Mon, Nov 28, 2022 at 12:27:08PM +0000, Richard F wrote:
FYI I'm using the powersaving patch on a system with an Astrometa USB
stick + an old Winfast PCI receiver, and I see 2-3W reduction when the
Astrometa frontend is shut down:
I only tested with a single receiver. Your patch may very well switch
off any additional receivers, but it seems to me that one front-end
would always remain enabled.
Today, I measured the power consumption again, with the Pi TV HAT
attached, but without an aerial cable. The setup is a bit flimsy; like
last year, the Raspberry Pi is displaying an undervoltage warning icon
on the top right corner. I do not dare to over-volt the power supply.
For comparison, I am quoting my figures from last year, without the Pi
TV HAT, and with/without the Astrometa stick:
I measured the following current draw at 5 volts, in ascending order:
81 mA: Raspberry Pi 2B shut down
127 mA: Raspberry Pi 2B + TV HAT shut down
200 mA: Raspberry Pi 2B powered up, no Ethernet plugged in
240 mA: Ethernet cable plugged in (HDMI cable makes no difference)
256 mA: Ethernet cable plugged in; Pi TV HAT attached
267 mA: Ethernet + HDMI plugged in; Pi TV HAT attached
320 mA: Ethernet + USB DVB stick plugged in
440 mA: compiling VDR with "make -j4" (all CPU cores busy)
480 mA: compiling (peak; sometimes as low as 300 mA)
550 mA: VDR playing back a recording
530 mA: recording paused in VDR
510 mA: EPG scan running
600 mA: VDR displaying live DVB-T2
440 mA: VDR started up, blank screen (no aerial plugged in)
510 mA: VDR playing back a recording (peak value)
450 mA: recording paused in VDR
This time, I did not plug in an aerial cable at all. I would guess that
displaying live TV would consume at most 550 mA.
As you can see from the above, the idle consumption is about 260 mA.
When VDR is seemingly idle, I am seeing additional consumption of around
200 mA.
Notably, after I killed the vdr process, the power consumption would
hover around 330 mA. It could be that my version of rpihddevice is not
properly shutting down all processes on the Videocore IV GPU. After I
restarted the VDR process, I got a similar power consumption as above.
While it does not like we can blame the active tuner for all of the
additional consumption of 200 mA, I think that we can attribute at least
100 mA to it. The difference between 260 mA and 450 mA is +70%, not
insignificant.
I am glad to see that the Pi TV HAT is consuming less power than the
Astrometa stick. It is logical, because the TV HAT does not have to run
an additional 8051 microcontroller and a step-down SMPS to produce 3.3V
from the 5V USB supply, and presumably at least one separately packaged
memory chip.
But I'm still running V2.20 and have a workaround for the 2 frontends
on the Astometa - both for reasons mentioned before on this list.
Yes, I remember the frontend-swapping issue on the Astrometa. It may
have been fixed in 2.6. I didn't try the Astrometa stick on my Pi after
reinstalling Raspberry OS Legacy from the scratch.
Marko
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