kopia lustrzana https://github.com/peterhinch/micropython-nano-gui
DRIVERS.md add EPD micopower measurements.
rodzic
bfe679d169
commit
59629dd38c
29
DRIVERS.md
29
DRIVERS.md
|
@ -705,10 +705,31 @@ Users of other EPD's may want to develop other means of powering down the EPD.
|
||||||
A p-channel MOSFET could be considered as described
|
A p-channel MOSFET could be considered as described
|
||||||
[here](https://github.com/peterhinch/micropython-micropower/blob/master/HARDWARE.md#hardware-issues).
|
[here](https://github.com/peterhinch/micropython-micropower/blob/master/HARDWARE.md#hardware-issues).
|
||||||
|
|
||||||
In use I measured 500μA in the periods when the display is refreshing (a total
|
##### Measurements
|
||||||
of 10s for each wakeup) and 58μA between wakeups. The Pyboard accounts for
|
|
||||||
about 6μA. 33μA will be used by the 100KΩ pullup on the breakout's power enable
|
In use I measured 58μA between wakeups. The Pyboard accounts for about 6μA.
|
||||||
line. I haven't attempted to figure out where the other 19μA is going.
|
33μA will be used by the 100KΩ pullup on the breakout's power enable line. I
|
||||||
|
haven't attempted to figure out where the other 19μA is going.
|
||||||
|
|
||||||
|
I measured power consumption for a hypothetical application which wakes once
|
||||||
|
per hour, refreshes the screen, and goes back to sleep. In summary it uses
|
||||||
|
0.74AH per year. This suggests it could run for ~3 years on a set of alkaline
|
||||||
|
AA cells (capacity 2.5AH).
|
||||||
|
|
||||||
|
Of the total, the 58μA sleep current accounts for 0.5AH, and the wakeup current
|
||||||
|
0.24AH. Of the wakeup current, 28% is used for physical display refresh and a
|
||||||
|
further 39% during SPI transfer to the display. The remaining 33% is used by
|
||||||
|
boot (3%), initialisation of the device (2.8%), and initialisation of nano-gui
|
||||||
|
(27%). This is based on study of the current waveform in conjunction with
|
||||||
|
guessing what is going on in each phase of operation.
|
||||||
|
|
||||||
|
The measurements used frozen bytecode on a Pyboard D SF6W. No SD card was
|
||||||
|
fitted. Code was `epd29_lowpower.py` with the red LED code removed.
|
||||||
|
|
||||||
|
The fact that nearly 70% of the energy is used in standby suggests
|
||||||
|
improvements. If the EPD subsystem were turned off by a p-channel MOSFET,
|
||||||
|
current consumption could be reduced to the 6μA figure of the Pyboard, an order
|
||||||
|
of magnitude improvement.
|
||||||
|
|
||||||
###### [Contents](./DRIVERS.md#contents)
|
###### [Contents](./DRIVERS.md#contents)
|
||||||
|
|
||||||
|
|
Ładowanie…
Reference in New Issue