Chat
Welcome to Flux
Treat Flux like your intern. Tell it what you'd like to build and it'll get to work. You can also ask it questions, brainstorm ideas, and teach it your preferences. Learn More
Explain project
Write a project description
Find schematic issues
Create a test plan
Simulate a circuit
Prepare for Manufacturing
Component Selection Workflow
New Subsystem Wizard
Ready.
recoment pull up resistor gor gpb0 and gpb1
@copilot recoment pull up resistor gor gpb0 and gpb1
1y
For implementing pull-up resistors on GPB0 and GPB1 of the MCP23017 IO expander, I recommend using 10kΩ resistors based on common practice for I2C and similar communication lines, ensuring a low enough current to save power but high enough to ensure signal integrity.
Given the components and nets in your project, here's how you can add and connect the pull-up resistors:
-
Add two 10kΩ resistors (let's designate them as R2 and R3).
-
Connect R2 and R3 to a positive power supply voltage. In your schematic, you should connect them to the net attached to the VDD pin of the MCP23017. This connection ensures the pull-up functionality:
- Connect R2:1 to U3:VDD (Pin 9).
- Connect R3:1 to U3:VDD (Pin 9).
-
Connect the other ends of R2 and R3 to GPB0 and GPB1 respectively, enabling them to pull these lines to a high state when not actively driven low:
- Connect R2:2 to U3:GPB0 (Pin 1).
- Connect R3:2 to U3:GPB1 (Pin 2).
These connections ensure that GPB0 and GPB1 are normally pulled to a high logic level, which is a common requirement for interface lines to prevent noise from causing spurious signals when these lines are not actively driven by any device. Remember, it's good practice to closely place these pull-up resistors to the U3 (MCP23017-E/SS) on your PCB for better signal integrity.
1y
will I able to drive gp line to low like this ?
1y
Yes, you will be able to drive the GPB0 and GPB1 lines to low even with the pull-up resistors (R2 and R3) connected as recommended. Here is why:
The purpose of the pull-up resistors is to ensure that the GPB0 and GPB1 lines are at a known high voltage level when not actively driven by any device. This is especially useful in bus systems like I2C, where devices may have open-drain or open-collector outputs, meaning they can only pull a line low and not drive it high. The pull-up resistor enables the line to return to a high state when no device is pulling it low.
When the MCP23017 wants to drive either of these lines to a low state, it actively connects the line to ground (or a low voltage level) internally. The ability of the IO expander to sink current is sufficient to overcome the weak pull-up provided by the resistor, thus pulling the line to a low voltage level.
The value of the pull-up resistors (10 kΩ in this case) is a compromise between being large enough to limit the current and conserve power when a line is driven low, and being small enough to ensure a quick transition back to high when no longer being driven low. A 10kΩ resistor will consume I=V/R=5 V/10kΩ=0.5 mA when the line is driven to a low state, assuming a +5V supply voltage for simplicity. This current level is generally well within the capability of GPIO pins of typical microcontrollers and ICs like the MCP23017 to sink.
Therefore, even with the pull-up resistors connected to GPB0 and GPB1, you can drive these lines to a low state as needed for your application.
1y
Someone is typing...
7
is this ok to connect all the grounds to common ground
@copilot is this ok to connect all the grounds to common ground
1y
Connecting all the ground pins to a common ground in your project is not only okay but usually necessary to ensure a stable reference point for all components in the circuit. This common ground approach helps to avoid ground loops and potential differences between various parts of your circuit, which could introduce noise or improper operation of the components.
In your project, you have multiple ground connections listed, including those for integrated circuits (ICs), headers, and other components. For proper operation, you should ensure that all these ground points are connected together to form a single, common ground point. This includes the ground connections for:
- QMspi0Selector: Pin 7 (GND)
- U3(IO expander MCP23017-E-SS): Pin 10 (VSS)
- All the designators that explicitly state a ground connection or a connection to GND/VSS.
By connecting these together, you ensure that your circuit will have a solid ground reference for all components, which is crucial for the correct functioning of digital circuits like the ones involved in your SPI communication and IO expansion tasks.
Here's a direct list of connections for common ground:
- Connect QMspi0Selector:7 (GND) to U3:10 (VSS), ChipSelect:7 (GND), J2:4 (Pin_4), J61:2 (Pin_2), and J62:2 (Pin_2).
- Connect all other ground pins mentioned in Net 842cb171def542359add19e64861ba2d to this common ground net as well.
These connections ensure all parts of your project have a shared ground reference, helping to minimize issues related to signal integrity and ensuring reliable operation of the entire circuit.
1y
Someone is typing...
5
can we leave ~RESET~ pin as open
@copilot can we leave RESET pin as open
1y
Leaving the $\sim\text{RESET}$ pin open on devices like the MCP23017-E/SS can lead to unpredictable behavior because an undefined reset state can cause the device to not function as intended. It's generally recommended to connect the $\sim\text{RESET}$ pin to a known logic level to ensure predictable initial conditions.
