CARRIERs SCAN PROCEDURE With nRF24L01+

RE: CARRIERs SCAN PROCEDURE With nRF24L01+

Håkon Alseth — Fri, 31 Aug 2018 07:15:30 GMT

Hi,

Thanks for the example code.

You need to wait atleast 130 us (Ramp-up time) before reading the RPD bit, and I would also recommend reading this prior to disabling the RX. Could you try this and see if you get the expected result?

Best regards,

Håkon

RE: CARRIERs SCAN PROCEDURE With nRF24L01+

LPO — Thu, 30 Aug 2018 18:20:33 GMT

Thanks Hakon for your support,
but need understand as this RPD bit is detected as one easy secuence or flowchart mode.
I work in assembler and don't understand well C, but I had found one C secuence than is possible can run, if you can explain it terms as I explain at the top of this Nordic Case Info.

Thanks,
LPO

-----------------------------------------
The source code I found is:
-----------------------------------------
#define CE 9

#define CHANNELS 64 // Define as array to hold channel data
int channel[CHANNELS];

#define _NRF24_CONFIG 0x00 // Registers 0x00
#define _NRF24_EN_AA 0x01 // Registers 0x01
#define _NRF24_RF_CH 0x05 // Registers 0x05
#define _NRF24_RF_SETUP 0x06 // Registers 0x06
#define _NRF24_RPD 0x09 // Registers 0x09

// Get the value of the NRF25L01 Registers
byte getRegister(byte r)
{
byte c;
PORTB &=~_BV(2);
c = SPI.transfer(r&0x1F);
c = SPI.transfer(0);
PORTB |= _BV(2);

return(c);
}

// set the value of a nRF24L01p register
void setRegister(byte r, byte v)
{
PORTB &=~_BV(2);
SPI.transfer((r&0x1F)|0x20);
SPI.transfer(v);
PORTB |= _BV(2);
}

void powerUp(void) // power up the nRF24L01p chip
{
setRegister(_NRF24_CONFIG,getRegister(_NRF24_CONFIG)|0x02);
delayMicroseconds(130);
}

// switch nRF24L01p off
void powerDown(void)
{
setRegister(_NRF24_CONFIG,getRegister(_NRF24_CONFIG)&~0x02);
}

void enable(void) //Activate RX
{
PORTB |= _BV(1);
}

void disable(void) //Deactivate RX
{
PORTB &=~_BV(1);
}

// setup RX-Mode of nRF24L01p
void setRX(void)
{
setRegister(_NRF24_CONFIG,getRegister(_NRF24_CONFIG)|0x01);
enable();

// this is slightly shorter than
// the recommended delay of 130 usec

delayMicroseconds(100);
}

//SCANNING ALL CHANNELS IN 2.4GHz Band

void scanChannels(void)
{
disable();
for( int j=0 ; j<200 ; j++)
{
for( int i=0 ; i<CHANNELS ; i++)
{
// select a new channel
setRegister(_NRF24_RF_CH,(128*i)/CHANNELS);

// switch on RX
setRX();

// wait enough for RX-things to settle
delayMicroseconds(40);

// this is actually the point where the RPD-flag
// is set, when CE goes low
disable();

// read out RPD flag; set to 1 if
// received power > -64dBm
if( getRegister(_NRF24_RPD)>0 ) channel[i]++;
}
}
}

RE: CARRIERs SCAN PROCEDURE With nRF24L01+

Håkon Alseth — Thu, 30 Aug 2018 07:43:36 GMT

Hi,

[quote user="LPO"][/quote]

The nrf24L01+ product specification V1.0 on page 25 expain as detect the carrier bit RPD, in one contradictory form:
"The RPD can beread out at any time while nrf24L01+ is in receive mode" and "If no packects are received the RPD is
latched at he end of a receive period as result the host MCU setting CE low"
If I put at end of a receive period CE low, I am no't in receive mode as is writed in first part this specification.

Other question is what mean "a receive period", what time is this ?
And they are others conditions ?

The first sentence states that you can read the RPD at any time while in receive mode, and it will reflect what the receiver sees in terms of signal level.

The second sentence is referring to the latched state of the RPD while you are not in RX mode.

I tested this by setting up a unmodulated carrier at channel 40, then using a nRF24LE1 device (which has the exact same radio core as nRF24L01+), with this source code, based on the nRFgo SDK v2.3 example "enhanced_shockburst" PRX:

devzone.nordicsemi.com/.../main.c

The RPD bit successfully detects the energy and I observe that the LEDs while in RX mode.

