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

Write I2C initialization code

Generate firmware skeleton

how many unique parts does this project have?

nico

@copilot how many unique parts does this project have?

copilot

The project has 11 unique parts. Here they are:

Generic Resistor (1kΩ, 22Ω, 65Ω)
Generic Capacitor (Non-Polarized)
Terminal
12 MHz Crystal Oscillator
USB-C Receptacle USB2.0
RP2040
LED_SMD
NPN Transistor
W25Q128JVSIQ
AMS1117-3.3
Generic Capacitor (Non-Polarized)

Please note that while some parts are of the same type (like the resistors and capacitors), they have different properties and thus are considered unique.

nico

How many SMT pads in total?

copilot

To calculate the total number of SMT pads, we need to count the number of pins on each SMT component in the design.

Here's the breakdown:

R1, R2, R3, R4 (Generic Resistor): 4 components x 2 pins = 8 pads
C1, C2 (Generic Capacitor): 2 components x 2 pins = 4 pads
Y1 (12 MHz Crystal Oscillator): 1 component x 2 pins = 2 pads
J1 (USB-C Receptacle USB2.0): 1 component x 14 pins = 14 pads
U1 (RP2040): 1 component x 49 pins = 49 pads
D1 (LED_SMD): 1 component x 2 pins = 2 pads
Q1 (NPN Transistor): 1 component x 3 pins = 3 pads
U3 (W25Q128JVSIQ): 1 component x 8 pins = 8 pads
U2 (AMS1117-3.3): 1 component x 4 pins = 4 pads

By adding these up, we find that there are a total of 94 SMT pads in this design.

why do I need these R1 and R2 resistors on the USB lines?

nico

@copilot why do I need these R1 and R2 resistors on the USB lines?

copilot

The resistors R1 and R2 on the USB data lines (D+ and D-) are known as "series termination resistors". They are used for impedance matching purposes.

In high-speed digital signaling, like USB communication which can reach up to 480 Mbps in USB 2.0, it's crucial to maintain signal integrity to ensure reliable data transmission.

Here are the main reasons for using them:

Impedance Matching: To prevent signal reflections that can cause data corruption, the impedance of the transmission line (USB cable) should be matched to the impedance of the driver and receiver. The resistors help match the impedance.
Signal Conditioning: The resistors can help to condition the signal by reducing signal overshoot and undershoot, which can also contribute to maintaining signal integrity.
ESD Protection: They can provide some level of electrostatic discharge (ESD) protection for the microcontroller's USB data line pins.

The value of these resistors is typically around 22 Ohms for USB 2.0 applications, which seems to be the case in your design with R1 and R2.

how do I provide more current to the LED?

nico

@copilot how do I provide more current to the LED?

copilot

The amount of current flowing through an LED is primarily determined by the resistor in series with it. In your case, the resistor R4 is in series with the LED D1. The current flow through the LED can be increased by reducing the resistance of R4.

The current through the LED is given by Ohm's Law:

[ I = \frac{V}{R} ]

Where:

I is the current,
V is the voltage across the resistor,
R is the resistance.

If you want to increase the current, you need to decrease the resistance R. However, please be aware that increasing the current will also increase the power dissipation in the LED, which can cause it to overheat if the current is too high.

Before making any changes, you should check the maximum forward current rating of your LED from its datasheet to ensure that the new current will not exceed this rating.

how do I connect this to the regulator and the rp2040?

nico

@copilot how do I connect this to the regulator and the rp2040?

copilot

To connect the USB-C receptacle (J1) to the AMS1117-3.3 voltage regulator (U2) and the RP2040 microcontroller (U1), follow these steps:

Connect VBUS from J1 to the VI pin of U2 to provide the input voltage to the regulator.
Connect GND pins from J1 to the GND pins of both U2 and U1 to provide a common ground reference.
Connect the VO pin of U2 to the IOVDD, DVDD, ADC_AVDD, and USB_VDD pins of U1 to supply the regulated 3.3V.
Connect the D+ and D- pins of J1 to the USB_DP and USB_DM pins of U1, respectively, for USB communication.
Connect the CC1 and CC2 pins of J1 through 5.1kΩ resistors to the GND to set the USB-C receptacle as a downstream-facing port (DFP). This will allow the device to be recognized as a USB host or device, depending on the design requirements.