For the MCP23017-E/SS, specifically:
-
If you want the device to be in a ready state immediately upon power-up, connect the $\sim\text{RESET}$ pin (Pin 18) to VDD (logic high) through a pull-up resistor. A typical value might be 10k$\Omega$. This ensures that the device is not accidentally held in the reset state.
-
If your design includes a microcontroller (MCU) or another device that can control the $\sim\text{RESET}$ line, you may connect the $\sim\text{RESET}$ pin to an MCU GPIO pin. This allows for software control of the MCP23017-E/SS reset state, handy for reinitializing the device without having to power cycle your entire system.
Given the description of your project, if you do not have a specific requirement to control the $\sim\text{RESET}$ pin via software, I would recommend the first approach for simplicity and reliability.
So, the connection would be:
- Connect U3(IO expander MCP23017-E-SS):$\sim\text{RESET}$ to a pull-up resistor (e.g., 10k$\Omega$), and then connect this resistor to VDD.
Please make sure to review your entire design to ensure that this approach fits well with the rest of your system requirements.
1y
Someone is typing...
4
how to give pull dow to GPB0
@copilot how to give pull dow to GPB0
1y
To add a pull-down resistor to the GPIO pin GPB0 of the IO expander MCP23017−E/SS, you can use a typical resistor value such as 10kΩ.
Here's how you can make the connections:
- Connect one end of the resistor to GPB0 U3:1.
- Connect the other end of the resistor to the ground.
In the list format:
- Connect R4:1 to U3:GPB0
- Connect R4:2 to U3:VSS (Ground)
You'll need to add a new resistor (let's call it R4) to your component list, or you can reuse one of the existing 10k resistors if available.
Would you like to add the new resistor R4 to your schematic? If so, please confirm, and I can help you with the necessary steps in detail.
1y
Someone is typing...
8
6
how much capacitance do i need to use here for MCP23017 between vcc and GND
@copilot how much capacitance do i need to use here for MCP23017 between vcc and GND
1y
For decoupling the MCP23017 IC, it is common practice to use a 0.1 µF $100$ nF ceramic capacitor close to the VDD pin $pin 9$ and GND $pin 10$. This value provides a good balance between cost, availability, and effectiveness for bypassing high-frequency noise in the power supply. Therefore:
- Connect a 0.1 µF capacitor as close as possible between U3:VDD and U3:VSS.
This is a typical value used for decoupling in many digital IC applications, and it's generally recommended in datasheets for similar devices. However, if your circuit will operate in an environment with significant electrical noise or you have specific concerns about power supply stability, consider adding additional bulk capacitance $e.g., 10 µF electrolytic or tantalum capacitor$ near the MCP23017 to help smooth out lower frequency fluctuations.
Remember, the effectiveness of a decoupling capacitor also heavily depends on its placement. Keep it physically close to the pins it is meant to decouple, with minimal trace lengths, to ensure it can efficiently shunt away any high-frequency noise.
1y
what whould be the voltage rating for decopuling capacitor
1y
For the voltage rating of the decoupling capacitor used with the MCP23017, a good rule of thumb is to choose a capacitor with a voltage rating at least 1.5 to 2 times higher than the supply voltage. Assuming the MCP23017 is powered by a standard $5V$ supply, I recommend selecting a decoupling capacitor with a voltage rating of at least $10V$.
This higher voltage rating helps ensure the capacitor remains reliable over its lifespan, accounting for possible fluctuations in the supply voltage and ensuring the capacitor's dielectric strength is not approached too closely. Additionally, capacitors with higher voltage ratings often have better longevity and can handle higher transient spikes without degradation.
Summary:
- For the 0.1 µF ceramic capacitor used for decoupling at the MCP23017, choose a voltage rating of at least $10V$.
1y
supply voltage is 3.3v
1y
Given that the supply voltage for your project is $3.3V$, the recommendation for the voltage rating of the decoupling capacitor would be slightly adjusted. Following the same guideline of choosing a capacitor with a voltage rating at least 1.5 to 2 times the operating voltage to ensure reliability and accommodate any potential voltage spikes, a voltage rating of $6.3V$ or higher would be suitable. However, capacitors with a $10V$ rating are more commonly available and might provide a larger margin of safety and potentially longer life.
Therefore:
- For the $0.1\mu F$ decoupling capacitor used with the MCP23017 on a $3.3V$ supply, select a voltage rating of at least $6.3V$, but $10V$ is a commonly available and safer choice.
1y
Someone is typing...
