MRF24XA_15 Datasheet, PDF (90/258 Pages) Microchip Technology – Low-Power, 2.4 GHz ISM-Band IEEE 802.15.4™ RF

MRF24XA
FIGURE 4-1:
MAC FUNCTIONAL BLOCK DIAGRAM
4.2 Operations Overview
4.2.1 TERMINOLOGY
Node denotes the wireless communication node that is
formed by a MRF24XA device and a host MCU. Device
denotes the MRF24XA device. Software/SW denotes
the software running in the Host MCU. The device does
not contain a processor core that runs software. Frame
and Packet are used interchangeably.
4.2.2 HOST INTERFACE
The host MCU controls the device over SPI (max. 10
MHz), whereas the device indicates task completion or
failure events, and frames received over the air by rais-
ing an interrupt. Most interrupt flags are masked, which
means that these are still set on the respective event,
but cannot activate the interrupt pin on the device. The
host services the interrupts through reading the inter-
rupt register. The interrupt bytes are self-cleared on
SPI-read. Using the convention, the “IF” suffix in mne-
monics refers to “Interrupt Flag”. For example, TXIF
and RXIF. For software troubleshooting, the host can
set the interrupt flags.
4.2.3 BUFFERS
The device has two frame buffers (128 bytes each).
SPI allows accessing each byte in the frame buffer at
its own address. As the default, the buffer starting at
address 0x200 is used for transmission (BUF1) and the
buffer starting at address 0x300 is used for reception
(BUF2).
4.2.4 OPERATING STATES
The Figure 4-3 chart describes the top-level state
machine of MRF24XA, including the valid state
transitions. Note that the register access can also
perform the other transitions, however these may result
in an unexpected behavior.
For more information on the MRF24XA Power modes
on power consumption in each state, refer to Table 2-1.
4.2.4.1 Description of Each State
• RADIO IN PIN RESET: MCU keeps nRST pin low.
Radio is in reset, functions are unavailable.
• POWER OFF: Voltage on 3V3 pin is 0V. Radio is
shut down.
DS70005023C-page 90
Preliminary
 2015 Microchip Technology Inc.