Here's a summary of the connections:

J1 (VBUS) -> U2 (VI)
J1 (GND) -> U2 (GND) -> U1 (GND)
U2 (VO) -> U1 (IOVDD, DVDD, ADC_AVDD, USB_VDD)
J1 (D+) -> U1 (USB_DP)
J1 (D-) -> U1 (USB_DM)
J1 (CC1, CC2) -> 5.1kΩ resistors -> GND

Note that the AMS1117-3.3 regulator has a maximum input voltage of 15V and a dropout voltage of around 1.1V. Ensure that the input voltage from the USB-C receptacle is within the specified range for the regulator to function correctly.

U1 has the RUN pin unconnected, is that ok or will it cause problems?

nico

@copilot U1 has the RUN pin unconnected, is that ok or will it cause problems?

copilot

The RUN pin on the chip should not be left unconnected. If the RUN pin is not used, it should be tied high. Leaving it unconnected could lead to unpredictable behavior as the chip can be held in reset if the RUN pin goes low[1].

[1]: Page 170

how do I set GPIO1 from U1 in high impedance mode?

nico

@Copilot how do I set GPIO1 from U1 in high impedance mode?

copilot

To set GPIO1 of the RP2040 (U1 in your design) in high impedance mode, you need to configure it as an input and disable the internal pull-up and pull-down resistors. You can achieve this with the following Pico SDK C code:

C
#include "pico/stdlib.h"

int main() {
    // Initialize the library's internal data structures
    stdio_init_all();

    // Configure the pin as an input
    gpio_init(GPIO1);

    // Set the GPIO1 to high-impedance mode
    gpio_set_dir(GPIO1, GPIO_IN);
    gpio_disable_pulls(GPIO1);

    while (1) {
        // Your main program loop
    }

    return 0;
}

This code initializes GPIO1 as an input, then disables the internal pull-up and pull-down resistors, effectively setting the pin to high-impedance mode.

Please note that this configuration leaves the pin floating, so it might pick up noise if it's not connected to anything. Be sure to connect it to a defined voltage level before reading it or use it only for interfacing with high-impedance outputs.

how do I connect U3 to U1?

nico

@copilot how do I connect U3 to U1?

copilot

The RP2040 microcontroller (U1) and the W25Q128JVSIQ SPI Flash memory chip (U3) can be connected using the SPI (Serial Peripheral Interface) protocol. Here's how to wire them:

Connections:

Connect U3:~CS to U1:GPIO17. This is the Chip Select (CS) line, it's used to activate the SPI slave (U3).
Connect U3:DO(IO1) to U1:GPIO16. This is the Data Output (DO) line from U3 to U1.
Connect U3:DI(IO0) to U1:GPIO18. This is the Data Input (DI) line from U1 to U3.
Connect U3:CLK to U1:GPIO19. This is the clock line, it's used to synchronize data transmission.
Connect U3:IO2 and U3:IO3 to U1:GPIO20 and U1:GPIO21 respectively. These are used for Quad SPI communication which can increase the data throughput.
Connect U3:GND and U3:VCC to the common Ground and 3.3V power rail respectively.

Note: The GPIO numbers mentioned above are just examples. The actual GPIOs used may vary depending on the rest of your design. The important thing is to ensure that each SPI function from the memory chip is connected to a corresponding GPIO on the microcontroller and then correctly configured in software.

what's a good alternative for W25Q128JVSIQ? I want it to also be 128Mbit, have q...

nico

@copilot what's a good alternative for W25Q128JVSIQ? I want it to also be 128Mbit, have quad SPI and run at 133MHz. It doesn't have to be the same package.

copilot

A good alternative for the W25Q128JVSIQ would be the Micron Technology Inc.'s MT25QL128ABA1EW7-0SIT.

Here are its key features:

Memory Size: 128Mbit (16M x 8)
Clock frequency: Up to 133MHz
Interface: SPI, Quad SPI, DTR SPI
Operating temperature range: -40°C to +85°C
Package: 8-SOIC (0.209", 5.30mm Width)

You can find more information and purchase the component on various electronic component distribution websites.

