ATmega1284PR231 Atmel Corporation, ATmega1284PR231 Datasheet - Page 79

• Manufacturer Part Number: ATmega1284PR231
• Manufacturer: Atmel Corporation

Specifications of ATmega1284PR231

• Flash (kbytes): 128 Kbytes
• Max. Operating Frequency: 20 MHz
• Max I/o Pins: 32
• Spi: 3
• Twi (i2c): 1
• Uart: 2
• Adc Channels: 8
• Adc Resolution (bits): 10
• Adc Speed (ksps): 15
• Analog Comparators: 1
• Crypto Engine: AES
• Sram (kbytes): 16
• Eeprom (bytes): 4096
• Operating Voltage (vcc): 1.8 to 3.6
• Timers: 3
• Frequency Band: 2.4 GHz
• Max Data Rate (mb/s): 2
• Antenna Diversity: Yes
• External Pa Control: Yes
• Power Output (dbm): 3
• Receiver Sensitivity (dbm): -101
• Receive Current Consumption (ma): 13.2
• Transmit Current Consumption (ma): 14.4
• Link Budget (dbm): 104

8. Functional Description
8.1
Figure 8-1.
8.1.1
8.1.1.1
8.1.1.2
8.1.1.3
8111C–MCU Wireless–09/09
Introduction - IEEE 802.15.4 - 2006 Frame Format
PHY Protocol Layer Data Unit (PPDU)
8.1.1.1 Synchronization Header (SHR)
PHY Payload (PHY Service Data Unit, PSDU)
PHY Header (PHR)
IEEE 802.15.4 Frame Format - PHY-Layer Frame Structure (PPDU)
Preamble Sequence
Synchronization Header (SHR)
5 octets
Figure 8-1 on page 79
defined by IEEE 802.15.4.
access control (MAC) layer.
The SHR consists of a four-octet preamble field (all zero), followed by a single byte start-of-
frame delimiter (SFD) which has the predefined value 0xA7. During transmit, the SHR is auto-
matically generated by the AT86RF231, thus the Frame Buffer shall contain PHR and PSDU
only.
The transmission of the SHR requires 160 µs (10 symbols). As the SPI data rate is normally
higher than the over-air data rate, this allows the microcontroller to initiate a transmission without
having transferred the full frame data already. Instead it is possible to subsequently write the
frame content.
During frame reception, the SHR is used for synchronization purposes. The matching SFD
determines the beginning of the PHR and the following PSDU payload data.
The PHY header is a single octet following the SHR. The least significant 7 bits denote the frame
length of the following PSDU, while the most significant bit of that octet is reserved, and shall be
set to 0 for IEEE 802.15.4 compliant frames.
On receive the PHR is returned as the first octet during Frame Buffer read access. Even though
the standard only defines frame lengths ≤127 bytes, AT86RF231 is able to transmit and receive
frame length values >127. For IEEE 802.15.4 compliant operation bit 7 has to be masked by
SW. The reception of a valid PHR is signaled by an interrupt IRQ_2 (RX_START).
On transmit the PHR is to be supplied by the microcontroller during Frame Buffer write access
as the first octet.
The PSDU has a variable length between 0 and aMaxPHYPacketSize (127, maximum PSDU
size in octets) whereas the last two octets are used for the Frame Check Sequence (FCS). The
length of the PSDU is signaled by the frame length field (PHR), refer to
The PSDU contains the MAC Protocol Layer Data Unit (MPDU).
SFD
provides an overview of the physical layer (PHY) frame structure as
PHY Protocol Data Unit (PPDU)
Frame Length
1 octet
(PHR)
Figure 8-2 on page 80
shows the frame structure of the medium
MAC Protocol Data Unit (MPDU)
PHY Service Data Unit (PSDU)
max. 127 octets
PHY Payload
Table 8-1 on page
AT86RF231
80.
79