NRF24L01+PA+LNA power consumption

[Jokgi]

What is the PA used on the board? Are there schematics available? (Or a part number for the board) Are they using the VDD_PA line from the nRF24L01P to enable the PA? If so, scope out the VDD_PA line and see if it is toggling when transmitting. It will go high 50us before the nRF24L01p transmits a packet and will stay high the full time it is transmitting. If that line is not toggling when sending packets then you are not transmitting.

[Oitzu]

@Jokgi: https://www.squirrel-labs.net/wp/wp-content/uploads/2015/02/nRFa.jpg
I think that is what most of the boards are doing. But i also seen schematics in wich the 1kOhm resistor isn't there.
So there could maybe be problems if you try to control the nrf24l01+ PA/LNA with a 5V Arduino because the PA can't handle the 5V signal.

[Jokgi]

@Oitzu
Is that the released schematic for that Module?
I can see why they have the resistor removed.
The CE line is a active high input to the nRF24L01P. The RXEN is a input to the RFX2401C used to switch in the different modes. (See the mode select table below)
The CE line could / should be controlled by the host MCU. You can see this on the state machine in the nRF24L01P datasheet section 6.1.1, Figure 4. The diagram shows recommended operating modes vs. possible operating modes.

For the RFX2401C,,,,
If the RXEN is pulled high with a resistor and when the nRF24L01P is not transmitting, the unit will switch the LNA in. In this setup the RFX never goes to shut down mode and the RFX is either in TX or RX mode. There are no internal pull ups or pull downs on the nRF24L01P CE or or the RFX devices RXEN. Therefore there is no guaranty that the lines will be high or low and could be subject to noise. I would not leave them floating.

Control Logic Truth Table X= Don't Care
TXEN RXEN 0perating Conditions
1 X TX Active
0 1 RX Active
0 0 Chip is Shut-down

To address the Current Draw. According to the RFX2401C datasheet, when the PA is transmitting at 20dBm the current consumption of the amp is 120mA. Plus whatever else you have running. (MCU, nRF24L01P, etc)

[parachutesj]

@Jokgi
Thank you. I am using this http://rover.ebay.com/rover/1/711-53200-19255-0/1?icep_ff3=2&pub=5575069610&toolid=10001&campid=5337433187&customid=&icep_item=310651702557&ipn=psmain&icep_vectorid=229466&kwid=902099&mtid=824&kw=lg

Datasheet link is broken...

[Oitzu]

@Jokgi hard to say to which module excatly it belongs.. would need to track the traces on the pcb to be 100% sure.
Isn't CE pulled down by the MCU while not transmitting or receiving? I do not have really any problems with the module going power down.

@parachutesj Well i got most problems with this sort of module, if you have the one pictured.
They tended to not run at all without adding a grounded shield, add the LC-Filer and maked sure to run the signals with 3.3V.

[Jokgi]

@Oitzu The pictures I have seen of various PA modules available on EBAY and such show a pretty solid ground pour on the top and bottom of the module. I am surprised that wrapping them with Au foil helped much. (But stranger things have been known to work. ;-) ) Does anyone have some quantitative numbers with and without the foil mods?

[Jokgi]

@Jokgi @ all. Sorry I was not specific. I should have added Range measurements with and without the foil.

[Oitzu]

@Jokgi it may be true that the ground filling seems to be quite good, but it seems like it needs also be shielded.
Without the shielding the module is influenced by its own signals and external signals.
There are also modules out there that have actually a shield added: http://www.aliexpress.com/item/Shielding-Case-10pcs-lot-nRF24L01-PA-LNA-wireless-communication-modules-with-antenna-2-4GHz-2Mbps-1000m/851058052.html
But i have not tested them yet.

By quantitative numbers you mean range?
On max transmitting power i don't got even 5meters because the PA TX seems to overload the RX and ack will never be received.
With the shielding i got arround 1000 meters free line of sight.

[parachutesj]

@Oitzu
I got the new ones in the mail today. those are the shielded ones from IC station (http://www.icstation.com/22dbm-100mw-nrf24l01ppalna-wireless-transmission-module-p-4677.html)
but even here when measuring current it never goes higher than 31mA
I am going nuts. I mean I should be happy about the low power consumption but I think I haven't set them up correctly and not getting the full power.