Kind regards,

Håkon

RE: CARRIERs SCAN PROCEDURE With nRF24L01+

LPO — Wed, 29 Aug 2018 17:55:59 GMT

Thanks Hakon for your support,

I had probed keeping the nrf24L01+ continuously in RX mode and reading the RPD in loop.
I had probed after CE=1 10uS to 5 mS, latchind CE to 0-1 keeping the nrf24L01+ continuously in RX mode and reading the RPD in loop.
I had probed after CE=1 10uS to 5 mS, latchind CE to 0-1-0 keeping the nrf24L01+ stamby-1 mode and reading the RPD in loop.

All time the register 09' is 00' (Bit0=0 of RPD)

RX an TX at 20 cm of distance with carrier receiving correcty in spectrum analycer.

Other question is what mean "a receive period", what time is this ?
And they are others conditions ?

The draw is 15 mA when in RX mode.

Thanks,
LPO

RE: CARRIERs SCAN PROCEDURE With nRF24L01+

Håkon Alseth — Mon, 27 Aug 2018 12:15:00 GMT

Hi,

Did you try to keep the nRF24L01+ continuously in RX mode (no switching RF channel), then read out the RPD bit in a loop to see if it changes?

The nRF24L01+ shall draw approx. 12 mA when in RX mode.

Best regards,

Håkon

RE: CARRIERs SCAN PROCEDURE With nRF24L01+

LPO — Sat, 25 Aug 2018 11:51:42 GMT

Hi, I tested whit the module MIKROE-1305 whit understand genuine nRF24L01+ I think. And the results are similar.

The energy detect funtion mush be inproved on nRF24L01+ if too only carriers or other chanels of other equipement exist and want be detected. This improviment is important when is need search free chanels on noisy ambients. Meanwile the specification mush corrected at tested cases.

If some people had detected energy with this cip, please talk here.

Thanks,

LPO

RE: CARRIERs SCAN PROCEDURE With nRF24L01+

Håkon Alseth — Tue, 31 Jul 2018 07:43:35 GMT

Yes, you are correct. This bit shall detect energy, but then it will not hold the RPD bit high for a longer period (as it would if a address match is found)

Could you try to keep the RX on, and do not duty cycle (in 5 ms pattern), to see if this has any impact on the RPD bit read out?

RE: CARRIERs SCAN PROCEDURE With nRF24L01+

LPO — Mon, 30 Jul 2018 17:29:41 GMT

Hi,

" it is just that this bit is held for a given period if you are receiving a valid packet"

With the specification "If no packets are received the RPD is latched at the end of a receive period as a result of host MCU setting CE low or RX time out controlled by Enhanced ShockBurst" , is no need receiving a valid packet i think.

The spectrum analyzer indicate they are carrier, but the RPD Register continue to 00' (STATUS=0E' corect)

I can be rong, but i think the nRF24L01+ can leve send only carrier and detect only carrier, similar to one comunication OOK

Kind regards,

LPO

RE: CARRIERs SCAN PROCEDURE With nRF24L01+

Håkon Alseth — Mon, 30 Jul 2018 12:08:25 GMT

Hi,

The RPD bit shall be '1' if there is energy in the current receiving channel is > -64 dBm, it is just that this bit is held for a given period if you are receiving a valid packet.

You shall still be able to use this bit to detect energy from for instance bluetooth or wifi.

Have you checked the current consumption (or the carrier using a spectrum analyzer) of your transmitter to see if it is actually transmitting? It should be 11 to 12 mA.

Same with your receiver, does it show ~14 mA in RX mode?

Kind regards,

Håkon

RE: CARRIERs SCAN PROCEDURE With nRF24L01+

LPO — Sun, 29 Jul 2018 15:55:44 GMT

Hi,

Hakon thanks for your replay...

On Page 25 of 78 of nRF24L01+ Single Chip 2.4GHz Transceiver Product Specification v1.0

6.4 Received Power Detector measurements

Can see "If no packets are received the RPD is latched at the end of a receive period as a result of host MCU setting CE low", option necesary for me search of ocuped channels without modulation (only carriers or others diferents modulations).

In me case they are one bucle of 5mS between CE=1 and CE=0 on PRX mode

Mush be > Tstby2a +Tdelay_AGC=130us + 40us but very less of 5mS ?

Best regards,

LPO

RE: CARRIERs SCAN PROCEDURE With nRF24L01+

LPO — Fri, 27 Jul 2018 16:19:10 GMT

Hi,

tested With PLL_LOCK Set (bit4=1) at PTX

the register RPD continue Reset (bit0=0) at PRX. Carrier non detected

Best regards,

LPO

PS: The Transceiver is RF2401PRO of NICERF from China. This claim it adopt Nordic's RF chip nRF24L01+

RE: CARRIERs SCAN PROCEDURE With nRF24L01+

Håkon Alseth — Fri, 27 Jul 2018 08:26:16 GMT

Hi,

In order to output a unmodulated carrier, you need to also set the PLL_LOCK bit in register RF_SETUP.

This is to avoid it "drifting away" over time.

Could you try this and report back?

Best regards,

Håkon