MRF24J40_10 Datasheet, PDF (125/156 Pages) Microchip Technology – IEEE 802.15.4™ 2.4 GHz RF Transceiver

MRF24J40
3.15.2 IMMEDIATE SLEEP AND WAKE-UP
MODE
In the Immediate Sleep and Wake-up mode, the host
microcontroller places the MRF24J40 to Sleep and
wakes it up.
To enable the Immediate Wake-up mode, set the
IMMWAKE (0x22<7>) bit to ‘1’.
To place the MRF24J40 to Sleep immediately, perform
the following two steps:
1. Perform a Power Management Reset by setting
the RSTPWR (0x2A<2>) bit to ‘1’. The bit will be
automatically cleared to ‘0’ by hardware.
2. Put the MRF24J40 to Sleep immediately by set-
ting the SLPACK (0x35<7>) bit to ‘1’. The bit will
be automatically cleared to ‘0’ by hardware.
Wake-up can be performed in one of two methods:
1. Wake-up on WAKE pin 15. To enable the WAKE
pin, set the WAKEPAD (0x0D<5>) bit to ‘1’ and
set the WAKE pin polarity. Set the WAKEPOL
(0x0D<7>) bit to ‘1’ for active-high signal, or
clear to ‘0’ for active-low signal.
or
2. Wake-up on register. To wake up the MRF24J40
from Sleep via the SPI port, set the REGWAKE
(0x22<6>) bit to ‘1’ and then clear to ‘0’.
After wake-up, delay at least 2 ms to allow 20 MHz main
oscillator time to stabilize before transmitting or receiving.
Example 3-3 summarizes the steps to prepare the
MRF24J40 for wake-up on WAKE pin and placing to
Sleep.
EXAMPLE 3-3: IMMEDIATE SLEEP AND WAKE
The steps to prepare the MRF24J40 for immediate sleep and wake up on WAKE pin
Prepare WAKE pin:
1. WAKE pin = low
2. RXFLUSH (0x0D) = 0x60 – Enable WAKE pin and set polarity to active-high
3. WAKECON (0x22) = 0x80 – Enable Immediate Wake-up mode
Put to Sleep:
4. SOFTRST (0x2A) = 0x04 – Perform a Power Management Reset
5. SLPACK (0x35) = 0x80 – Put MRF24J40 to Sleep immediately
To Wake:
6. WAKE pin = high – Wake-up
7. RFCTL (0x36) = 0x04 - RF State Machine reset
8. RFCTL (0x36) = 0x00
9. Delay 2 ms to allow 20 MHz main oscillator time to stabilize before transmitting or receiving.
© 2010 Microchip Technology Inc.
Preliminary
DS39776C-page 125