AT32UC3L-EK Atmel, AT32UC3L-EK Datasheet - Page 480

• Manufacturer Part Number: AT32UC3L-EK
• Description: KIT EVAL AVR32 UC3 MCU
• Manufacturer: Atmel
• Type: MCUr

Specifications of AT32UC3L-EK

• Contents: *
• Silicon Manufacturer: Atmel
• Core Architecture: AVR
• Core Sub-architecture: UC3L
• Kit Contents: Board
• Features: USB / Battery Powered, Board Controller / Bootloader
• Svhc: No SVHC (15-Dec-2010)
• Rohs Compliant: Yes
• Tool Type: Starter Kit
• Cpu Core: AVR 8
• Data Bus Width: 8 bit
• Processor Series: AT32
• Processor To Be Evaluated: AT32UC3L064
• Interface Type: USB, Capacitive Touch
• For Use With/related Products: *
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Figure 21-15. A Read Transfer with 10-bit Addressing
21.8.9
21.8.9.1
32099F–11/2010
S
1
SLAVE ADDRESS
1
SMBus Mode
1
1st 7 bits
Packet Error Checking
1
0
X
X
RW A1
0
SMBus mode is enabled and disabled by the SMEN and SMDIS bits in CR. SMBus mode
operation is similar to I²C operation with the following exceptions:
Each SMBus transfer can optionally end with a CRC byte, called the PEC byte. Writing
CMDR.PECEN to one enables automatic PEC handling in the current transfer. Transfers with
and without PEC can freely be intermixed in the same system, since some slaves may not
support PEC. The PEC LFSR is always updated on every bit transmitted or received, so that
PEC handling on combined transfers will be correct.
In master transmitter mode, the master calculates a PEC value and transmits it to the slave
after all data bytes have been transmitted. Upon reception of this PEC byte, the slave will com-
pare it to the PEC value it has computed itself. If the values match, the data was received
correctly, and the slave will return an ACK to the master. If the PEC values differ, data was
corrupted, and the slave will return a NACK value. The DNAK bit in SR reflects the state of the
last received ACK/NACK value. Some slaves may not be able to check the received PEC in
time to return a NACK if an error occurred. In this case, the slave should always return an ACK
after the PEC byte, and some other mechanism must be implemented to verify that the trans-
mission was received correctly.
In master receiver mode, the slave calculates a PEC value and transmits it to the master after
all data bytes have been transmitted. Upon reception of this PEC byte, the master will com-
pare it to the PEC value it has computed itself. If the values match, the data was received
correctly. If the PEC values differ, data was corrupted, and the PECERR bit in SR is set. In
master receiver mode, the PEC byte is always followed by a NACK transmitted by the master,
since it is the last byte in the transfer.
The PEC byte is automatically inserted in a master transmitter transmission if PEC is enabled
when NBYTES reaches zero. The PEC byte is identified in a master receiver transmission if
PEC is enabled when NBYTES reaches zero. NBYTES must therefore be set to the total num-
ber of data bytes in the transmission, including the PEC byte.
1. Program CMDR with TENBIT=1, REPSAME=0, READ=0, START=1, STOP=0,
2. Program NCMDR with TENBIT=1, REPSAME=1, READ=1, START=1, STOP=1 and
• Only 7-bit addressing can be used.
• The SMBus standard describes a set of timeout values to ensure progress and throughput
• Transmissions can optionally include a CRC byte, called Packet Error Check (PEC).
• A dedicated bus line, SMBALERT, allows a slave to get a master’s attention.
• A set of addresses have been reserved for protocol handling, such as Alert Response
on the bus. These timeout values must be programmed into SMBTR.
Address (ARA) and Host Header (HH) Address.
NBYTES=0 and the desired address.
the desired address and NBYTES value.
SLAVE ADDRESS
2nd byte
A2
Sr
1
SLAVE ADDRESS
1
1
1st 7 bits
1
0
X
X
AT32UC3L016/32/64
RW A3
1
DATA
A
DATA
A
P
480