MRF24J40 Datasheet, PDF (15/66 Pages) Microchip Technology – IEEE 802.15.4™ 2.4 GHz RF Transceiver

4.0 SERIAL PERIPHERAL
INTERFACE (SPI)
4.1 Overview
The MRF24J40 is designed to interface directly with
the Serial Peripheral Interface (SPI) port available on
many microcontrollers. The implementation used on
this device supports SPI mode 0,0 only. In addition, the
SPI port requires that SCK be Idle in a low state;
selectable clock polarity is not supported.
MRF24J40
Commands and data are sent to the device via the SDI
pin, with data being clocked in on the rising edge of
SCK. Data is driven out by the MRF24J40 on the SDO
line, on the falling edge of SCK. The CS pin must be
held low while any operation is performed and returned
high when finished.
The MRF24J40 accesses the short and long RAM
banks in a slightly different manner. The following
sections describe the required waveforms in order to
read and write from both short and long RAM
addresses.
FIGURE 4-1:
CS
SPI INPUT TIMING
SCK
SDI
SDO
MSb In
High-Impedance State
LSb In
FIGURE 4-2:
CS
SPI OUTPUT TIMING
SCK
SDO
SDI
MSb Out
Don’t Care
LSb Out
© 2006 Microchip Technology Inc.
Advance Information
DS39776A-page 13