I2c without pull up. For calculating the min and max values of the Mar 5, 2024 · How do you pick I2C pull-up resistor values? The common response is to choose anything between 1 kOhm and 10 kOhm. It limits the range of pull-up resistor values. Rise time (tr): Consider the waveform in Figure 4. The slaves are located at different locations in the PCB. Oct 28, 2016 · As such, there needs to be a default high which is commonly achieved with a 4. 1 General I2C Operation Dec 14, 2022 · So technically the schematics with dual pull-ups are not wrong, just the resistor values. The HMC5883L module has pull-up resistors on it already for both 5V and 3. the reason is that in most cases it is easier to have only one V+ connection and let the devices pull-DOWN the line to ground if they want For I2C communication there needs to be pull-ups on both COM and NC/NO pins to ensure the correct voltage is applied on both sides of the switch. Dec 23, 2020 · The standard is a maximum of 3 mA sink current to pull the signal low. 2 k pull-up resistor gives a reasonably good signal: Thus I don't think the resistors are the issue. A couple of things could be at work here: Jul 27, 2015 · Without pull-up resistors connected to the 2 lines of I2C, I2C communication fails. Messages are broken up into frames of data. Figure 4. 5V to register as a logic low signal. ESP32 has 2 I2C controller (also called port), responsible for handling Nov 10, 2022 · I'd like to understand the reasons on where the pull-up resistors should be placed for the I2C interface. Rule 1: The value can’t be too high. Mar 10, 2015 · I2C needs pullups. The desired behaviour: Input PA5 is ''high'' when switch is closed Input PA5 is ''low'' when switched is opened i tried to configure 2 Pullup Resistor Calculation. There are also some interesting tech docs on the one wire protocol about driving long Oct 29, 2023 · I2C No pull up found on SDA or SCL; check your wiring - XIAO - Seeed Forum. For example, if you use a CD4017 with a power supply of 10V, it requires a minimum of 7V May 7, 2018 · If you remove power from the chip leaving its I2C lines connected to the bus you are way over the safe limits, basically frying those chips. com. Nothing will be ruined of you try without additional pull-ups. 0 I'm controlling 48 Arduino's over I2C via a Raspberry Pi. Jul 16, 2018 · Whatever current source is bringing the line high in the absence of a true pull-up resistor, it is weak (ie, the circuit is very high-impedance) so it is also extreme susceptible to capacitive coupling from the clock line, hence you see the tops of the data line waveform showing artifacts when the clock switches. It’s important that the voltage is high enough for the chip to see it as a HIGH, or logical 1, input. 166 7. That would explain why I haven't needed them. The Arduino and the two MTi-3 are connected via breadboard as shown in the following picture (i hope it is Enable the I2C CLOCK and GPIO CLOCK. But I saw that people use 0,4V for 3mA. An I2C pull-up resistor connection. Another requirement is the external pull-up resistors (typically 4. With I2C, data is transferred in messages. You must disable those to prevent too much voltage on the I2C bus for your device. 9V on SCL. 7k). Then measure current between SCL and ground, repeat for SDA and ground. This will cause common errors such as the I2C address scanner reporting a response at every \$\begingroup\$ @SeinOxygen If you have modules with pull-up resistors, plus the controller with it's own pull-ups, then all these resistors will appear in parallel and present a stiffer pull-up (smaller resistance). Mar 9, 2021 · How To Choose a Pull-Up Resistor Value. When the series resistor is removed, the voltage on the MSP side of the SDA line should remain low during I2C communication without the pull-up resistor because the MSP only drives the SDA line low and puts the pin in a high impedance mode to allow the pull-up resistor to be connected from the I2C lines to the supply to enable communication as shown in Figure 1. Section 7 goes into the details of choosing the appropriate pull-up resistor, and this article will provide a real-world example of how to apply the concepts of that article. Sep 23, 2021 · The I2C pins are connected to the ATMEGA4809, and it is powered at +5V. Feb 18, 2017 · Use op open-drain outputs on I2C devices is required to avoid bus contention. Learn about I 2 C and some of the design challenges that comes with it, including logic thresholds, factors that affect capacitance, and minimum and maximum pull-up resistance. There are potential internal pullups, but not AFIK activated. I am not sure at all that the pull-ups within the AVR are compliant with I2C specifications (I think they are around 10k or 20k, I have to check in the datasheet) The Atmega 328 has built-in pull up resistors that can pull the output high when nothing is driving it. MAX32660 USER GUIDE UG6659; Rev 1; 07/2021. 