Mehrdad Amanabi

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9 years, 4 months ago.

i2c Frequency() function limit

Hi People,

I have a pair of simple code for two ST Nucleo boards I have, one is set as I2C Master-transmitter and the other one is Slave-receiver. the codes are working fine together, and I have verified results both on oscilloscope and also on PC terminal with default I2C frequency (100KHz).

I tried to increase the I2C Frequency to 300KHz, with frequency() function. The problem arises when I try to use "i2c.frequency(300000)" for master, and "slave.frequency(300000)" for slave. Even with default 100000 value, the communication won't establish.

Am I missing something with this function?

I appreciate any help with this.

2 Answers

Martin Simpson
9 years, 4 months ago.

Hi,

Might want to check you are using pull-up resistors on the SCLK and SDA lines (typically 2K Ohms approx. for 400KHz)

Regards

Martin

(BTW I checked my i2c and could change the frequency from 10KHz to 400KHz (Yes I did try 10KHz!) with 200 and 300 options all worked fine posted program list tagged under i2c and eeprom)

bco stm
9 years, 4 months ago.

Hi,

The available I2C frequencies on STM devices are : 100kHz, 400kHz and 1MHz (on some devices).

So try with 400 kHz instead of 300 kHz.

Regards.

If we give different frequencies other than the standard frequencies like what u mentioned, the chip is not executing the program, rather it just hangs

posted by BALAGANESH ARASIAH 13 Jun 2017