Schematic for Arduino Force Units Connection Shield: An I2C...

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For Shielded RJ45 connector, is it better to connect SH-1 and SH-2 to ground or ...

suckatpcbb

@copilot Is it ok for me to assume that pin1 and pin2 are the same twisted pair, Pin3 and Pin4 are the same twisted pair, etc?

copilot

It's generally a reasonable assumption that pairs of adjacent pins on RJ-45 connectors correspond to the same twisted pair, particularly when following standard Ethernet wiring schemes such as T568A or T568B. The typically used pinout for Ethernet cables, which would use an RJ-45 connector like the RJHSE-5380, is as follows:

Pair 1: Pins 1 and 2
Pair 2: Pins 3 and 6
Pair 3: Pins 4 and 5
Pair 4: Pins 7 and 8

Based on this standard pinout, your assumption would not always hold true as per the T568A and T568B standards, because the pairs are not simply adjacent pins except for the first pair (Pins 1 and 2). Here's the standard mapping for clarity:

T568A

Pair 1: Pins 4 and 5 (Blue)
Pair 2: Pins 3 and 6 (Green)
Pair 3: Pins 1 and 2 (Orange)
Pair 4: Pins 7 and 8 (Brown)

T568B

Pair 1: Pins 4 and 5 (Blue)
Pair 2: Pins 1 and 2 (Orange)
Pair 3: Pins 3 and 6 (Green)
Pair 4: Pins 7 and 8 (Brown)

If you're following standard wiring, you'll need to check the specific Ethernet wiring scheme you intend to use.

For your project, the assignments for the pins on your RJHSE-5380 are as follows:

J5:1 and J5:2: First twisted pair (usually TX+ and TX-).
J5:3 and J5:5: Second twisted pair (usually RX+ and RX-).
J5:4 and J5:5
J5:7 and J5:8

In summary, Pins 1 and 2 form a pair; Pins 3 and 6 form a pair; Pins 4 and 5 form a pair, and Pins 7 and 8 form a pair.

Always refer to your specific component's datasheet or wiring standard for the most accurate information.

suckatpcbb

@copilot For Shielded RJ45 connector, is it better to connect SH-1 and SH-2 to ground or just one of them is enough?

copilot

For a shielded RJ45 connector like the RJHSE-5380, it is generally recommended to connect the shield pins (SH-1 and SH-2) to ground. The purpose of the shield is to protect against electromagnetic interference (EMI) and ensure proper grounding improves the effectiveness of the shielding. Here’s a breakdown of the connections:

Connect both SH-1 and SH-2 to ground: This ensures that the shield is adequately grounded and provides better EMI protection. Grounding both shield pins helps to minimize any potential voltage differences that could cause interference.

To summarize, you should:

Connect $J5:Shield \, (Pin \, 1)$ and $J5:Shield \, (Pin \, 2)$ to GND.

Would you like to make these connections in your design?

I know that i2c is not meant to be used on long distance application. However, i...

suckatpcbb

@copilot what's the resistance of the i2c pull-up resistor on arduino mega?

copilot

The Arduino Mega 2560 typically uses two 10 kΩ pull-up resistors for the I2C lines (SDA and SCL). These resistors are connected to the 5V supply rail. If you need to adjust these values for specific applications or increased bus speed, you might consider different resistor values.

Would you like any further assistance with the Arduino Loadcell System Shield project?

suckatpcbb

@copilot I know that i2c is not meant to be used on long distance application. However, if I have to do it, is it better to put the scl and sda lines on the same rj45 twisted pair to reduce noise? of is it better to put them on separate twisted pair?

copilot

Using I2C over long distances can indeed be challenging due to its susceptibility to noise and signal degradation. However, here are some considerations to optimize performance:

Twisted Pair Configuration

Placing SCL and SDA on the Same Twisted Pair:
- Advantages:
  - Twisting the two signal lines together can help to cancel out some external electromagnetic interference due to the close proximity of the conductors.
- Disadvantages:
  - This configuration can potentially cause crosstalk between the SCL and SDA lines, which could degrade signal integrity and data reliability.
Placing SCL and SDA on Separate Twisted Pairs:
- Advantages:
  - Reduces the chance of crosstalk between the clock and data lines.
- Disadvantages:
  - Each pair will have a different level of interference cancellation, which might make one signal cleaner than the other, depending on the pairing and environmental noise.

Recommended Approach

Twisted Pair Configuration: Pair each signal line (SCL and SDA) with a ground line. This reduces crosstalk and improves signal integrity.
- Pair 1: SCL + GND
- Pair 2: SDA + GND

Practical Tips

Pull-Up Resistors:
- Use strong pull-up resistors on the SCL and SDA lines. Values around 1kΩ to 4.7kΩ are typical for shorter distances, but you may need to experiment with lower values (e.g., 330Ω) for longer distances to maintain signal integrity.
Shielding:
- Using shielded cable for the RJ45 can provide an additional layer of noise protection. Ensure the shield is grounded properly.
I2C Extenders:
- You can use I2C bus extenders or buffers that are specifically designed to extend the I2C communication distance and improve noise immunity. Components like the P82B96 can be very effective for this purpose.
Reduced Speed:
- Reduce the I2C bus speed. The standard 100 kHz or 400 kHz speeds may be too fast for long distances. Experiment with the slowest possible speed that meets your application requirements.

By pairing each signal with a ground, you can improve the noise immunity of your system while reducing crosstalk, which is a common issue when transmitting high-frequency signals over longer distances.

