Product Specs

23 RADIO — 2.4 GHz Radio
Page
209
State Description
RXDISABLE The radio is disabling the receiver
The status of the CRC check can be read from the CRCSTATUS register after a packet has been received.
23.7 Radio states
The RADIO can enter a number of states.
The RADIO can enter the states described the table below. An overview state diagram for the RADIO is
illustrated in Figure 34: Radio states on page 209. This figure shows how the tasks and events relate to
the RADIO's operation. The RADIO does not prevent a task from being triggered from the wrong state. If a
task is triggered from the wrong state, for example if the RXEN task is triggered from the RXDISABLE state,
this may lead to incorrect behaviour. As illustrated in Figure 34: Radio states on page 209, the PAYLOAD
event is always generated even if the payload is zero.
Table 39: RADIO state diagram
DISABLED No operations are going on inside the radio and the power consumption is at a minimum
RXRU The radio is ramping up and preparing for reception
RXIDLE The radio is ready for reception to start
RX Reception has been started and the addresses enabled in the RXADDRESSES register are being monitored
TXRU The radio is ramping up and preparing for transmission
TX The radio is transmitting a packet
TXDISABLE The radio is disabling the transmitter
DISABLE
Address sent / ADDRESS
START
TXDISABLE
TXRU TXIDLE TX
Ramp-up
/ DISABLED
TXEN
complete
/ READY
STOP
Packet sent / END
Payload sent [payload length >=0]
/ PAYLOAD
DISABLED
/ DISABLED
RXEN
Ramp-up
complete
/ READY
Packet received / END
Address received [Address match]
/ ADDRESS
START
RXDISABLE RXRU RXIDLE RX
DISABLE
STOP
Payload received [payload length >=0]
/ PAYLOAD
Figure 34: Radio states
23.8 Transmit sequence
Before the RADIO is able to transmit a packet, it must first ramp-up in TX mode.
See TXRU in Figure 34: Radio states on page 209 and Figure 35: Transmit sequence on page 210.
A TXRU ramp-up sequence is initiated when the TXEN task is triggered. After the radio has successfully
ramped up it will generate the READY event indicating that a packet transmission can be initiate. A packet
transmission is initiated by triggering the START task. As illustrated in Figure 34: Radio states on page 209
the START task can first be triggered after the RADIO has entered into the TXIDLE state.
Figure 35: Transmit sequence on page 210 illustrates a single packet transmission 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. As illustrated in Figure 35: Transmit sequence on page 210
TXIDLE The radio is ready for transmission to start