7K to 10K for each I2C pin should be good enough. From what I read elsewhere, a pull-up of 4. Any device must be able to try to transmit at any time without the risk of damaging itself or other parts. P (min) CC - VOL (max) ) Nov 18, 2021 · answered Oct 5, 2020 at 10:34. SDA/SCL also need pullups that can be pulled down by the drivers that are meant to pull them down. The LWLP5000-5XD's I2C uses 5 V and uses 10k resistors. Configure the I2C PINs for ALternate Functions. Feb 19, 2018 · If you need pull-up just for buttons and similar inputs, 100k is pretty fine. So I need a level shifter. Jun 22, 2018 · June 22, 2018 by Mark Hughes. This leaves the bus floating, and the pull-up resistor will pull the voltage up to the voltage rail, which will be interpreted as a high. 3. Generally, the smaller the pull-up resistor, the faster is the rise of the signal to 1, but when driving a 0, there is also higher consumption. 8-3. 2 Pullup Resistor Calculation. sensors, pin, expansions, and drivers Nov 17, 2015 · My I2C sensor and my embedded processor do not agree on the logic level. 7K pull-ups. Oct 1, 2015 · View all videos. Following on the above, MCU does not output rail-to-rail. 7KOhm resistor on the lines pulling them default high. But it seems to be working with 2. Mar 11, 2021 · You can use this tool to calculate the minimum and maximum allowed values of the pull up resistors required for your I 2 C bus, based on the desired operation mode ( source ). 1. Figure 4 shows the flow of current through the pull-up resistor, which pulls the bus high. h>. Connect the 4 row (or col) pins to any 4 pins defined output. "1" does not mean you have slave Vdd at MCU Vdd and consequently, the I2C pull-up voltage. strong pullup (small resistor) prevents the I2C pin on an IC from being able to drive low. Apr 6, 2021 · 2. . Normally I would put a pair of pull-up resistors on the SDA/SCL lines. Another side question is how does one choose the value of the resistor? May 15, 2021 · For calculating the pull-up resistors I found this article from Texas Instruments. If you have many I 2 C devices on the same bus, you may need to adjust the equivalent value for the pull-up resistors by disconnecting the pull-up resistors on a few of the devices. 2k and 10k and see which works best. Suppose, you have a total of 3x (three) 2. Oct 20, 2021 · So, I understand like, suppose my I2C is running at 400kHz in both scenarios. RP(min) is a function of VCC, VOL (max), and IOL: ( V. They are used for projects that require many different parts (eg. I have a logic level converter between the RPi and the Arduinos however I am getting lots of noise on the line and suspect it's due to the pull up resistors on the Dec 17, 2020 · Since the pull-ups are to 5V on a SHT21 powered by 3. A simple switch is conected between the +5V source and the input pin. Use the required pull-up resistors. They may be present on your LCD-interface. In that case, only one set of pull-up resistors are required. You would have to desolder I2C pull-up resistors on SDA/SCL. How do I figure the I2C Oct 12, 2021 · To use the functions in the Wire library, we first need to add it to our sketch. 3V, after which there might be an internal protection diode that can push current from I2C pins to VDD, and if VDF is lightly loaded, the VDD voltage can rise somewhat too. g. Add a comment. 7) = 2. The datasheets says for arduino; VOL = 0,4 for IOL = 20 mA. Just use external 4k7 pull-ups to 3V3, the internal pullups won't be able to compete and it'll just work without modification. Each message has an address frame that Jul 9, 2021 · The formula is: Rp (min) = (V bus – V OL) / I OL. The higher the pull-up value, the lower the voltage on the input becomes. Dec 31, 2015 · Pull-up activation is done during port configuration (when you say if it's an input, an output or open drain with or without pullup) For I2C, you must have open drain with 2k2 pullup. 