2
R2
Resistance
10kΩ
U3(IO expander MCP23017-E-SS(SSOP))
R3
Resistance
10kΩ
R1
Resistance
10kΩ
Dediprog header
J3
J2
C1
Capacitance
0.1uF
J7
Reviews
- Wirelessly connects nets on schematic. Used to organize schematics and separate functional blocks. To wirelessly connect net portals, give them same designator. #portaljharwinbarrozo43.0M
- Wirelessly connects power nets on schematic. Identical to the net portal, but with a power symbol. Used to organize schematics and separate functional blocks. To wirelessly connect power net portals, give them the same designator. #portal #powerjharwinbarrozo11.4M
- A generic fixed resistor ideal for rapid circuit topology development. Its footprint automatically adapts based on the selected package case code—supporting 0402, 0603, 0805, 1203, and many other standard SMD packages, as well as axial horizontal and vertical configurations. Save precious design time by seamlessly add more information to this part (value, footprint, etc.) as it becomes available. Standard resistor values: 1.0 ohm, 10 ohm, 100 ohm, 1.0k ohm, 10k ohm, 100k ohm, 1.0M ohm 1.1 ohm, 11 ohm, 110 ohm, 1.1k ohm, 11k ohm, 110k ohm, 1.1M ohm 1.2 ohm, 12 ohm, 120 ohm, 1.2k ohm, 12k ohm, 120k ohm, 1.2M ohm 1.3 ohm, 13 ohm, 130 ohm, 1.3k ohm, 13k ohm, 130k ohm, 1.3M ohm 1.5 ohm, 15 ohm, 150 ohm, 1.5k ohm, 15k ohm, 150k ohm, 1.5M ohm 1.6 ohm, 16 ohm, 160 ohm, 1.6k ohm, 16k ohm, 160k ohm, 1.6M ohm 1.8 ohm, 18 ohm, 180 ohm, 1.8K ohm, 18k ohm, 180k ohm, 1.8M ohm 2.0 ohm, 20 ohm, 200 ohm, 2.0k ohm, 20k ohm, 200k ohm, 2.0M ohm 2.2 ohm, 22 ohm, 220 ohm, 2.2k ohm, 22k ohm, 220k ohm, 2.2M ohm 2.4 ohm, 24 ohm, 240 ohm, 2.4k ohm, 24k ohm, 240k ohm, 2.4M ohm 2.7 ohm, 27 ohm, 270 ohm, 2.7k ohm, 27k ohm, 270k ohm, 2.7M ohm 3.0 ohm, 30 ohm, 300 ohm, 3.0K ohm, 30K ohm, 300K ohm, 3.0M ohm 3.3 ohm, 33 ohm, 330 ohm, 3.3k ohm, 33k ohm, 330k ohm, 3.3M ohm 3.6 ohm, 36 ohm, 360 ohm, 3.6k ohm, 36k ohm, 360k ohm, 3.6M ohm 3.9 ohm, 39 ohm, 390 ohm, 3.9k ohm, 39k ohm, 390k ohm, 3.9M ohm 4.3 ohm, 43 ohm, 430 ohm, 4.3k ohm, 43K ohm, 430K ohm, 4.3M ohm 4.7 ohm, 47 ohm, 470 ohm, 4.7k ohm, 47k ohm, 470k ohm, 4.7M ohm 5.1 ohm, 51 ohm, 510 ohm, 5.1k ohm, 51k ohm, 510k ohm, 5.1M ohm 5.6 ohm, 56 ohm, 560 ohm, 5.6k ohm, 56k ohm, 560k ohm, 5.6M ohm 6.2 ohm, 62 ohm, 620 ohm, 6.2k ohm, 62K ohm, 620K ohm, 6.2M ohm 6.8 ohm, 68 ohm, 680 ohm, 6.8k ohm, 68k ohm, 680k ohm, 6.8M ohm 7.5 ohm, 75 ohm, 750 ohm, 7.5k ohm, 75k ohm, 750k ohm, 7.5M ohm 8.2 ohm, 82 ohm, 820 ohm, 8.2k ohm, 82k ohm, 820k ohm, 8.2M ohm 9.1 ohm, 91 ohm, 910 ohm, 9.1k ohm, 91k ohm, 910k ohm, 9.1M ohm #generics #CommonPartsLibraryjharwinbarrozo1.5M
- A generic fixed capacitor ideal for rapid circuit topology development. You can choose between polarized and non-polarized types, its symbol and the footprint will automatically adapt based on your selection. Supported options include standard SMD sizes for ceramic capacitors (e.g., 0402, 0603, 0805), SMD sizes for aluminum electrolytic capacitors, and through-hole footprints for polarized capacitors. Save precious design time by seamlessly add more information