476
32072H–AVR32–10/2012
AT32UC3A3
23.5
Application Block Diagram
Figure 23-2. Application Block Diagram
23.6
I/O Lines Description
23.7
Product Dependencies
In order to use this module, other parts of the system must be configured correctly, as described
below.
23.7.1
I/O Lines
TWD and TWCK are bidirectional lines, connected to a positive supply voltage via a current
source or pull-up resistor (see
). When the bus is free, both lines are
high. The output stages of devices connected to the bus must have an open-drain or open-col-
lector to perform the wired-AND function.
TWALM is used to implement the optional SMBus SMBALERT signal.
The TWALM, TWD, and TWCK pins may be multiplexed with I/O Controller lines. To enable the
TWIM, the user must perform the following steps:
• Program the I/O Controller to:
– Dedicate TWD, TWCK, and optionally TWALM as peripheral lines.
– Define TWD, TWCK, and optionally TWALM as open-drain.
23.7.2
Power Management
If the CPU enters a sleep mode that disables clocks used by the TWIM, the TWIM will stop func-
tioning and resume operation after the system wakes up from sleep mode.
TWI
Master
TWD
TWCK
Atmel TWI
serial EEPROM
I
2
C RTC
I
2
C LCD
controller
I
2
C temp
sensor
Slave 2
Slave 3
Slave 4
VDD
Rp: pull-up value as given by the I2C Standard
TWALM
Slave 1
Rp
Rp
Rp
Table 23-4.
I/O Lines Description
Pin Name
Pin Description
Type
TWD
Two-wire Serial Data
Input/Output
TWCK
Two-wire Serial Clock
Input/Output
TWALM
SMBus SMBALERT
Input/Output
Содержание AT32UC3A3128
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