Please note that you should always verify the compatibility of the part with your design requirements before making a decision.

can you recommend a suitable IMU for this project considering factors such as ea...

nico

@copilot can you recommend a suitable IMU for this project considering factors such as ease of use, cost, and available libraries?

copilot

Sure, for easy-to-use, cost-effective IMUs with good library support, especially for the Raspberry Pi Pico (RP2040), here are a few recommendations:

MPU-6050
- It's a 6-axis IMU with a 3-axis accelerometer and a 3-axis gyroscope.
- I2C interface, making it easy to connect and communicate with the RP2040.
- Plenty of code examples and libraries are available, including for the Raspberry Pi Pico.
- Very cost-effective.
Bosch BNO055
- A 9-axis IMU that includes a 3-axis accelerometer, 3-axis gyroscope, and 3-axis magnetometer.
- Has a built-in sensor fusion algorithm which can provide absolute orientation data.
- I2C interface.
- Has good library support, including a library from Adafruit which is well-documented.
- More expensive than the MPU-6050, but the additional features might be worth it depending on your project.
Invensense MPU-9250
- A 9-axis IMU with a 3-axis accelerometer, 3-axis gyroscope, and 3-axis magnetometer.
- I2C interface.
- There are several libraries available for this IMU, including for the Raspberry Pi Pico.
- Cost is moderate, more than the MPU-6050 but less than the BNO055.

Please remember to check the availability of these components as well, as this can vary.

I want to drive LED D1 from GPIO16. What current limiting resistor do I need and...

nico

@copilot I want to drive LED D1 from GPIO16. What current limiting resistor do I need and how do I design the buffer?

copilot

To drive a LED from a GPIO pin, you will need a current limiting resistor to prevent the LED from drawing too much current, which could damage both the LED and the GPIO pin. The value of the resistor can be calculated using Ohm's law: R = V/I, where V is the voltage drop across the resistor and I is the desired current.

In the case of the RP2040 microcontroller, the GPIO pins operate at 3.3V. The LED you've mentioned (IR26-21C_L110_TR8) doesn't have a provided forward voltage (Vf) or forward current (If) in the project context, so I'll use some typical values for a red LED as an example - Vf = 2V, If = 20mA. This means the voltage drop across the resistor should be 3.3V - 2V = 1.3V, and desired current is 20mA.

Plugging these values into Ohm's law gives:

R = 1.3V / 20mA = 65 ohms.

So you'd need a resistor of around 65 ohms. In practice, you might choose a standard resistor value of 68 ohms.

As for the buffer, you can use a simple NPN transistor as a current buffer. Connect the GPIO pin to the base of the transistor via a 1k ohm resistor, connect the emitter to ground, and connect the LED (in series with its current limiting resistor) to the collector. Be sure to choose a transistor that can handle the required current (at least 20mA in this example).

The purpose of the buffer is to protect the microcontroller from potential damage. The GPIO pin only needs to provide a small base current to the transistor, which then provides the larger current needed to drive the LED. This way, the GPIO pin doesn't need to supply the full LED current.

Please note these are example calculations. You should verify the forward voltage and forward current for your specific LED from its datasheet.

there are many power supply pins on U1. What's the simplest setup and what are i...

nico

@copilot there are many power supply pins on U1. What's the simplest setup and what are its disadvantages?

copilot

The simplest power supply setup for the RP2040 chip (U1) is to power it from a single 3.3V supply. Here are the details:

The digital IO (IOVDD), USB PHY (USB_VDD), and ADC (ADC_AVDD) will be powered directly from the 3.3V supply[7][6][5].
The 1.1V digital core supply (DVDD) will be regulated from the 3.3V supply by the on-chip voltage regulator. The regulator output pin (VREG_VOUT) must be connected to the chip's DVDD pins off-chip[6][5].

