User Manual

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nRF24L01+ Product Specification
Appendix A - Enhanced ShockBurst™ - Configuration and communi-
cation example
Enhanced ShockBurst™ transmitting payload
1. Set the configuration bit PRIM_RX low.
2. When the application MCU has data to transmit, clock the address for the receiving node
(
TX_ADDR) and payload data (TX_PLD) into nRF24L01+ through the SPI. The width of TX-pay-
load is counted from the number of bytes written into the TX FIFO from the MCU.
TX_PLD must
be written continuously while holding
CSN low. TX_ADDR does not have to be rewritten if it is
unchanged from last transmit. If the PTX device shall receive acknowledge, configure data pipe 0
to receive the ACK packet. The RX address for data pipe 0 (
RX_ADDR_P0) must be equal to the
TX address (
TX_ADDR) in the PTX device. For the example in Figure 14. on page 41 perform the
following address settings for the TX5 device and the RX device:
TX5 device:
TX_ADDR = 0xB3B4B5B605
TX5 device:
RX_ADDR_P0 = 0xB3B4B5B605
RX device:
RX_ADDR_P5 = 0xB3B4B5B605
3. A high pulse on
CE starts the transmission. The minimum pulse width on CE is 10µs.
4. nRF24L01+ ShockBurst™:
X Radio is powered up.
X 16MHz internal clock is started.
X RF packet is completed (see the packet description).
X Data is transmitted at high speed (1Mbps or 2Mbps configured by MCU).
5. If auto acknowledgement is activated (
ENAA_P0=1) the radio goes into RX mode immediately,
unless the
NO_ACK bit is set in the received packet. If a valid packet is received in the valid
acknowledgement time window, the transmission is considered a success. The
TX_DS bit in the
STATUS register is set high and the payload is removed from TX FIFO. If a valid ACK packet is
not received in the specified time window, the payload is retransmitted (if auto retransmit is
enabled). If the auto retransmit counter (
ARC_CNT) exceeds the programmed maximum limit
(ARC), the
MAX_RT bit in the STATUS register is set high. The payload in TX FIFO is NOT
removed. The
IRQ pin is active when MAX_RT or TX_DS is high. To turn off the IRQ pin, reset the
interrupt source by writing to the
STATUS register (see Interrupt chapter). If no ACK packet is
received for a packet after the maximum number of retransmits, no further packets can be trans-
mitted before the
MAX_RT interrupt is cleared. The packet loss counter (PLOS_CNT) is incre-
mented at each
MAX_RT interrupt. That is, ARC_CNT counts the number of retransmits that were
required to get a single packet through.
PLOS_CNT counts the number of packets that did not get
through after the maximum number of retransmits.
6. nRF24L01+ goes into standby-I mode if
CE is low. Otherwise, next payload in TX FIFO is trans-
mitted. If TX FIFO is empty and
CE is still high, nRF24L01+ enters standby-II mode.
7. If nRF24L01+ is in standby-II mode, it goes to standby-I mode immediately if
CE is set low.