2V times all current needed.
Total Current = 80 ϻA+2*3 mA+17.2 mA+ 1 mA+ 40 mA+ 32 mA+ 50 mA+ 0.33 mA*2+5 mA=152 mA
Total Power Consumption = Total Current * 7.2 V = 1094 mW < 1350 mW
Yes, the MI6 can run over 8 hours.
7.2 V*1500 mAh8 hours =1350 mW
For components, in general:
All the power will go through a 5V voltage regulator, and this 5V source will supply Tiva, a shift register, a coin sensor, a Bluetooth module, and two seven segments display. At the same time, xbee and two joysticks will draw current from 3.3V regulated voltage supply on Tiva. All buttons are connected to pull-up enabled IO pins, which does not consume power. The screen is an android phone from ZTE, and it has a separate voltage supply can make it last 8 hours for our application.
Shift Register, 74ACT595 (Although it sinks current to drive seven segments, we count it next)
Pdiss=Vdd*Idd
Pdiss=5V*80 ϻA=0.4 mW
Seven Segments Display, We used two seven segment module and all LED bars on one module share a 1k resistor. The forward voltage for LED is about 2V.
Idd= Vdd- VfR=5V- 2V1kΩ=3 mA
Pdiss=Vdd*Idd
Pdiss=5V*3 mA=15 mW
Coin Sensor, H21A1,
Emitter:
Idd= Vdd- VfR=5V- 1.2V220Ω=17.2 mA
Pdiss=Vdd*Idd
Pdiss=5V*17.2 mA=86 mW
Receiver:
From data sheet Ic (on)is about 1 mA.
Pdiss=Vdd*Ic (on)
Pdiss=5V*1 mA=5 mW
Bluetooth Module, RN-42
Pdiss=Vdd*Idd
Pdiss=5V*40 mA=200 mW
Tiva LaunchPad
At 40 MHz with room temperature, with all peripherals on, the Idd is about 32 mA.
Pdiss=Vdd*Idd
Pdiss=3.3V*32 mA=105 mW
Xbee
Pdiss=Vdd*Idd
Pdiss=3.3V*50 mA=165 mW
Joystick
Idd= VddR=3.3 V10kΩ=0.33 mA
Pdiss=Vdd*Idd
Pdiss=3.3V*0.33 mA=1.1 mW
5V voltage regulator, LM7805
Quiescent Current is 5 mA.
Since linear voltage regulator used, it will dissipate power like voltage divider did. As we currently only care the total consumption, I will directly calculate it with the total current. The total power consumption will be our supply voltage 7.2V times all current needed.
Total Current = 80 ϻA+2*3 mA+17.2 mA+ 1 mA+ 40 mA+ 32 mA+ 50 mA+ 0.33 mA*2+5 mA=152 mA
Total Power Consumption = Total Current * 7.2 V = 1094 mW < 1350 mW
Yes, the MI6 can run over 8 hours.