NRF52811-QCAA-R7 datasheet(186/444 Pages) NORDIC

186 / 444 page

Peripherals

Before the RADIO is able to receive a packet, it must first ramp up in RX mode, see RXRU in Radio states on

page 184 and Receive sequence on page 186.

An RXRU ramp up sequence is initiated when the RXEN task is triggered. After the RADIO has successfully

ramped up it will generate the READY event indicating that a packet reception can be initiated. A packet

reception is initiated by triggering the START task. As illustrated in Radio states on page 184, the START

task can first be triggered after the RADIO has entered into the RXIDLE state.

The following figure shows a single packet reception where the CPU manually triggers the different tasks

needed to control the flow of the RADIO, i.e. no shortcuts are used. If shortcuts are not used, a certain

amount of delay caused by CPU execution is expected between READY and START, and between END and

DISABLE. The RADIO will be listening and possibly receiving undefined data, represented with an 'X', from

START and until a packet with valid preamble (P) is received.

RXRU

RXIDLE

S0 L S1

PAYLOAD

CRC

RXIDLE

RXDISABLE

’X’

Figure 66: Receive sequence

The following figure shows a slightly modified version of the receive sequence, where the RADIO is

configured to use shortcuts between READY and START, and between END and DISABLE, which means that

no delay is introduced.

RXRU

S0 L S1

PAYLOAD

CRC

RXDISABLE

’X’

Figure 67: Receive sequence using shortcuts to avoid delays

The RADIO is able to receive consecutive packets without having to disable and re-enable the RADIO

between packets, as illustrated in the figure below.

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NRF52811-QCAA-R7 Datasheet(PDF) 186 Page - Nordic Semiconductor