TX power has strange relationship with overall power of chip

[Ziyao Zhou]

I designed a PCB with only the nRF52833 chip and antenna. I want to learn about the relationship between different TX power levels and the overall power consumption of the chip.

I am using a power profiler with a 1.8V supply and reading the average current via software.

During the tests, the TX RX position remains fixed. I obtained the following results:

Why is the received signal strength higher when TX power is 0 dBm compared to when TX power is 4 dBm? Why does the overall power consumption increase when the TX power is reduced to negative values? I look forward to your response.：）

[hmolesworth]

If you happened to be using an nRF52832 I'd agree as that part interprets +8dBm as some negative value (it has no +8 setting)

 NRF_RADIO->TXPOWER = 0x08; // +8dBm 11.35mA Radio Tx and CPU
 NRF_RADIO->TXPOWER = 0x04; // +4dBm 23.17mA Radio Tx and CPU
 NRF_RADIO->TXPOWER = 0x00; //  0dBm 17.25mA Radio Tx and CPU

Didn't try the nRF52833 ..

Oh I see, bug here using a negative array index:

int peripheral_tx_power_levels[] = {0,-40, -20, -16, -12, -8, -4, 0, 3, 4, 8};
static int peripheral_tx_level_index = -8;	

ret_code_t err_code = sd_ble_gap_tx_power_set(BLE_GAP_TX_POWER_ROLE_ADV, m_advertising.adv_handle, peripheral_tx_power_levels[peripheral_tx_level_index]);

[Ziyao Zhou]

Thank you so much for your help!