SAM4L Datasheet, PDF (740/1185 Pages) ATMEL Corporation – ATSAM ARM-based Flash MCU

28.5 Application Block Diagram
Figure 28-2. Application Block Diagram
Host with
TWI
Interface
TWD
TWCK
Atmel TWI
serial EEPROM
Slave 1
I²C RTC
Slave 2
Rp: Pull up value as given by the I²C Standard
28.6 I/O Lines Description
Table 28-4.
Pin Name
TWD
TWCK
I/O Lines Description
Pin Description
Two-wire Serial Data
Two-wire Serial Clock
ATSAM4L4/L2
VDD
Rp
Rp
I²C LCD
controller
Slave 3
I²C temp.
sensor
Slave 4
Type
Input/Output
Input/Output
28.7 Product Dependencies
In order to use this module, other parts of the system must be configured correctly, as described
below.
28.7.1 I/O Lines
TWD and TWCK are bidirectional lines, connected to a positive supply voltage via a current
source or pull-up resistor (see Figure 28-5 on page 742). 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.
TWD and TWCK pins may be multiplexed with I/O Controller lines. To enable the TWIS, the
user must perform the following steps:
• Program the I/O Controller to:
– Dedicate TWD, TWCKas peripheral lines.
– Define TWD, TWCKas open-drain.
28.7.2
Power Management
If the CPU enters a sleep mode that disables clocks used by the TWIS, the TWIS will stop func-
tioning and resume operation after the system wakes up from sleep mode. The TWIS is able to
wake the system from sleep mode upon address match, see Section 28.8.9 on page 749.
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