RF module power usage?

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22 May 2014 02:31 #23485 by ruzam
RF module power usage? was created by ruzam
I've successfully completed the diode range mod and added a XL7105-D03 RF module and a nRF24L01 RF module to my 7e. Both modules work and bind to respective receivers. Deviation v4.0.1

But I noticed my 7e battery life was now much shorter than it had been, so I started measuring current draw and found some surprising results.

Using a DSMX config the transmitter was drawing 250 mA. Way more than it should be. So I removed both the extra RF modules (cut them free) and measured again.

The stock transmitter (with the diode range mod) draws only 70 mA (150 mw setting). That's a huge difference from the 250 mA being used when the other RF modules were installed.

So I added back just the nRF24L01 and measured again.

With the extra nRF24L01 RF module, when I power up the 7e with a DSMX model set, the transmitter draws 220 mA! When I power up with a HiSky (nRF24L01) model set, the transmitter only draws 90 mA.

For some reason the internal board RF module jumps from 70 mA to 220 mA simply by having the extra nRF24L01 installed. Yet, when powered up with a HiSky (nRF24L01) model configured, it only draws 90 mA. So it doesn't even add up to two modules being powered at the same time (not even counting the power being used by the transmitter CPU).

There's something wrong with the initial power up state of the transmitter internal RF circuit when combined with an additional RF module.

And it gets stranger.

If I switch to a HiSky (nRF24L01) model 'after' power up, the current draw jumps to 130 mA. So where as it was only 90 mA at power up, it's now 130 mA if the model config was switched.

If I switch to the internal DSMX model 'after' power up, the current draw is only 160 mA. It was 220 mA at power up.

The internal RF module uses less power when it's switched, the additional nRF24L01 RF module uses more power when it's switched. Together they use significantly more power than the stock transmitter.

I'm a little worried about the change in power up/switched power usage. That's telling me something is not initialized or reset properly. I don't understand how the transmitter can suddenly be using 'more' power than the total of either RF module alone.

Are the RF modules being disabled when not in use? They should be drawing mere micro amps when not in use.

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22 May 2014 03:11 - 22 May 2014 03:11 #23487 by PhracturedBlue
Replied by PhracturedBlue on topic RF module power usage?
In 4.01 module may or may not be in low power mode when not in use. In the nightly builds this should be resolved, and all modules not in use should be in low power mode.
A power-amp can peak out at 350mA, but will typically draw ~100mA at full power. Note that the Devo7e has the PA disabled unless you do the diode mod, so its power usage is not high.
The MCU can use ~150mA (though generally it will use less)
The screen with backlight can get to ~100mA (most of that is backlight) if I remember correctly.
Last edit: 22 May 2014 03:11 by PhracturedBlue.

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22 May 2014 04:00 #23488 by ruzam
Replied by ruzam on topic RF module power usage?
I'll have to try the nightly and see if anything changes.

I don't know about the screen, but the backlight is less than 10mA (I suspect the LCD is much less).

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22 May 2014 06:38 #23493 by yidc
Replied by yidc on topic RF module power usage?
I have a similar setup and find that battery also draining fast
remote: 7e(4.0.1 build 2f438bf) w/ diode range mod and 3x2 switch mod
extra RF: nRF24L01+PA+LNA

let me also conduct the same test and upload the results afterwards.

P.S. maybe it's better to measure current drain from each extra RF module as well?

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22 May 2014 16:58 #23506 by ruzam
Replied by ruzam on topic RF module power usage?
OK, updated to the nightly devo7e-v4.0.1-f90c1d5

Things are better, but still not quite right.

The nRF24L01 draws 80 mA now (including backlight and the rest of the transmitter power usage). It's draws the same amount, whether it's the module configured when the transmitter powers up, or if I switch to it later. I think that's appropriate. I think it also indicates that the onboard RF is being shut down when not in use.

But the onboard RF remains a problem. If I power up with a DSMX model, the power draw is still 190mA. If I 'switch' to a DSMX model, the power draw is 130mA (still too high). There's something not right between the difference of powering up and switching to the onboard RF.

Maybe it's not the onboard RF, but a problem with nRF24L01 not shutting down and/or being initialized differently on power up?

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23 May 2014 00:51 #23512 by VTdev
Replied by VTdev on topic RF module power usage?

PhracturedBlue wrote: ......
The screen with backlight can get to ~100mA (most of that is backlight) if I remember correctly.


I checked the 7e battery draw with the backlight on, and checked again when it went off. It only changed by 7 ma.

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23 May 2014 00:56 #23513 by VTdev
Replied by VTdev on topic RF module power usage?
Also, my (range diode modded) Tx has the low level buzzing sound sometimes. I have no modules aboard and only use DSM2 protocol.

While monitoring the current usage the buzzing started and current nearly doubled. Sometimes if you hit a trim button, the buzzing stops. I did and it worked, and the current dropped back to normal. Later I got the buzzing again, and could confirm that the current again increased to the same amount.

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23 May 2014 14:52 - 23 May 2014 14:52 #23529 by aMax
Replied by aMax on topic RF module power usage?
Did you measure the current draw when the buzzer is switched on or off?
It would take my interest.

The backlight draws very little. From level 5 to 1 or
even off, no change in voltage level displayed from Devo7e.

But, I have this buzzing noise too
So I switched the buzzer off, there was a gain of 0.06 Volts.
I have four 2400mAh NiMH in the box and they should easily fight this.
So I changed my configuration from Buzz to Vibration.

I did the diode mod, have 3x2 switches, a 7105-D03 on board, use version v4.0.1-ac4f0b2.
It would be nice if the buzzer is deactivated from Deviation by default, until it is time to buzz.....

Devo7e, TaranisQ X7, R9M , 4in1 MM, Futaba FC18plusV3.2 & DFT/FLD-02
Last edit: 23 May 2014 14:52 by aMax.

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23 May 2014 20:09 - 23 May 2014 20:10 #23540 by VTdev
Replied by VTdev on topic RF module power usage?
aMax,

Deviation build is devo7e-v41-6a63c8e.
Buzz volume was set to 10.
Vibration was set to off.

Diode range mod installed. (conductive ink)
Two 3-way switches added.
No Modules added.
Last edit: 23 May 2014 20:10 by VTdev.

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23 May 2014 21:25 #23543 by ruzam
Replied by ruzam on topic RF module power usage?
I've also noticed that since I've switched to f90c1d5, the model transmitter power config simply says 'default' with no way to change it from the menu.

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24 May 2014 01:38 #23550 by aMax
Replied by aMax on topic RF module power usage?
@ruzam
You have to enable the PA in hardware.ini (has_pa-cyrf6936 = 1 )
Since several releases of the 7e_nightlys, it is disabled by default.

@VTdev
This ink, it seems to work well enough.
I applied a lot of effort to replace the diode by a small smd bridge from an old nVidia card.

Devo7e, TaranisQ X7, R9M , 4in1 MM, Futaba FC18plusV3.2 & DFT/FLD-02

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24 May 2014 02:53 #23551 by ruzam
Replied by ruzam on topic RF module power usage?

aMax wrote: @ruzam
You have to enable the PA in hardware.ini (has_pa-cyrf6936 = 1 )
Since several releases of the 7e_nightlys, it is disabled by default.


Yes, that's the trick. Thanks, I missed that after the upgrade


The comments in the hardware.ini are a little confusing:

; there is no need to enable the cyrf6936 module unless
; it is wired to an alternate port. It is Enabled automatically otherwise

I realize now that it's referring to enable-cyrf6936, not has_pa-cyrf6936, but confusing none the less.

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