stm32f4029 Disc Board I2C ACK not tracking

[k_vijay]

Hello Team,

I am using STM32F429Disc-1 board as development for I2C to integrate an eeprom (AT24CS04-SSHM-T).
In DSO I am getting proper SDA and SCL line, i.e Slave address and read/write bit and ACK on 9th clock pulse but in code I am getting an i2c error as 4 (I2C-ACK_FAILURE). Here I am attaching DSO screen shot fyr.



Target Board : STM32F429Disc-1
I2c Used : I2C2
Chibios Version : 21.11.x

The voltage level of ACK bit is 1.65v So I think it is consider as NACK by the controller. am I right or anything else is issue ?

[Giovanni]

Hi,

Do you have external pull-up resistors connected at master VCC? are I2C pins programmed as open drain?

Giovanni

[k_vijay]

Hello Sir

We have tried with external pull up register with 4.7K as well as 10K connected with 3v of board in both the case results are same.
I2c pins are programmed as with alternate function 4.
palSetPadMode(GPIOF,0,PAL_MODE_ALTERNATE(4))

[Giovanni]

Try adding PAL_STM32_OTYPE_OPENDRAIN to the mode but probably this is not it.

Anyway, the driver is sending the address, whatever is the problem is probably something else. You may also try lower resistors and a slower I2C speed.

Giovanni

[k_vijay]

Hello Sir,

We have lower the pull up registor value to 1K and the I2C speed is 100KHz. The result is same as the previous in waveform.

Do we need anything extra circuit need to add to make this eeprom work ?

[Giovanni]

I never used that EEPROM. You may try asking on the discord server if anybody has experience with it.

https://discord.gg/s8b8v7VtrM

Giovanni

[psyco]

It looks to me that or-ing PAL_STM32_OTYPE_OPENDRAIN with the alternate mode should be the solution. That ACK bit looks like the ST is pushing high while the eeprom is pulling low, especially with that spike at the end of it where the eeprom releases the bus.