topic Re: LPC1765 I2C EEPROM does not return ACK in LPC Microcontrollers

LPC1765 I2C EEPROM does not return ACK

Ronaa — Mon, 19 Feb 2024 14:36:46 GMT

We try to control 24Lc16 EEPROM using I2C0 on LPC1765.

We can see the address going out on the bus, but no ACK is received after the address.

We have 4.7k pull up resistor on SDA and SCL.

I2C1 seems to work fine with the same configuration.

What can be the problem here?

Re: LPC1765 I2C EEPROM does not return ACK

xiangjun_rong — Tue, 20 Feb 2024 03:49:18 GMT

Hi,

As you know that the I2C of LPC1765 is master, after the 7 bits I2C slave address+W, the EEPROM must provide the ACK signal.

Pls check the EEPROM and check if the slave address of EEPROM is correct.

Can you tell us the part number of third party EEPROM?

Hope it can help you

XiangJun Rong

Re: LPC1765 I2C EEPROM does not return ACK

Ronaa — Tue, 20 Feb 2024 05:51:20 GMT

The slave i write is 0XA0 and this is what is should be according the the EEPROM data sheet. the device is AT24LC16.

We try to write 3 times and get 0X20 the the status register. we also try to read, but the response is the same.

I attach the scope image, it looks a bit different than what I expected, but it can be scope problem, not bus problem

Re: LPC1765 I2C EEPROM does not return ACK

frank_m — Tue, 20 Feb 2024 07:15:36 GMT

> The slave i write is 0XA0 ...

A common source of misunderstanding and confusion is the definition of this address. As mentioned, it is 7 bit, not 8 bit.
The datasheet either expects an AND operation with the RW-bit, or implies a left-shift of this address by one bit. Often, these datasheets reveal this only indirectly, in either their figures or waveform examples.

The easiest way would be to try out both.

Re: LPC1765 I2C EEPROM does not return ACK

Ronaa — Tue, 20 Feb 2024 08:43:27 GMT

Thanks all for the quick help. using 0x50 instead of 0xA0 works.