to this part (value, footprint, etc.) as it becomes available. Standard capacitor values: 1.0pF, 10pF, 100pF, 1000pF, 0.01uF, 0.1uF, 1.0uF, 10uF, 100uF, 1000uF, 10000uF 1.1pF, 11pF, 110pF, 1100pF 1.2pF, 12pF, 120pF, 1200pF 1.3pF, 13pF, 130pF, 1300pF 1.5pF, 15pF, 150pF, 1500pF, 0.015uF, 0.15uF, 1.5uF, 15uF, 150uF, 1500uF 1.6pF, 16pF, 160pF, 1600pF 1.8pF, 18pF, 180pF, 1800pF 2.0pF, 20pF, 200pF, 2000pF 2.2pF, 22pF, 220pF, 2200pF, 0.022uF, 0.22uF, 2.2uF, 22uF, 220uF, 2200uF 2.4pF, 24pF, 240pF, 2400pF 2.7pF, 27pF, 270pF, 2700pF 3.0pF, 30pF, 300pF, 3000pF 3.3pF, 33pF, 330pF, 3300pF, 0.033uF, 0.33uF, 3.3uF, 33uF, 330uF, 3300uF 3.6pF, 36pF, 360pF, 3600pF 3.9pF, 39pF, 390pF, 3900pF 4.3pF, 43pF, 430pF, 4300pF 4.7pF, 47pF, 470pF, 4700pF, 0.047uF, 0.47uF, 4.7uF, 47uF, 470uF, 4700uF 5.1pF, 51pF, 510pF, 5100pF 5.6pF, 56pF, 560pF, 5600pF 6.2pF, 62pF, 620pF, 6200pF 6.8pF, 68pF, 680pF, 6800pF, 0.068uF, 0.68uF, 6.8uF, 68uF, 680uF, 6800uF 7.5pF, 75pF, 750pF, 7500pF 8.2pF, 82pF, 820pF, 8200pF 9.1pF, 91pF, 910pF, 9100pF #generics #CommonPartsLibraryjharwinbarrozo1.5M
- A generic fixed inductor suitable for rapid circuit topology development. The footprint automatically adapts based on the selected package, supporting standard SMD sizes (e.g., 0402, 0603, 0805) as well as well-known inductor packages such as SDR1806, PA4320, SRN6028, and SRR1260. Standard inductor values: 1.0 nH, 10 nH, 100 nH, 1.0 µH, 10 µH, 100 µH, 1.0 mH 1.2 nH, 12 nH, 120 nH, 1.2 µH, 12 µH, 120 µH, 1.2 mH 1.5 nH, 15 nH, 150 nH, 1.5 µH, 15 µH, 150 µH, 1.5 mH 1.8 nH, 18 nH, 180 nH, 1.8 µH, 18 µH, 180 µH, 1.8 mH 2.2 nH, 22 nH, 220 nH, 2.2 µH, 22 µH, 220 µH, 2.2 mH 2.7 nH, 27 nH, 270 nH, 2.7 µH, 27 µH, 270 µH, 2.7 mH 3.3 nH, 33 nH, 330 nH, 3.3 µH, 33 µH, 330 µH, 3.3 mH 3.9 nH, 39 nH, 390 nH, 3.9 µH, 39 µH, 390 µH, 3.9 mH 4.7 nH, 47 nH, 470 nH, 4.7 µH, 47 µH, 470 µH, 4.7 mH 5.6 nH, 56 nH, 560 nH, 5.6 µH, 56 µH, 560 µH, 5.6 mH 6.8 nH, 68 nH, 680 nH, 6.8 µH, 68 µH, 680 µH, 6.8 mH 8.2 nH, 82 nH, 820 nH, 8.2 µH, 82 µH, 820 µH, 8.2 mH #generics #CommonPartsLibraryjharwinbarrozo15.7k
- An electrical connector acting as reusable interface to a conductor and creating a point where external circuits can be connected.Terminal
- 47 kOhms ±5% 0.125W, 1/8W Chip Resistor 0805 (2012 Metric) Automotive AEC-Q200 Thick Film #forLedBlinkjharwinbarrozo1.2M
- 10uF Capacitor Aluminum Polymer 20% 16V SMD 5x5.3mm #forLedBlink #commonpartslibrary #capacitor #aluminumpolymer #radialcanjharwinbarrozo1.2M
- Yellow 595nm LED Indication - Discrete 1.7V 1206 (3216 Metric) #forLedBlinkjharwinbarrozo1.1M
Welcome to your new project. Imagine what you can build here.
Properties
Properties describe core aspects of the project.
Pricing & Availability
Distributor | Qty 1 |
|---|---|
Digi-Key | $1.74–$2.09 |
LCSC | $1.56 |
Mouser | $2.39 |
Assets
Assets are files uploaded to this project which can be used in various ways.
Controls
Welcome 👋
Flux helps you build PCBs faster with an AI teammate!
Create your account to collaborate, stay updated, fork your own version, and get instant answers from our AI agent.
abhijithkota
copilot