2010年3月13日 · According to the I2C bus specification The I2C pull up resistor value mainly depends on the I2C mode (Standard / Fast / Fast Plus / HS), VDD and the bus capacitive load. It's minimum value is calculated using the following equation: Rpmin = (VDD – VOLmax) / IOL. Where: VDD: Power supply voltage; VOLmax: Maximum LOW-level output voltage

A larger resistor means less current is needed, but the line will pull up more slowly (especially on a long line) and this may limit your rate. A smaller resistor pulls up faster, but at some point you'll burn out the driver pin (check the data sheet). 3.3K to 10K is probably fine; if …

I am trying to drive this I2C LCD display with an ATxmega16A4U microcontroller. Both devices are listed to work with I2C clock frequencies up to 400 kHz. The two devices are the only devices on the I2C bus. However, working out the calculations for the pull-up resistor bounds gives some rather odd values.

2021年12月30日 · Do I need pull-up/pull-down resistors on the SDA and SCL lines? Yes. 2k2-3k3 is fine. If you're using one of the off-the-shelf I2C peripherals like the LCD display, IO expanders, etc then warning: most of them require 5V, and ESP32 runs on 3V3. You must not connect the pullups on the ESP side to +5V, but to 3V3!

2015年7月27日 · Without pull-up resistors connected to the 2 lines of I2C, I2C communication fails. Why is there a need to have pull-up resistors for I2C? In contrast, UART and SPI do not need pull-up resistors.

2021年12月6日 · Graphs for the bus pull-up resistor values at different speeds and are given in the I2C bus specification. Take a look at that, you'll find it on the internet. Incidentally, please don't be tempted to post lots of little questions around the same problem as …

2015年7月1日 · I have a doubt in I2C pull up resistor. Actually I am developing a I2C module using GPIO pins. I have used external pull up resistor(10k) for the SDA and SCL lines. Do I need to enable the internal pull up also along with External pull up or external pull up is enough. How does the combined external and internal pull up effect the communication.?

\$\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). Suppose, you have a total of 3x (three) 2.2kΩ resistors as pull-ups. The total pull-up resistance is 733Ω. That violates I2C spec.

2014年3月12日 · \$\begingroup\$ Whether the devices use TTL or CMOS logic doesn' matter - normal TTL and normal CMOS outputs will pull signal both up and down. The I2C signals are either open-collector TTL, or (more likely) open-drain CMOS - in both cases, the transistor that would pull the signal high is missing from the output stage of the source, so pull-up ...

2016年6月5日 · I2C ideal pull-up resistor calculation. Ask Question Asked 8 years, 7 months ago. Modified 8 years, 7 ...