3V level onto the I2C line when no device is pulling it to GND, and limit the current when a device is pulling it to GND. Feb 8, 2017 · If 10 meters is considered a long distance, carefully set up I2C with constant current pull ups should do it. Or. I2C Logical High and Low. See Sparkfun 's introductory article. power dissipation: lower resistance reduces the RC time constant but increases the amount of current that flows from V DD to ground (through the pull-up resistor) whenever SCL or SDA is logic low. The value of the pullup resistor is an important design consideration for I2C systems as an incorrect value can lead to signal loss. How I2C Works. Why is there a need to have pull-up resistors for I2C? In contrast, UART and SPI do not need pull-up resistors. That violates I2C spec. But, still, how do you know the best value? The answer is related to the maximum number of devices you can have without using a repeater, switch, or multiplexer on an I2C bus. Although this difference is much less concerning than in #4. As depicted in Figure 21-1, both bus lines are connected to the positive supply voltage through. We would like to show you a description here but the site won’t allow us. P (min) CC - VOL (max) ) However, working out the calculations for the pull-up resistor bounds gives some rather odd values. With the level shifter in Pull-up resistors. Hi all! there is a weird behavior when trying to use I2C with my XIAO boards (nrf, ESP32) in circuitpython: RuntimeError: No pull up found on SDA or SCL; check your wiring. I'm trying to determine the minimum value of pull resistor for Arduino Uno. You can quite safely connect I²C to Raspberry P1 (3. The manufacturer doesn't not give a detailed datasheet about the I2C communication, only an application note saying you should test resistors with values between 2. e. Other info: nRF52480. If you want to achive 400kHz speed on I2C, even 4k7 might not work and you may need 3k6 or even lower. This is a very important equation because it is a function of rise time and bus capacity. Nov 14, 2010 · It would be nice to have a flag to disable the internal pull up resistors in i2c and implement external pull ups to 3. ard_newbie February 3, 2021, 2:15pm 2. Because the I2C bus need pullups for I2C chips that are on the same PCB as the microcontroller (MCU), even when remote I2C chips are missing or not connected! Below, the remote I2C chips might be optional. Oct 7, 2016 · According to my calculations the total pull-up is: 1 / (1/10 + 1/10 + 1/4. Adding internal pull-up or pull-down resistors to output pins is silly because they won't do anything except for wasting power. For example, many devices can pull the same signal low to indicate they need attention, but since no device pushes high, only a resistor does, so they can coexist on the same wire. you could define that 1 = HIGH and 0 = LOW (positiv logic). It depends on the total capacitance of all traces and devices attached. 1,645. answered Mar 19, 2020 at 13:08. My understanding is that I2C lines use pull-up resistors to passively pull up the bus to logic high because the drivers used on the bus are active drivers, namely open collector/open-drain. 0V on the SDA pin and 2. In this modes, pull-up resistors are not typically required. But if you use open-drain bus (e. The I 2 C bus uses only two bidirectional lines: SDA and SCL for each device for simple inter-IC communication. 5. Resistors do this, LEDs don't. 3V). The single Rule: An I2C device can only assert a low level on the bus. 4 3mA = 966. Feb 2, 2015 · The Uno has pullup resistors built in that pull the SDA and SCK to 5 volts. The typical pull up value for the STM32 microcontrollers is 40 k Ω Ω (assuming they're even active). Considering the position of both I2C pins to each other and the VCC pin, I was thinking of simplifying Since OpenBSD 3. According to the datasheet both pin 5 (SDA) and pin 6 (SCL) need an external pull-up. 7Ω R m i n = V c c − 0. Apr 6, 2021 · Problem #8 - Pull-up resistors and bus capacitance The I2C bus is designed to be driven only through open-drain connections pulling the bus down, it is pulled up by a pair of pull-up resistors (one on the clock line and one on the data line). For that, you’ll still need to spec an appropriate pull-up resistor. e) Configure the Alternate Function in AFR Register. Leo. UART/I2C Pull up resistors. See this schematic. If the resistors are not connected to the same 3. Minimum Pull-up Resistance. If this possible? I can see how to configure them for GPIO, but I'm wondering if I use the same approach if it would interfere with the UART/I2C drivers. Now you know logic voltage and pull up current. The data line is allowed to change when the clock is low. Apr 20, 2015 · 1. For the normal i2c bus (100kHz to 400kHz) every device should at least be able to sink 3mA, but is allowed to sink more. b) Select Open Drain Output. (VDD = 5V) For formula for calculation of minimal pull-up is: Rmin=Vcc−0. One of the MTi-3's is placed on a Development Kit, which has integrated 2k7 pull-up resistors for I2C communication. The kyypad is a 4x4 matrix. Feb 3, 2021 · Thank you, Andrei. Users are not bound to use I2C