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# Copyright (c) 2020-2023 Gerson Fernando Budke <nandojve@gmail.com>
# SPDX-License-Identifier: Apache-2.0
description: |
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.
compatible: "atmel,sam-i2c-twim"
include:
- name: i2c-controller.yaml
- name: pinctrl-device.yaml
properties:
reg:
required: true
interrupts:
required: true
clocks:
required: true
std-clk-slew-lim:
type: int
required: true
description: |
Slew limit of the TWCK output buffer. This should be adjusted with
std-clk-strength-low to fine tune the TWCK slope.
enum:
- 0
- 1
- 2
- 3
std-clk-strength-low:
type: string
required: true
description: |
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.
enum:
- "0.5"
- "1.0"
- "1.6"
- "3.1"
- "6.2"
- "9.3"
- "15.5"
- "21.8"
std-data-slew-lim:
type: int
required: true
description: |
Slew limit of the TWD output buffer. This should be adjusted with
std-data-strength-low to fine tune the TWD slope.
enum:
- 0
- 1
- 2
- 3
std-data-strength-low:
type: string
required: true
description: |
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.
enum:
- "0.5"
- "1.0"
- "1.6"
- "3.1"
- "6.2"
- "9.3"
- "15.5"
- "21.8"
hs-clk-slew-lim:
type: int
required: true
description: |
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.
enum:
- 0
- 1
- 2
- 3
hs-clk-strength-high:
type: string
required: true
description: |
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.
enum:
- "0.5"
- "1.0"
- "1.5"
- "3.0"
hs-clk-strength-low:
type: string
required: true
description: |
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.
enum:
- "0.5"
- "1.0"
- "1.6"
- "3.1"
- "6.2"
- "9.3"
- "15.5"
- "21.8"
hs-data-slew-lim:
type: int
required: true
description: |
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.
enum:
- 0
- 1
- 2
- 3
hs-data-strength-low:
type: string
description: |
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.
enum:
- "0.5"
- "1.0"
- "1.6"
- "3.1"
- "6.2"
- "9.3"
- "15.5"
- "21.8"
hs-master-code:
type: int
required: true
description: |
3-bit code to be prefixed with 0b00001 to form a unique
8-bit HS-mode master code (0000 1XXX)
enum:
- 0 # 000
- 1 # 001
- 2 # 010
- 3 # 011
- 4 # 100
- 5 # 101
- 6 # 110
- 7 # 111