atmel,sam-i2c-twim¶
Vendor: Atmel Corporation
Description¶
These nodes are “i2c” bus nodes.
Atmel SAM4L Family I2C (TWIM) node
The Atmel Two-wire Master Interface (TWIM) interconnects components on a
unique two-wire bus, made up of one clock line and one data line with speeds
of up to 3.4 Mbit/s, based on a byte-oriented transfer format. The TWIM is
always a bus master and can transfer sequential or single bytes. Multiple
master capability is supported. Arbitration of the bus is performed
internally and relinquishes the bus automatically if the bus arbitration is
lost.
When using speeds above standard mode, user may need adjust clock and data
lines slew and strength parameters. In general, slew 0 and minimal strength
is enougth for short buses and light loads. As reference, the below
is the lowest power configuration:
std-clk-slew-lim = <0>;
std-clk-strength-low = "0.5";
std-data-slew-lim = <0>;
std-data-strength-low = "0.5";
hs-clk-slew-lim = <0>;
hs-clk-strength-high = "0.5";
hs-clk-strength-low = "0.5";
hs-data-slew-lim = <0>;
hs-data-strength-low = "0.5";
For best performances, user can tune the slope curves using an osciloscope.
The tuning should be performed by groups defined <mode>-<line>. The prefix
std-<line> configures fast/fast-plus mode speeds and hs-<line> selects the
high speed mode. The tune should be performed for both clock and data lines
on both speed modes.
Properties¶
Node specific properties
Properties not inherited from the base binding file.
Name |
Type |
Details |
|---|---|---|
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peripheral ID
This property is required. |
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Slew limit of the TWCK output buffer. This should be adjusted with
std-clk-strength-low to fine tune the TWCK slope.
This property is required. Legal values: |
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Pull-down drive strength of the TWCK output buffer in fast/fast plus
mode. This should be adjusted to provide proper TWCK line fall time.
The value represents the port output current in mA when signal on
low level.
This property is required. Legal values: |
|
|
Slew limit of the TWD output buffer. This should be adjusted with
std-data-strength-low to fine tune the TWD slope.
This property is required. Legal values: |
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Pull-down drive strength of the TWD output buffer in fast/fast plus
mode. This should be adjusted to provide proper TWD line fall time.
The value represents the port output current in mA when signal on
low level.
This property is required. Legal values: |
|
|
Slew limit of the TWCK output buffer in high speed mode. This
should be adjusted with both hs-clk-strength-high and
hs-clk-strength-low to fine tune the TWCK slope.
This property is required. Legal values: |
|
|
Pull-up drive strength of the TWCK output buffer in high speed
mode. This should be adjusted to provide proper TWCK line rise time.
The value represents the port output current in mA when signal on
high level.
This property is required. Legal values: |
|
|
Pull-down drive strength of the TWCK output buffer in high speed
mode. This should be adjusted to provide proper TWCK line fall time.
The value represents the port output current in mA when signal on
low level.
This property is required. Legal values: |
|
|
Slew limit of the TWD output buffer in high speed mode. This
should be adjusted with hs-data-strength-low to fine tune the TWD
slope.
This property is required. Legal values: |
|
|
Pull-down drive strength of the TWD output buffer in high speed
mode. This should be adjusted to provide proper TWD line fall time.
The value represents the port output current in mA when signal on
low level.
Legal values: |
|
|
3-bit code to be prefixed with 0b00001 to form a unique
8-bit HS-mode master code (0000 1XXX)
This property is required. Legal values: |
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GPIO pin configuration for TWCK & TWD signals. We expect that
the phandles will reference pinctrl nodes. These nodes will
have a nodelabel that matches the Atmel SoC HAL defines and
be of the form p<port><pin><periph>_<inst>_<signal>.
For example the I2C on SAM4L would be
pinctrl-0 = <&pb0a_twi1_twd1 &pb1a_twi1_twck1>;
This property is required. |
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Initial clock frequency in Hz
|
Deprecated node specific properties
Deprecated properties not inherited from the base binding file.
(None)
Base properties
Properties inherited from the base binding file, which defines common properties that may be set on many nodes. Not all of these may apply to the “atmel,sam-i2c-twim” compatible.
Name |
Type |
Details |
|---|---|---|
|
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register space
This property is required. See Important properties for more information. |
|
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interrupts for device
This property is required. See Important properties for more information. |
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number of address cells in reg property
This property is required. Constant value: |
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number of size cells in reg property
This property is required. |
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Human readable string describing the device (used as device_get_binding() argument)
This property is required. See Important properties for more information. |
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indicates the operational status of a device
Legal values: See Important properties for more information. |
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compatible strings
This property is required. See Important properties for more information. |
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name of each register space
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extended interrupt specifier for device
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name of each interrupt
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phandle to interrupt controller node
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Clock gate information
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name of each clock
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DMA channels specifiers
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Provided names of DMA channel specifiers
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IO channels specifiers
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Provided names of IO channel specifiers
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Property to identify that a device can be used as wake up source.
When this property is provided a specific flag is set into the
device that tells the system that the device is capable of
wake up the system.
Wake up capable devices are disabled (interruptions will not wake up
the system) by default but they can be enabled at runtime if necessary.
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