I2C pull-up and serial resistor

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Registriert: 31 Okt 2010, 22:23
Wohnort: Enschede (NL)

I2C pull-up and serial resistor

Beitrag von vleeuwen » 02 Jul 2019, 20:00

In the TXT manual (English pag. 29) the description of the I2C is not complete.

IS the TXT SDA and SCL an open collector configuration or have they already pull-up resistors Rp (? k ohm)?

This can be interesting for calculating the right vale for the Rp.
see [1] Chapter 7
Has the TXT SDA and SCL also a Rs (serial resistor)? And what value?
see [1] Chapter 7.3

See also:
[1] the I2C bible from NPX, the I2C manual https://www.nxp.com/docs/en/user-guide/UM10204.pdf
[2] https://www.i2c-bus.org/
[3] Level shifter explained
https://www.nxp.com/docs/en/application ... N10441.pdf

AlexanderSteiger ft
fischertechnik Mitarbeiter
Beiträge: 27
Registriert: 09 Aug 2017, 08:39

Re: I2C pull-up and serial resistor

Beitrag von AlexanderSteiger ft » 02 Aug 2019, 12:00

The TXT I2C on EXT plug is not an open collector configuration.

SDA and SCL both have already a Rs (serial resistor) and Rp (pull-up resistor)

Rp = 4k7 Ohm
Rs = 100 Ohm

Kind regards,
Alexander Steiger