Mesh range, power and mode

RE: Mesh range, power and mode

Susheel Nuguru — Wed, 23 May 2018 13:52:57 GMT

it would mean that there is a bug in mesh code somewhere if my proposed patch works.

RE: Mesh range, power and mode

Damien Berger — Wed, 23 May 2018 13:36:24 GMT

I am using nRF52840 Rev1 sorry.
Yes i can try with this setting if you think it would work but i would be strange since it works with -40dBm, isn't it ?

RE: Mesh range, power and mode

Susheel Nuguru — Wed, 23 May 2018 13:32:04 GMT

There seems to be a lot of places where i see RADIO_POWER_NRF_0DBM is hardcoded into the tx_power setting.Just to make sure can you set the tx power in radio_config.c file radio_config_config() function and set directly NRF_RADIO->TXPOWER = RADIO_POWER_NRF_POS8DBM

I am still wondering which version of the chip you are using for nRF52840

RE: Mesh range, power and mode

Damien Berger — Wed, 23 May 2018 12:52:02 GMT

Thank you i did not realize that it was not part of the mesh spec.
I completely understand if you can't assist us on this point.

Regarding the +8dBm, i added the line " RADIO_POWER_NRF_POS8DBM = 0x08," in the typedef definition as i showed before. Then i changed the tx_power in this function in advertiser.c:

static inline void set_default_broadcast_configuration(broadcast_t * p_broadcast)
{
    p_broadcast->params.access_address = BEARER_ACCESS_ADDR_DEFAULT;
    p_broadcast->params.radio_config.payload_maxlen = RADIO_CONFIG_ADV_MAX_PAYLOAD_SIZE;
    p_broadcast->params.radio_config.radio_mode = RADIO_MODE_BLE_1MBIT;
    p_broadcast->params.radio_config.tx_power = RADIO_POWER_NRF_POS8DBM;
}

and in this funcion in scanner.c:

void scanner_init(bearer_event_flag_callback_t packet_process_cb)
{
    memset(&m_scanner, 0, sizeof(m_scanner));

    packet_buffer_init(&m_scanner.packet_buffer, m_scanner.packet_buffer_data, SCANNER_BUFFER_SIZE);
    scanner_config_reset();
    m_scanner.config.radio_config.tx_power = RADIO_POWER_NRF_POS8DBM;
    m_scanner.config.radio_config.payload_maxlen = RADIO_CONFIG_ADV_MAX_PAYLOAD_SIZE;
    m_scanner.timer_window_end.cb = scan_window_end;
    m_scanner.timer_window_start.cb = scan_window_start;
    m_scanner.state = SCANNER_STATE_IDLE;
    m_scanner.window_state = SCAN_WINDOW_STATE_ON;
    m_scanner.nrf_mesh_process_flag = bearer_event_flag_add(packet_process_cb);
}

That's all, and when i change this two lines with "RADIO_POWER_NRF_NEG40DBM" it clearly works since the range is reduced to something like 1 meter.

RE: Mesh range, power and mode

Susheel Nuguru — Wed, 23 May 2018 12:38:18 GMT

Hi Damien,

Do you know that LR is not part of the Mesh spec and if you use this feature in your product, you will not be able to qualify it ?

The thread where Hung Bui gave a solution is very experimental and is not intended to be used in final products.

There are many other conventions that the Mesh stack assumes and I am not sure if every aspect of long range is taken into account here.

Since using LR with Mesh is out of our offering for now, I would not be able to spend time to assist in that. But, i would like to know why changing TX power from 4dBm to 8dBm had no effect.

Can you attach part of your code where you are changing the tx power

RE: Mesh range, power and mode

Susheel Nuguru — Wed, 23 May 2018 09:48:55 GMT

That seems like a good spot to test long range with 8dBm. It kind of looks the same as the testing place I used to test long range here. But looking at your results it does not look that the radio has changed TX power. Can you be absolutely sure by sniffing the radio registers that the NRF_RADIO-> TXPOWER register is set to the right value. Because the below results cannot be correct with the correct configuration

nRF52832 / 1MB / +4dBm : ~420 m

nRF52840 / 1MB / +8dBm : ~420 m

nRF52840 / LR / +8dBm : ~422 m

Also, which nRF52840 Rev IC are you testing with?

There is one thing I need to check regarding adding range delays to the mesh code for long range. I will check this an come back to you soon.

RE: Mesh range, power and mode

Damien Berger — Wed, 23 May 2018 08:34:03 GMT

I was only using two devices during each test, environment is not radio noisy, as you can see in the following picture, it is quite clear:

RE: Mesh range, power and mode

Susheel Nuguru — Wed, 23 May 2018 08:28:37 GMT

How are you testing this. Is the devices under test surrounded by many other devices. I mean to ask if the environment is very radio noisy? That could affect the range as there could be a lot of packet collisions in air causing corruption and hence lot of packet drops.

RE: Mesh range, power and mode

Damien Berger — Wed, 23 May 2018 08:16:58 GMT

I used The SDK for Mesh V2.0.1 which use S140 V6.0.0 (for nRF52840) :

http://infocenter.nordicsemi.com/index.jsp?topic=%2Fcom.nordic.infocenter.meshsdk.v2.0.1%2Findex.html&cp=4_1_0

RE: Mesh range, power and mode

Susheel Nuguru — Wed, 23 May 2018 08:01:53 GMT

Hi Damien,

Which softdevice version does the Mesh SDK use?

The long range feature was tested to work well on S140v6.0.0. I am not sure about the versions before. Also the change in radio tx power should very much influence the range.

RE: Mesh range, power and mode

Damien Berger — Tue, 22 May 2018 10:50:08 GMT

Does anyone have an idea about my case ?