Disadvantages of this setup:

The on-chip voltage regulator is less efficient than an external switched-mode regulator. If you have a suitable external regulator available elsewhere in the system, or for low power applications, it might be more efficient to power the digital core (DVDD) directly from an external 1.1V supply[6].
Small transient currents may flow in the ADC supply (ADC_AVDD) if it is powered up before, or powered down after, the digital core supply (DVDD). This will not damage the chip, but can be avoided by powering up DVDD before or at the same time as ADC_AVDD, and powering down DVDD after or at the same time as ADC_AVDD[7][8].

[7]: Page 155 [6]: Page 155 [5]: Page 155 [8]: Page 155

what kind of oscillator do you recommend I use?

nico

@copilot what kind of oscillator do you recommend I use?

copilot

For the RP2040 microcontroller, I recommend using a 12 MHz crystal oscillator. The reason for choosing a 12 MHz oscillator is that it's a common frequency for USB devices, and the RP2040 supports USB functionality.

When selecting a crystal oscillator for your design, consider the following factors:

Frequency: 12 MHz
Load capacitance: Refer to the RP2040 datasheet for the recommended load capacitance value (usually around 8-30 pF)
Package size: Choose a package size that fits your PCB design constraints (e.g., HC-49, SMD)

Additionally, you'll need to connect the appropriate load capacitors between the crystal pins and ground to set the correct load capacitance for stable oscillation. To calculate the required load capacitor values, you can use the following formula:

C_L = \frac{C_1 * C_2}{C_1 + C_2} + C_{stray}

Where:

$C_L$ is the load capacitance specified by the crystal manufacturer
$C_1$ and $C_2$ are the load capacitors connected to the crystal pins
$C_{stray}$ is the stray capacitance of the PCB traces (usually around 2-5 pF)

, can you do a check for me? I want a list of unconnected pins with functions an...

nico

@copilot, can you do a check for me? I want a list of unconnected pins with functions and parts with the same designator.

copilot

Sure, I can help with that. However, I need to clarify your request:

When you ask for "unconnected pins with functions," do you mean pins that are expected to be connected because they have a specific function, but are currently unconnected?
When you ask for "parts with the same designator," do you mean components in the design that have duplicate designators which could cause confusion or errors in the design?

Please confirm or clarify these points, so I can provide the most accurate assistance.

nico

1- I mean all unconnected pins and what's the function of each pin so I can figure out if it needs to be connected. 2- Exactly

copilot

OK, let's get into it:

Unconnected pins with functions:

From U1 (RP2040):
- GPIO0 to GPIO15: These are general purpose input/output pins. They can be used for a variety of functions including digital read/write, analog read, PWM, and more.
- GPIO16 and GPIO17 are connected to LEDs and GPIO18 to GPIO29 are unconnected. These are also general purpose input/output pins.
- The pins named QSPI_SD3, QSPI_SCLK, QSPI_SD0, QSPI_SD2, QSPI_SD1, QSPI_CSN are for Quad SPI communication, typically used for fast data transfer with devices like flash memory.
- DVDD, IOVDD: These are power supply pins. DVDD is the core power supply, and IOVDD is the I/O power supply. These should be connected to the appropriate voltage level according to the datasheet.
- USB_DM, USB_DP are the USB data pins. They should be connected to the corresponding pins of a USB port for USB communication.
- The RUN pin is for resetting the microcontroller. It should be pulled high for normal operation and can be pulled low to reset the microcontroller.
- TESTEN: This pin is usually used for testing purposes during chip manufacturing. In normal use, it's typically left unconnected or tied to ground according to the manufacturer's instructions.
- SWCLK, SWD: These are used for Serial Wire Debug (SWD) communication. They should be connected to your debugger/programmer.
From U2 (AMS1117-3.3):
- TAB: This pin is usually physically connected to the GND pin and serves to help dissipate heat from the regulator. It should be connected to the ground plane of your PCB to help with heat dissipation.
From U3 (W25Q128JVSIQ):
- DO(IO1), IO2, DI(IO0), CLK, IO3, VCC: These pins are for communication with the flash memory. They should be connected to the corresponding pins on the microcontroller or other device that will be communicating with the flash memory.
From Q1 (NPN Transistor):
- B, C, E (Base, Collector, Emitter): These are the three terminals of the NPN transistor. How they should be connected depends on the use of the transistor in the circuit.
From J1 (USB-C Receptacle USB2.0):
- CC1, CC2: These pins are used to detect the orientation of the USB-C plug and to configure the port for USB power delivery.
- D-, D+: These are the USB 2.0 data lines.
- SBU1, SBU2: These are Sideband Use pins. They're used for alternate modes, like DisplayPort or Thunderbolt.
- VBUS: This is the power pin, which provides 5V power from the USB port.
- SHIELD: This pin should be connected to the ground to shield the USB connection from electromagnetic interference.
Parts with the same designator:
- I don't see any repeated designators in the components list provided. Each component has a unique designator. If you're seeing duplicate designators in your design, it could be an error in the component list or a mistake in the design.

