Silicon Laboratories EFR32xG21 Wireless Gecko Reference Manual page 571

When several interactions are possible from a set of pending commands, the interaction with the highest priority, i.e., the interaction
closest to the top of Table 21.2 I2C Interactions in Prioritized Order on page 570
Pending commands can be cleared by setting the CLEARPC command bit in I2C_CMD.
21.3.8.3 Automatic ACK Interaction
When receiving addresses and data, an ACK command in I2C_CMD is normally required after each received byte. When AUTOACK is
set in I2C_CTRL, an ACK is always pending, and the ACK-pending bit PACK in I2C_STATUS is thus always set, even after an ACK
has been consumed. This is used when data is picked using I2C_RXDOUBLE and can also be used with I2C_RXDATA in order to
reduce the amount of software interaction required during a transfer.
21.3.8.4 Reset State
After a reset, the state of the I
2
entire MCU, the I C-bus is assumed to be busy when coming out of a reset, and the BUSY flag in I2C_STATUS is thus set. To be able
to carry through master operations on the I
The bus goes idle when a STOP condition is detected on the bus, but on buses with little activity, the time before the I
tects that the bus is idle can be significant. There are two ways of assuring that the I
• Use the ABORT command in I2C_CMD. When the ABORT command is issued, the I
2
I C module can then initiate master operations.
• Use the Bus Idle Timeout. When SCL has been high for a long period of time, it is very likely that the bus is idle. Set BITO in
I2C_CTRL to an appropriate timeout period and set GIBITO in I2C_CTRL. If activity has not been detected on the bus within the
timeout period, the bus is then automatically assumed idle, and master operations can be initiated.
Note: If operating in slave mode, the above approach is not necessary.
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2
C-bus is unknown. To avoid interrupting transfers on the I
2
C-bus, the bus must be idle.
I2C - Inter-Integrated Circuit Interface
is applied to the bus.
2
C-bus after a reset of the I
2
C module gets out of the busy state.
2
C module is instructed that the bus is idle. The
Reference Manual
2
C module or the
2
C module de-
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