Again, I set in MyConfig.h

#define RF24_PA_LEVEL 	   RF24_PA_MAX
#define RF24_PA_LEVEL_GW   RF24_PA_MAX

and my constructor:

MyTransportNRF24 radio(RF24_CE_PIN, RF24_CS_PIN, RF24_PA_LEVEL);

I am measuring with a Fluke 87V and just making sure also took another one reading similar values.
I ran the VCC through my multimeter - any ideas?

[Oitzu]

@parachutesj i'm reading pretty much the same values on my multimeter, so nothing to worry about. ;)

[parachutesj]

@Oitzu I just thougt that others reported 115mA and more.
However the module with the shielding says 100mW that would make at 3.3v exactly 30.3 mA... So actually yes, all correct

[Jokgi]

@Oitzu Thanks for the follow up. Yes, the CE line is a input to the nRF24L01P. In the schematic sent yesterday it showed the CE line connected to the RXEN of the RFX2401c. Both are inputs.

[Jokgi]

@parachutesj Unless you have the transmitter in constant carrier mode you cannot successfully measure the current with a standard multi-meter. If you want to know if the radio is transmitting and you have a good scope then look at the VDD_PA line.

[Oitzu]

@parachutesj as Jokgi said, you can't measure correctly the current of the modules with just a multimeter, you are losing peaks in the process.
Did you tried yet how far the shielded versions of the module reach? Would be great to have some sort of comparision. :+1:

[parachutesj]

@Oitzu
I do not have the equipment to measure the reach, I just noticed that some spots in the house seem to be covered which haven't been before. However this might be just because of different antenna placement.

[AWI]

To demonstrate what happens I made some measurements on the NRF24L01+PA+LNA power consumption. The nano in the setup runs a simple sketch which sends one value every 100ms and sleeps in between (RF24_PA_MAX).

First is the setup with a standard nRF24L01+ (working clone ;-) ) The current meter measures the current in the power line of the radio (before the regulator to avoid side effects) and has an internal resistance of 3.4 Ohm. The measured current is a kind of random average sample and shows around 4 mA.

Now look at the waveform of the same current on the scope. I circled the radio send current. The level of pulse is around 70mV which translates to ~20mA (0.07 V/ 3.4 Ohm)

Second is the setup with a the nRF24L01+PA+LNA(working clone ;-) )

and the waveform on the scope.. around 700mV translates to ~200mA (0.7V/ 3.4.Ohm) 10 times as much and no comparison to the (random average sample) reading on the current meter of ~22mA (a Fluke meter does not change this ;-))

[Mark Swift]

@Oitzu said:

https://www.squirrel-labs.net/wp/wp-content/uploads/2015/02/nRFa.jpg

Guys,

I also use the base module to connect my NRF24 radios, I recently received 2 of the shielded PA+LNB modules but don't see much difference using them. The issue I have is that I need to hold the module for it to be reliable :( Once I let go, the transmission slows and becomes unreliable (I experienced the same with the unshielded modules).

Is the base module okay to use wit the PA+LNB modules, I was concerned that someone said the module cannot use 5v control lines?

[AWI]

@Mark-Swift The "base plate" gives you a solid 3.3v for the radio and sufficient decouple/ bypass capacitors. i recognized there is a lot of variety in all kinds of radiio's even if these look similar. That's the reason I built this meter.
For shielding make sure you connect the shield to ground. A lot has been published on performance of these modules.

[Mark Swift]

I'm using these modules, I presume the base unit is compatible? I was confused when I read above that the PA modules may need a 3v control line.

http://www.icstation.com/22dbm-100mw-nrf24l01ppalna-wireless-transmission-module-p-4677.html

I'm really frustrated that none of my modules work unless I physically hold them, even the shielded ones above!

[AWI]

@Mark-Swift High frequency transmission is a kind of dark science... ;-) I had the same experience you had with the 'expensive' shileded modules. The best performance upto now I have with my own shielding on the PA modules (plastic and aluminum tape/foil) powered by the adapter board and connected to a stable 5v supply.