Load_Cell_4_DRDY

+5V

Load_Cell_4_SCL

Load_Cell_4_DRDY

RESET

+5V

Load_Cell_4_SDA

VIN

Load_Cell_5_DRDY

Load_Cell_2_DRDY

Capacitance

10u F

Resistance

+5V

Capacitance

10u F

+5V

Load_Cell_5_SCL

Load_Cell_3_DRDY

Load_Cell_5_SDA

Load_Cell_3_DRDY

+3V3

+5V

Load_Cell_6_DRDY

Resistance

Load_Cell_5_DRDY

Load_Cell_3_SCL

Load_Cell_1_DRDY

Capacitance

10u F

Capacitance

10u F

+5V

Load_Cell_3_SDA

Load_Cell_6_DRDY

+5V

J13

J12

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Overlapping Copper • 4

Des	Net	Des	Net
J13:MH6	GND	Trace d123	Net 5
Trace 0d1d	Net 19	J11:A7	None
J11:A3	None	Trace b38c	Net 16
J11:A7	None	Trace 86d4	Net 19

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	Designator	Ruleset
	Fab Shapes	Override rules for Fab Shapes
	Footprint	Override rule for Footprint
	＊｀REF｀＊	Override rule for ＊｀REF｀＊
	＊｀REF｀＊	Override rule for ＊｀REF｀＊
	＊｀REF｀＊	Override rule for ＊｀REF｀＊
	＊｀REF｀＊	Override rule for ＊｀REF｀＊
	＊｀REF｀＊	Override rule for ＊｀REF｀＊
	J＊＊	Override rule for J＊＊
	J＊＊	Override rule for J＊＊
	J＊＊	Override rule for J＊＊

Airwires • 1

	Designators	Net
	U1:SCL4, J13:A7	Net 22

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	Name
	Trace 7384

Protected Intrusions

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Manufacturing

Manufacturer Part Number • 10

	Designator	MPN
	C1	None
	C2	None
	C3	None
	C4	None
	J1	None
	J2	None
	J3	None
	J4	None
	R1	None
	R2	None

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Ground
A common return path for electric current. Commonly known as ground.
jharwinbarrozo
20.5M
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jharwinbarrozo
11.4M
Generic Resistor
A generic fixed resistor for rapid developing circuit topology. Save precious design time by seamlessly add more information to this part (value, footprint, etc.) as it becomes available. Standard resistor values: 1.0Ω 10Ω 100Ω 1.0kΩ 10kΩ 100kΩ 1.0MΩ 1.1Ω 11Ω 110Ω 1.1kΩ 11kΩ 110kΩ 1.1MΩ 1.2Ω 12Ω 120Ω 1.2kΩ 12kΩ 120kΩ 1.2MΩ 1.3Ω 13Ω 130Ω 1.3kΩ 13kΩ 130kΩ 1.3MΩ 1.5Ω 15Ω 150Ω 1.5kΩ 15kΩ 150kΩ 1.5MΩ 1.6Ω 16Ω 160Ω 1.6kΩ 16kΩ 160kΩ 1.6MΩ 1.8Ω 18Ω 180Ω 1.8KΩ 18kΩ 180kΩ 1.8MΩ 2.0Ω 20Ω 200Ω 2.0kΩ 20kΩ 200kΩ 2.0MΩ 2.2Ω 22Ω 220Ω 2.2kΩ 22kΩ 220kΩ 2.2MΩ 2.4Ω 24Ω 240Ω 2.4kΩ 24kΩ 240kΩ 2.4MΩ 2.7Ω 27Ω 270Ω 2.7kΩ 27kΩ 270kΩ 2.7MΩ 3.0Ω 30Ω 300Ω 3.0KΩ 30KΩ 300KΩ 3.0MΩ 3.3Ω 33Ω 330Ω 3.3kΩ 33kΩ 330kΩ 3.3MΩ 3.6Ω 36Ω 360Ω 3.6kΩ 36kΩ 360kΩ 3.6MΩ 3.9Ω 39Ω 390Ω 3.9kΩ 39kΩ 390kΩ 3.9MΩ 4.3Ω 43Ω 430Ω 4.3kΩ 43KΩ 430KΩ 4.3MΩ 4.7Ω 47Ω 470Ω 4.7kΩ 47kΩ 470kΩ 4.7MΩ 5.1Ω 51Ω 510Ω 5.1kΩ 51kΩ 510kΩ 5.1MΩ 5.6Ω 56Ω 560Ω 5.6kΩ 56kΩ 560kΩ 5.6MΩ 6.2Ω 62Ω 620Ω 6.2kΩ 62KΩ 620KΩ 6.2MΩ 6.8Ω 68Ω 680Ω 6.8kΩ 68kΩ 680kΩ 6.8MΩ 7.5Ω 75Ω 750Ω 7.5kΩ 75kΩ 750kΩ 7.5MΩ 8.2Ω 82Ω 820Ω 8.2kΩ 82kΩ 820kΩ 8.2MΩ 9.1Ω 91Ω 910Ω 9.1kΩ 91kΩ 910kΩ 9.1MΩ #generics #CommonPartsLibrary
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1.5M
Generic Inductor
A generic fixed inductor for rapid developing circuit topology. *You can now change the footprint and 3D model at the top level anytime you want. This is the power of #generics
jharwinbarrozo
15.1k
Terminal
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natarius
RMCF0805JT47K0
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1.2M
875105359001
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1.2M
CTL1206FYW1T
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jharwinbarrozo
1.1M

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Arduino Force Units Connection Shield

Controls

Properties

Availability & Pricing

Distributor		Qty 1
	LCSC	$2.95

Assets

Octopus

id=image-from-rawpixel-id-6750654-jpeg

3d Model

Arduino UNO.STEP

id=Arduino UNO 3D

Arduino UNO R3 shield - Shape.dxf

id=Arduino UNO R3 shield - Shape

Thumbnail

ForceUnitShield.PNG

id=ForceUnitShield

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