how do I connect the shield pin to minimize EMI?

nico

@copilot how do I connect the shield pin to minimize EMI?

copilot

To minimize EMI (Electromagnetic Interference) when connecting the shield pin of the USB-C receptacle (J1), follow these guidelines:

Connect the shield pin to the PCB ground plane.
Use a local ground plane under the USB connector and around its traces.
Create a single-point connection between the local ground plane and the main ground plane to prevent ground loops.
Place a ferrite bead or a small-value resistor (e.g., 10 ohms) between the shield pin and the ground plane to further reduce high-frequency noise coupling.
Make sure the USB traces are impedance-matched, and avoid sharp bends and long traces as much as possible.
If possible, use a ground pour on both sides of the PCB to create a controlled impedance environment for the USB traces.

Ensure you follow the USB-C connector manufacturer's guidelines for best practices in EMI reduction.

I want to create an arbitrary waveform generator (AWG) with 8 gpio pins from the...

nico

@copilot I want to create an arbitrary waveform generator (AWG) with 8 gpio pins from the RP2040 and a resistor ladder. How should I calculate the value of those resistors?

copilot

To create an arbitrary waveform generator (AWG) with 8 GPIO pins from the RP2040, you can use an R-2R resistor ladder (also known as a DAC). An R-2R ladder is a simple, effective way to convert digital signals to analog.

Here's how you can calculate the resistor values:

Choose a standard value for R (for example, 10kΩ).
The value of the 2R resistors should be twice the value of R, so in this case, 2R would be 20kΩ.

With this configuration, each GPIO pin connected to the R-2R ladder will represent one bit of the DAC. The least significant bit (LSB, or Bit0) will be connected to the first stage of the ladder, the next significant bit (Bit1) to the next stage, and so forth, up to Bit7.

The output voltage (Vout) of the ladder can be calculated using the following formula:

Vout = Vin * (D / 2^n)

Where:

Vin is the input voltage (the voltage level of your GPIO pins, typically 3.3V for the RP2040)
D is the decimal number equivalent of the binary number represented by the state of the GPIO pins
n is the number of bits (in this case, 8)

Remember, the output of the DAC will be an analog voltage that is a fraction of the GPIO voltage level, depending on the binary number you output on the GPIO pins. If you need a voltage higher than the GPIO voltage level, you'll need to use an operational amplifier (op-amp) in a voltage-follower configuration to buffer the DAC output.

Please note that the speed at which you can accurately generate waveforms will be limited by how quickly you can change the state of the GPIO pins and how fast the DAC (R-2R ladder) can settle to a new voltage. This will also be dependent on the capacitive loading of the DAC output.

nico

What is the maximum samples per second that I'd be able to obtain?

copilot

The maximum sample rate you can achieve with a GPIO-based digital-to-analog converter (DAC) on the RP2040 is largely dependent on the speed at which you can toggle the GPIO pins.

The RP2040 has a clock speed of 133 MHz, but the actual GPIO toggle speed you can achieve is much lower due to the overhead of executing instructions to set and clear the GPIO pins.

Realistically, the GPIO toggle rate could be around 10-30 MHz. However, consider that for an 8-bit DAC, you'd need to update 8 GPIOs for each sample. Furthermore, the overall system performance, including the execution of other tasks and the speed of the language and libraries you're using, can significantly reduce the achievable sample rate.

Assuming you could achieve a conservative estimate of 1 MHz update rate for all 8 GPIOs together, you would have a maximum sample rate of 1 million samples per second.

