Atmel Evaluation Kit AT91SAM9M10-G45-EK AT91SAM9M10-G45-EK Data Sheet
Product codes
AT91SAM9M10-G45-EK
481
SAM9M10 [DATASHEET]
6355F–ATARM–12-Mar-13
defined pattern with a programmable length from 1 to 15 bit times. If the preamble length is set to 0, the preamble
waveform is not generated prior to any character. The preamble pattern is chosen among the following sequences:
ALL_ONE, ALL_ZERO, ONE_ZERO or ZERO_ONE, writing the field TX_PP in the US_MAN register, the field
TX_PL is used to configure the preamble length.
waveform is not generated prior to any character. The preamble pattern is chosen among the following sequences:
ALL_ONE, ALL_ZERO, ONE_ZERO or ZERO_ONE, writing the field TX_PP in the US_MAN register, the field
TX_PL is used to configure the preamble length.
flexibility, the encoding scheme can be configured using the TX_MPOL field in the US_MAN register. If the
TX_MPOL field is set to zero (default), a logic zero is encoded with a zero-to-one transition and a logic one is
encoded with a one-to-zero transition. If the TX_MPOL field is set to one, a logic one is encoded with a one-to-zero
transition and a logic zero is encoded with a zero-to-one transition.
TX_MPOL field is set to zero (default), a logic zero is encoded with a zero-to-one transition and a logic one is
encoded with a one-to-zero transition. If the TX_MPOL field is set to one, a logic one is encoded with a one-to-zero
transition and a logic zero is encoded with a zero-to-one transition.
Figure 31-9.
Preamble Patterns, Default Polarity Assumed
A start frame delimiter is to be configured using the ONEBIT field in the US_MR register. It consists of a user-
defined pattern that indicates the beginning of a valid data.
delimiter, also known as start bit, is one bit, (ONEBIT at 1), a logic zero is Manchester encoded and indicates that
a new character is being sent serially on the line. If the start frame delimiter is a synchronization pattern also
referred to as sync (ONEBIT at 0), a sequence of 3 bit times is sent serially on the line to indicate the start of a new
character. The sync waveform is in itself an invalid Manchester waveform as the transition occurs at the middle of
the second bit time. Two distinct sync patterns are used: the command sync and the data sync. The command
sync has a logic one level for one and a half bit times, then a transition to logic zero for the second one and a half
bit times. If the MODSYNC field in the US_MR register is set to 1, the next character is a command. If it is set to 0,
the next character is a data. When direct memory access is used, the MODSYNC field can be immediately updated
with a modified character located in memory. To enable this mode, VAR_SYNC field in US_MR register must be
set to 1. In this case, the MODSYNC field in US_MR is bypassed and the sync configuration is held in the TXSYNH
a new character is being sent serially on the line. If the start frame delimiter is a synchronization pattern also
referred to as sync (ONEBIT at 0), a sequence of 3 bit times is sent serially on the line to indicate the start of a new
character. The sync waveform is in itself an invalid Manchester waveform as the transition occurs at the middle of
the second bit time. Two distinct sync patterns are used: the command sync and the data sync. The command
sync has a logic one level for one and a half bit times, then a transition to logic zero for the second one and a half
bit times. If the MODSYNC field in the US_MR register is set to 1, the next character is a command. If it is set to 0,
the next character is a data. When direct memory access is used, the MODSYNC field can be immediately updated
with a modified character located in memory. To enable this mode, VAR_SYNC field in US_MR register must be
set to 1. In this case, the MODSYNC field in US_MR is bypassed and the sync configuration is held in the TXSYNH
in the US_THR register. The USART character format is modified and includes sync information.
Manchester
encoded
data
Txd
SFD
DATA
8 bit width "ALL_ONE" Preamble
Manchester
encoded
data
Txd
SFD
DATA
8 bit width "ALL_ZERO" Preamble
Manchester
encoded
data
Txd
SFD
DATA
8 bit width "ZERO_ONE" Preamble
Manchester
encoded
data
Txd
SFD
DATA
8 bit width "ONE_ZERO" Preamble