AT32UC3C1512C Automotive Atmel Corporation, AT32UC3C1512C Automotive Datasheet - Page 1234

• Manufacturer Part Number: AT32UC3C1512C Automotive
• Manufacturer: Atmel Corporation

39.6.6.9
39.6.7
Table 39-30. aWire Command Summary
9166C–AVR-08/11
COMMAND
0x01
0x02
0x03
0x04
0x05
0x06
aWire Command Summary
CRC Errors/NACK Response
JTAG_ID
MEMORY_SPEED_REQUEST
Instruction
AYA
STATUS_REQUEST
TUNE
CHIP_ERASE
Two instructions exist to access the SAB: MEMORY_WRITE and MEMORY_READ. These two
instructions write and read words, halfwords, and bytes from the SAB.
Busy Reporting
If the aWire master, during a MEMORY_WRITE or a MEMORY_READ command, transmit
another byte when the aWire is still busy sending the previous byte to the SAB, the AW will
respond with a MEMORY_READ_WRITE_STATUS error. See chapter
more details.
The aWire master should adjust its baudrate or delay between bytes when doing SAB accesses
to ensure that the SAB is not overwhelmed with data.
Error Reporting
If a write is performed on a non-existing memory location the SAB interface will respond with an
error. If this happens, all further writes in this command will not be performed and the error and
number of bytes written is reported in the MEMORY_READWRITE_STATUS message from the
AW after the write.
If a read is performed on a non-existing memory location, the SAB interface will respond with an
error. If this happens, the data bytes read after this event are not valid. The AW will include three
extra bytes at the end of the transfer to indicate if the transfer was successful, or in the case of
an error, how many valid bytes were received.
The AW will calculate a CRC value when receiving the command, length, and data fields of the
command packets. If this value differs from the value from the CRC field of the packet, the AW
will reply with a NACK response. Otherwise the command is carried out normally.
An unknown command will be replied with a NACK response.
In worst case a transmission error can happen in the length or command field of the packet. This
can lead to the aWire slave trying to receive a command with or without length (opposite of what
the master intended) or receive an incorrect number of bytes. The aWire slave will then either
wait for more data when the master has finished or already have transmitted the NACK
response in congestion with the master. The master can implement a timeout on every com-
mand and reset the slave if no response is returned after the timeout period has ended.
The implemented aWire commands are shown in the table below. The responses from the AW
are listed in
Section
39.6.8.
Description
“Are you alive”.
Asks AW to return the JTAG IDCODE.
Request a status message from the AW.
Tell the AW to report the current baud rate.
Reports the speed difference between the aWire control and the SAB clock
domains.
Erases the flash and all volatile memories.
AT32UC3C
Section 39.6.8.5
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