with pre-set pull-up values. Nov 30, 2014 · answered Nov 29, 2014 at 22:21. The “Low Input Level Voltage”, r L, is 0. I2C is an open-collector bus, it requires pull-up resistors to hold the clock and data lines high and create the data ‘1’. pull-up resistors. In this Workbench Wednesdays video, I show how to estimate I2C bus capacitance, measure that capacitance, and pick pull-up resistor values. Dec 19, 2018 at 7:12. This is due to the fact that a pull-up resistor is primarily used to pull-up 1 circuit node. Calculating the I2C minimum pullup resistor value: Rmin = Vcc − 0. Dec 13, 2022 · Hi, i have an Arduino Portenta H7 Lite connected two Xsens MTi-3 IMU's to it. The pullups are what drives the SDA/SCL signals high. 4 3 m A = 966. As an example, we will use an EFM8LB1 MCU, operating at VIO = 3. For more information about this property, consult the NI-845x Hardware and Software Manual on section 3-10 for 8451 and section 3-18 for 8452. I2C is idle high. 5V to register as a logic high signal, and below 1. Looking at the uC datasheets, on page 92 lists the max pin input capacitance of 10pF. I2C), then resistor values have to be calculated properly. Oct 12, 2021 · To use the functions in the Wire library, we first need to add it to our sketch. 3 x Vdd. Aug 2, 2012 · Re: Does i2c need pullups (resistors, not diapers!) Sat Dec 28, 2013 6:47 pm. c) Select High SPEED for the PINs. 3V, but if I wanted to add my own external pull-up resistors, then I would have to reference it to 5V as shown in my block diagram, correct Feb 8, 2017 · Note that this solution only mitigates noise, and does nothing to solve the issue of bus capacitance. The I2C spec is well known and defined by NXP in the UM10204 specification, available as a PDF here from the NXP website. The most important hardware parts are pull-up resistors, which are used by the SDA and SCL lines. 3V with an I2C speed of 400 kHz (fast mode), for the I2C bus characteristics. 3V supply, but for example two different 3. Figure 2. So, when we hook everything up to our Arduino, we need to ensure that our SCL and SDA lines are above 3. This is from page 215 of the Atmel datasheet. 8k pullups on each line and each Arduino has a 10k internal pullup. And I don't see how adding more would "calm the whole I2C constellation a bit". The address is optional for master devices. I2C parts don’t output high, they only pull low, without pull-up resistors there can never be a ‘1’. And if the devices are placed far apart, it would take a little more time to charge the bus capacitance and to avoid this extra time, we need to have a strong pull-ups (Low pull up resistor values) on the SDA and SCL lines. Releasing the Bus With An Open-Drain Interface 2 I2C Interface 2. P (min) CC - VOL (max) ) From the datasheet: RBPU: PORTB Pull-up Enable bit. It is a serial communication interface with a bidirectional two-wire synchronous serial bus normally consists of two wires – SDA (Serial data line) and SCL (Serial clock line) and pull-up resistors. It is based on the official I 2 C bus specifications and is taking under consideration the constraints set for each mode. Where tr means rise time of both SDA and SCL signals and Cb means capacitive load for each bus line. The output pin is equivalent to a 0-ohm pull-up or pull-down resistor already (depending on whether your software makes it high or low). I have seen many a young engineer struggle with unreliable I2C communication due to either the entire Nov 7, 2022 · Part Number: TXS0108E Hi team, my customer wants a solution that support both GPIO and I2C , but don't need external pull-up resistor at the same time. A device would check that the data line is high before using the bus. The clock signal is always controlled by the master. I have used external pull up resistor(10k) for the SDA and SCL lines. I2C uses two bidirectional open-drain lines: serial data line (SDA) and serial clock line (SCL), pulled up by resistors. I2C is a serial, synchronous, multi-device, half-duplex communication protocol that allows co-existence of multiple masters and slaves on the same bus. The 4 col (or row) pins connects to any 4 pins defined input_pullup. (MCU --> resistors --> local I2C chip (s) --> connector) Jul 1, 2021 · The DS1337 is an 8 pin IC with VCC at pin 8 and GND at pin 4. begin(address). The RPi has 1. nRF Connect SDK v2. This is not a stop condition. May 22, 2021 · So, each bus would need its own pull-up resistors. The syntax for this is Wire. Since I am really new to all this (I2C, calculating pull-up resistors for a bus, logic level conversion etc. 1. In the sketch above, we do that with #include <Wire. programmatically or manually disconnect