Rainbow Electronics AT86RF231 - Manual (Page 27)

27
8111A–AVR–05/08
AT86RF231
6.5 Sleep/Wake-up and Transmit Signal (SLP_TR)
Pin 11 (SLP_TR) is a multi-functional pin. Its function relates to the current state of the
AT86RF231 and is summarized in
Table 6-8 on page 27 . The radio transceiver states are
explained in detail Section 7. “Operating Modes” on page 33 .
In states PLL_ON and TX_ARET_ON, pin SLP_TR is used as trigger input to initiate a TX trans-
action. Here pin SLP_TR is sensitive on rising edge only.
After initiating a state change by a rising edge at pin SLP_TR in radio transceiver states
TRX_OFF, RX_ON or RX_AACK_ON, the radio transceiver remains in the new state as long as
the pin is logical high and returns to the preceding state with the falling edge.
SLEEP state
The SLEEP state is used when radio transceiver functionality is not required, and thus the
AT86RF231 can be powered down to reduce the overall power consumption.
A power-down scenario is shown in Figure 6-15 on page 28 . When the radio transceiver is in
TRX_OFF state the microcontroller forces the AT86RF231 to SLEEP by setting SLP_TR = H. If
pin 17 (CLKM) provides a clock to the microcontroller this clock is switched off after 35 clock
cycles. This enables a microcontroller in a synchronous system to complete its power-down rou-
tine and prevent deadlock situations. The AT86RF231 awakes when the microcontroller
releases pin SLP_TR. This concept provides the lowest possible power consumption.
The CLKM clock frequency settings for 250 kHz and 62.5 kHz are not intended to directly clock
the microcontroller. When using these clock rates, CLKM is turned off immediately when enter-
ing SLEEP state.
Table 6-8. SLP_TR Multi-functional Pin
Transceiver Status Function Transition Description
PLL_ON TX start Starts frame transmission
TX_ARET_ON TX start Starts TX_ARET transaction
TRX_OFF Sleep Takes the radio transceiver into SLEEP state, CLKM disabled
SLEEP Wakeup Takes the radio transceiver back into TRX_OFF state, level sensitive
RX_ON Disable CLKM Takes the radio transceiver into RX_ON_NOCLK state and disables CLKM
RX_ON_NOCLK Enable CLKM Takes the radio transceiver into RX_ON state and enables CLKM
RX_AACK_ON Disable CLKM
Takes the radio transceiver into RX_AACK_ON_NOCLK state and disables
CLKM
RX_AACK_ON_NOCLK Enable CLKM Takes the radio transceiver into RX_AACK_ON state and enables CLKM
L H
⇒
L H
⇒
L H
⇒
H L
⇒
L H
⇒
H L
⇒
L H
⇒
H L
⇒