Please note that this is a rough estimate and the actual sample rate could be higher or lower depending on various factors. Also, this doesn't take into account the settling time of the R-2R ladder network and the load on the DAC output, which can limit the effective maximum frequency of the output signal.

nico

The RP2040 has a DMA system that allows me to update all gpio pins at once in a single clock cycle. What is the maximum samples per second in that case?

copilot

If you're using the Direct Memory Access (DMA) to update all GPIO pins at once, you can considerably increase the effective sampling rate because the CPU would not be tied up in handling GPIO updates.

The DMA in the RP2040 can be clocked up to the system clock speed, which is 133 MHz. However, the actual effective rate will be lower due to the time taken for DMA setup and the fact that DMA operations are not instantaneous. The RP2040 datasheet does not specify the exact time taken by a DMA operation, but a conservative estimate would be that a DMA transfer might take a few (let's say 3-5) clock cycles.

Let's assume it takes 5 cycles per DMA operation, then the effective DMA operation rate would be 133 MHz / 5 = 26.6 MHz. This would be the rate at which you can update the 8-bit value on the GPIO pins using the DMA.

Please note that these are rough estimates. The actual achievable rate may be lower due to various factors such as overheads of setting up and triggering the DMA, other system operations, hardware limitations, and the settling time of the DAC circuit. It's also important to consider the effects of the DAC output load and the quality of the generated analog signal at high frequencies. You may need to apply some form of output filtering to get a clean analog signal.

nico

What if the DMA operation takes a single clock cycle?

copilot

If a DMA operation takes a single clock cycle, the maximum sample rate would be equal to the system clock speed because, theoretically, you could update the GPIO pins once per clock cycle.

The RP2040 has a system clock speed of 133 MHz. So, in theory, with a single-cycle DMA operation, you could achieve a maximum sample rate of 133 million samples per second.

However, it's important to remember that in a real-world application, there will be other factors that could limit the maximum achievable sample rate. These factors could include the settling time of the DAC circuit, the capacitive load on the DAC output, and other system operations that could affect the timing and performance of the DMA operations.

Also, note that achieving a clean analog signal at high frequencies may require some form of output filtering.

what's the best IMU?

nico

@copilot what's the best IMU?

copilot

Choosing the "best" IMU (Inertial Measurement Unit) depends on the specific requirements of your project, including factors such as cost, precision, power consumption, and size. However, here are few IMUs that are commonly used and highly rated:

MPU-6050: This is a popular choice for many hobbyists. It combines a 3-axis gyroscope and a 3-axis accelerometer on the same silicon die together with an onboard Digital Motion Processor™ (DMP) capable of processing complex 9-axis MotionFusion algorithms.
Bosch Sensortec's BNO055: This is a 9-axis absolute orientation sensor. It includes a triaxial 14-bit accelerometer, a triaxial 16-bit gyroscope with a range of ±2000 degrees per second, a triaxial geomagnetic sensor, and a 32-bit microcontroller.
Invensense's ICM-20948: It's a 9-axis MotionTracking device that combines a 3-axis gyroscope, 3-axis accelerometer, 3-axis compass, and a Digital Motion Processor (DMP) in a small 3x3x1mm package.
STMicroelectronics' LSM9DS1: It's a system-in-package featuring a 3D digital linear acceleration sensor, a 3D digital angular rate sensor, and a 3D digital magnetic sensor.

Remember, the best choice depends on your specific needs and the constraints of your project. Always make sure to read the datasheets and reference manuals for any component you plan to use.

what are the layout considerations for the analog pins on U1?

nico

@copilot what are the layout considerations for the analog pins on U1?

copilot

The RP2040 microcontroller (U1) has 36 multi-functional General Purpose Input / Output (GPIO) pins, divided into two banks. Among these, GPIO26 to GPIO29 can also be used as inputs to the chip's Analogue to Digital Converter (ADC)[1].

When designing the layout for these analog pins, consider the following:

Power Supply: The ADC requires a power supply with a nominal voltage of 3.3V (ADC_AVDD)[5].
GPIO Control: Each GPIO can be controlled directly by software running on the processors, or by a number of other functional blocks[3].
Pin Mapping: The PIO controls the output level and direction of up to 32 GPIOs, and can observe their input levels. The base and count of each range are configured via each state machine's PINCTRL register[4].