the resistors from the two lines? Oct 31, 2012 · When connecting multiple I2C devices/slaves to the Arduino do I need pull-up resistors at each slave or is one set of pull-up resistors enough. The Pi's SDA and SCL lines have physical resistors on the board to pull up to 3. The pull-up resistor will assert the 3. You can calculate a correct value, but if you just want to get working, a 4. Mar 19, 2020 · Output pins output a certain voltage. Share. Also, unlike SPI, I 2 C can support a multi-controller system, allowing more than one controller [1] to communicate with all peripheral [1] devices on the bus (although the controller devices can't talk to each other over the bus and must take turns using the bus lines). Feb 24, 2013 · After a lot of reading: does the UNO Rev 3 board have on-board pullup resistors for the I2C lines A4 and A5; 10K from what I read? I can't find them on the schematic. Actually I am developing a I2C module using GPIO pins. Feb 9, 2013 · Hello; i have problems to understand how to configure an GPIO input port correctly. ) I am not sure if external pull-up resistors are required in my case. Dec 15, 2020 · The maximum pull-up resistance is the function of the maximum rise time (tr). Yes, you need external pull up resistors. 2. 3volt or 5volt-logic. Jul 1, 2015 · I have a doubt in I2C pull up resistor. Last Jan 7, 2023 · First measure voltage on the I2C pins, to see if it's internals work with 3. It depends on how big the pull-up resistor is and how fast you want to go with I2C. What i wan't: Port PA5 shall be configured als input port. 423 k As I show on my page about I2C a 2. You also can define, that if nothing is send, the line should be 0, so you need a pull-DOWN. If Beaglebone designates those pins as usable for I2C, the internal pull-up resistor is most likely sufficient. The voltage drop across the resistor will in practice either be none (when no connected device is pulling the line down), or nearly the entire line voltage, since the resistance of the Dec 20, 2015 · The trade-off is speed vs. If current is being drawn this would indicate that the line is being driven low by a device on the line. Also can these pullups be disabled - i. 3V VDD, the voltage on I2C pins will exceed the nominal maximum of VDD, and most likely will exceed the absolute maximum rating of VDD+0. 0 = PORTB pull-ups are enabled by individual port latch values. Assume a PCB, where I have one I2C master and multiple I2C slaves. I need pull-up/pull-down resistors on my UART and I2C lines and am wondering if I can enable the pull-up/pull-down resistors instead. The RPi is 3v3 and the Arduino is 5v. joan wrote: I believe the answer to be yes, the resistors are necessary. This article looks at the mathematical calculations used to size the pull-up resistors and determine the maximum length of circuit traces. However for the LCD, it has on Jun 5, 2016 · I2C Pull-ups with Multiple Power Supplies. This is important because the optimal pull-up value can vary depending on different factors. Since the switch has resistance and capacitance it splits the I2C bus into multiple nodes. 7 k Ω Ω resistor will get you started. Pullups are definitely required. Full Notes on Feb 13, 2016 · Like SPI, I2C is synchronous, so the output of bits is synchronized to the sampling of bits by a clock signal shared between the master and the slave. – Jot. SDA1/SCL1 have no pull-ups. I 2 C requires a mere two wires, like asynchronous serial, but those two wires can support up to 1008 peripheral devices. the “High Input Level Voltage”, r H, is 0. Nov 30, 2017 · Hi George, It doesn't look like there is anything out of place on your schematic on the I2C lines between the MSP and RT9528. 3V. The official I2C specification (page 9) states that a voltage is not considered “logic high” until it reaches 70% of V DD. After including the library, the next thing to do is to join the device on the I2C bus. a) Select Alternate Function in MODER Register. . Abstract: This user guide provides application developers information on how to use the memory and peripherals of the MAX32660 microcontroller. Ignoring capacitance and allowing for the standard 3mA current when the line is pulled low, 367 ohms to 1. 9 (released 1 May 2006; 18 years ago ()), a central i2c_scan subsystem probes all possible sensor chips at once during boot, using an ad hoc weighting scheme and a local caching function for reading register values from the I 2 C targets; this makes it possible to probe sensors on general-purpose off-the-shelf i386/amd64 Sep 26, 2019 · I²C stands for Inter-integrated-circuit. To figure out why let's look at how I2C works. 