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nRF51822 ESB Rx and Tx mode enable and disable times

I have a custom board with the nRF51822 chip, the chip is set-up with the recommended (CFAC WLCSP schematic with low voltage mode) setup, excluding the external low frequency clock, according to the [nRF51822_PS v3.1].

In this product specification document it is written that the Radio Time between TXEN task and READY event for 2M data-rate is 132 us and 130 us for RXEN.

I measured the timing and indeed it is as specified in the document BUT that is only for the basic proprietary radio protocol. In the case of ESB protocol the timing I measured was around 379 us for the ESB Rx Mode (Between setting the mode to Rx and then calling the nrf_esb_enable, and getting the callback from the nrf_esb_is_enabled()).

This number even jumps to 603 us if I wait for the NRF_RADIO EVENTS_READY instead of the nrf_esb_is_enabled() !!

I want to know if those number are normal ?

also I want to know if nordic semiconductors have official numbers for the timing of switching-on and switching-off the ESB protocol in Tx or Rx mode for me to compare my timings with ?

  • Hi,

    The ESB library provided in our SDK is synchronous under-the-hood, which means that each operation is performed based on a "tick" (set by your nrf_esb_set_retransmit_delay() function), which can cause such delays. In addition, the ESB protocol is run in software, so for each packet, the cpu needs to parse and verify its content.

    We also have provided a micro-esb library, which is open source here: github.com/.../nrf51-micro-esb

    Using this protocol, you have more control over the radio protocol and you can enable/disable it much faster.

    Best regards, Håkon

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