Remember to refer to the pinout reference and electrical specifications in the datasheet for full details on pin functions and locations[5].

[1]: Page 236 [5]: Page 12 [3]: Page 236 [4]: Page 317

I want to measure an analog signal with ADC0 from the RP2040. The signal goes fr...

nico

@copilot I want to measure an analog signal with ADC0 from the RP2040. The signal goes from 20mv to 1.5V, how do I choose ADC_AVDD voltage to get an optimal resolution?

copilot

The ADC_AVDD voltage on the RP2040 is the reference voltage for the ADC. The ADC on the RP2040 is a 12-bit ADC, meaning it can output values between 0 to 4095 (2^12 - 1). These output values are proportional to the input analog voltage in relation to the reference voltage (ADC_AVDD).

The ADC's resolution can be calculated with the following formula:

[Resolution = \frac{ADC_AVDD}{2^n - 1}]

where n is the number of bits of the ADC.

For optimal resolution, you'd want the ADC_AVDD to match the maximum voltage of your input signal. However, in this case, your signal's maximum voltage is 1.5V, which is less than the RP2040's maximum ADC_AVDD voltage of 3.3V.

If you set ADC_AVDD to 1.5V, the ADC's resolution will be:

[Resolution = \frac{1.5V}{4095} = 366.21 \muV/bit]

This means the ADC can measure voltage changes as small as 366.21 μV.

However, keep in mind that the actual ADC_AVDD voltage will depend on how you power the RP2040 and the noise and stability of the power supply. Also, the signal needs to be conditioned (amplified and offset) to match the ADC input range for optimal utilization of the ADC resolution. The 20mV lower limit of your signal will not be well-resolved if ADC_AVDD is set to 1.5V.

Remember to also consider the input impedance and the driving ability of the signal source when connecting it to the ADC. The ADC input can load the signal source and affect the accuracy of the measurement.

Please also check the RP2040 datasheet to confirm these details.

does this work to convert the 5v from USB to the 3.3V for the rp2040?

nico

@copilot does this work to convert the 5v from USB to the 3.3V for the rp2040?

copilot

Yes, the AMS1117-3.3 voltage regulator (U2) can be used to convert the 5V from USB to 3.3V for the RP2040 microcontroller (U1). The AMS1117-3.3 is a low dropout voltage regulator that can provide a fixed 3.3V output with up to 1A of current, which should be sufficient for the RP2040.

To connect the AMS1117-3.3 to the RP2040, follow these steps:

Connect the 5V from USB to the VI pin of the AMS1117-3.3.
Connect the GND pin of the AMS1117-3.3 to the GND of your circuit.
Connect the VO pin of the AMS1117-3.3 to the IOVDD and DVDD pins of the RP2040 to supply the 3.3V power.

Make sure to add decoupling capacitors close to the input (VI) and output (VO) pins of the AMS1117-3.3 as recommended in the datasheet for stability. Typically, a 10μF tantalum capacitor at the input and a 10μF tantalum capacitor at the output are used.

how do I make this resistor provide more current?

nico

@copilot how do I make this resistor provide more current?

copilot

The resistor closest to the current chat thread is R4 with a resistance of 65Ω.

Resistors don't provide current, but they control it. According to Ohm's Law (V = I*R), the current (I) through a resistor is inversely proportional to its resistance (R) for a given voltage (V). Therefore, to increase the current through a resistor, you would need to decrease the resistance.

For example, if you replace the 65Ω resistor with a lower value, such as 22Ω, the current flowing through that part of the circuit will increase, given that the voltage across the resistor stays the same.

However, please note that changing the resistor value will affect the operation of the circuit and should be done carefully considering the overall circuit design. Make sure the increased current doesn't exceed the maximum current rating of other components in the circuit, especially the LED (D1) in this case.