2kΩ resistors as pull-ups. Mar 7, 2024 · At those speeds, the pull-up resistor and the bus capacitance form an RC filter that fundamentally limits the data transmission speed. pull-down FET. d) Select Pull-up for both the Pins. The pullup resistors pull the line high when it is not driven low by the open-drain interface. Nov 6, 2023 · The I2C designated pins can also be used as General Purpose Input/Output (GPIO) pins or for Analog-to-Digital Conversion (ADC). Do I need to enable the internal Most I 2 C devices offered in the SparkFun catalog usually include pull-up resistors for the SCL and SDA pins. answered. The other MTi-3 is placed on a PLCC28 socket adapter and i added the 2k7 resistors manually. These calculations apply to. Every device may be able to sink more, but a manufacturer of a sensor can build a sensor that can sink only 3 mA to comply with the I2C standard. Am I correct? \$\endgroup\$ – Feb 8, 2022 · The I2C spec (NXP UM10204) gives equations for this. 2 V on the bus when configured as input. 7 x Vdd. Pull-up resistor value I2C; higher than 400 pf capacitance. When I look a different examples I see both setups. 4V/20mA = 4,6V / 20mA = 230 ohms. That said, the board you've linked that breaks out the multiplexer chip has pull-up resistors on each bus that it's providing: The breakout also has pull-ups on the bus going to the multiplexor itself: Beyond that, the ambient light sensor breakout seems to provide its own 4. To fix the problem I trust both pins SDA and SCL must have 2. No. The problem is that there is stray capacitance on the I2C wiring that has to be charged, and this takes time. P (min) CC - VOL (max) ) I2C is a serial, synchronous, multi-device, half-duplex communication protocol that allows co-existence of multiple masters and slaves on the same bus. 17. so Let's look at the higher side Voltage device asserting a low: On the FET, a low voltage is provided on the Drain, this forward biases the body diode, and allows for a diode above gnd to be seen on the Source. 7,939. Learn about the pull up resistors used with I2C Bus and the calculations involved to determine the correct value of those resistors. The 50K pull-up resistors built in to the Atmega take a long time to do this, much more time that is allowed for in the I2C Jan 9, 2014 · it depends on design: e. i2c uses also positiv logic (1=HIGH, 0=LOW) but let the line HIGH on IDLE. The VOL level that can be read as a valid logical low by the input buffers of an IC determines the minimum pullup resistance [RP(min)]. Open-collector (or open-drain) outputs are needed for many reasons. The entire purpose of the pullups is to keep the line high - I2C I/O is open drain and the devices are incapable of driving the line high, only pulling it low. 2022-02-08 06:24 AM. Thus, the I2C lines are referenced to a voltage of 5 volts. Since open collector/open-drain drivers can drive the line low but not high, the issue of bus contention is mitigated. Oct 4, 2022 · PLF2135's I2C uses 5 V and requires pull-up resistors. Working out pull up resistance is a matter of using ohms law. In our ESP32 story, do we need explicit external pull up resistors or is this taken care of for us by configuring I2C or do we need to explicitly define the mapped pins as pulled-up or some other story. I do not have any issue when using Arduino code only in Apr 21, 2023 · For NI-8451: With this device you have to use an external pullup resistor since NI-8451 doesn't support to set I²C Pullup Enable to true. For Fast-mode I2C communication with the following parameters, calculate the pullup resistor value. May 28, 2019 · Re: i2c pull-ups current. That is for the normal 100 kHz to 400 kHz I2C bus. 3V supply where the other supply can be turned off by the MCU, then it will be a completely different, larger problem. Some manufacturers make devices that barely can do 3mA, so the pullup resistor should keep the current to pull the signal low to 3mA or less. Sep 17, 2023 · SDA/SCL need pullups that will keep supplying current to charge the line capacitance all the way up to the pullup voltage. I2C devices have open-drain connections to the bus, meaning that they can not drive a high signal, they can only drive it low or "release" it. If you need more I/O pins than you get on a DUE, and still use a DUE, there may be a workaround: The DUE core is 100% arduino DUE compatible and all 144 pins are broken out: inhaos. 1 = All PORTB pull-ups are disabled. They conduct only a miniscule leakage current at slightly below their nominal voltage. Thanks. dertobias October 29, 2023, 9:25pm #1. The total pull-up resistance is 733Ω. 7k. 1V would be the highest usable value. 7 Ω. Formula 1. uu th sx xr dz hg nc do di wb