I used two in line resistors of 22 ohm on the USB DM and USB DP lines of U1, is ...

nico

@copilot I used two in line resistors of 22 ohm on the USB DM and USB DP lines of U1, is that correct?

copilot

Yes, using 22 ohm series termination resistors on the USB DM (D-) and DP (D+) data lines is common practice. This is done to match the impedance of the USB cable (which is typically around 90 ohms) and helps to prevent signal reflections that can degrade signal quality. These resistors are connected between the USB data lines (D+ and D-) of the USB connector and the corresponding pins on the microcontroller (in this case, the RP2040). In your design:

R1 is connected between U1:USB_DP and J1:D+
R2 is connected between U1:USB_DM and J1:D-

This setup is correct for USB impedance matching.

can you give me an alternative part for W25Q128JVSIQ?

nico

@copilot can you give me an alternative part for W25Q128JVSIQ?

copilot

Sure, an alternative to the W25Q128JVSIQ, which is a 128Mb SPI NOR Flash, could be the Macronix MX25L12833FMI-10G.

Here's a comparison of key specifications:

W25Q128JVSIQ (Winbond):

Memory Size: 128Mb (16MB)
Operating Voltage: 2.7V to 3.6V
Package: SOIC-8
Interface: SPI
Speed: 104MHz

MX25L12833FMI-10G (Macronix):

Memory Size: 128Mb (16MB)
Operating Voltage: 2.7V to 3.6V
Package: SOP-16
Interface: SPI
Speed: 133MHz

Please note that while these parts are functionally similar, the MX25L12833FMI-10G operates at a higher speed and comes in a different package, which may require changes to your PCB layout. Always check the datasheets and verify with your circuit requirements before making a substitution.

Here are the datasheets for both parts for your reference:

J1 D+ - U1 USB_DP

U3 CLK - U1 GPIO19

LED

U3 DI(IO0) - U1 GPIO18

U3 IO3 - U1 GPIO21

U3 ~CS - U1 GPIO17

3V3

LED

U3 IO2 - U1 GPIO20

Resistance

1KΩ

Resistance

22 Ω

Resistance

65 Ω

Reviews

Ground
A common return path for electric current. Commonly known as ground.
jharwinbarrozo
20.5M
Net Portal
Wirelessly connects nets on schematic. Used to organize schematics and separate functional blocks. To wirelessly connect net portals, give them same designator. #portal
jharwinbarrozo
43.0M
Power Net Portal
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 #power
jharwinbarrozo
11.4M
Generic Resistor
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 #CommonPartsLibrary
jharwinbarrozo
1.5M
Generic Capacitor
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 #CommonPartsLibrary
jharwinbarrozo
1.5M
Generic Inductor
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 #CommonPartsLibrary
jharwinbarrozo
15.8k
Terminal
An electrical connector acting as reusable interface to a conductor and creating a point where external circuits can be connected.
natarius
RMCF0805JT47K0
General Purpose Thick Film Standard Power and High-Power Chip Resistor 47 kOhms ±5% 0.125W, 1/8W Chip Resistor 0805 (2012 Metric) Automotive AEC-Q200 Thick Film Features: - RMCF – standard power ratings - RMCP – high power ratings - Nickel barrier terminations standard - Power derating from 100% at 70ºC to zero at +155ºC - RoHS compliant, REACH compliant, and halogen free - AEC-Q200 compliant
jharwinbarrozo
1.2M
875105359001
10 µF 16 V Aluminum - Polymer Capacitors Radial, Can - SMD 30mOhm 2000 Hrs @ 105°C #commonpartslibrary #capacitor #aluminumpolymer #radialcan
jharwinbarrozo
1.2M
CTL1206FYW1T
Yellow 595nm LED Indication - Discrete 1.7V 1206 (3216 Metric)
jharwinbarrozo
1.1M

Project Name

30 prompts in 30 days

Description

Design challenge: build a new PCB exclusively with Flux Copilot. Each day for 30 days, I'm using a new Copilot prompt to design a board with the RP2040.

Follow the Twitter thread: https://twitter.com/ntzova/status/1671868701954519041

Properties

Properties describe core aspects of the project.

Pricing & Availability

Distributor	Qty 1
Digi-Key	$2.13–$2.73
LCSC	$2.64–$3.28
Mouser	$2.24

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.

nico / 30 prompts in 30 days

Schematic

Introducing AI Placement!