M24SR64 with stm32

[fab04]

Hi everybody,

I'm working on a nucleo-L476. I'll like to write some data in NFC tag M24SR64 (I'm using a dev board ANT-7-M24SR).

First, I developped functions to read into ndef memoru on ESP32 dev board. It works well (I can read my message with ST app on cell phone).

So now, I try to transfer my code on STM32 platform.

First, I send byte 0x52 to select I2C mode. Then I send bytes to select NFC app and the problem is when I try to read M24SR answer, it always send me a nack answer.

My code :

/* kill RF, select I2C */
	HAL_I2C_Master_Transmit(&hi2c2,(NFC_ADDR_7BIT | WRITE_NFC),selectI2C,sizeof(selectI2C),TIMEOUT_NFC);
	HAL_Delay(1);
 
 
	//select NFC app
	HAL_I2C_Master_Transmit(&hi2c2,(NFC_ADDR_7BIT | WRITE_NFC),selectNFCApp,sizeof(selectNFCApp),TIMEOUT_NFC);
	HAL_Delay(1);
	HAL_I2C_Master_Receive(&hi2c2, (NFC_ADDR_7BIT | READ_NFC), tab_nfc, 5, TIMEOUT_NFC);

I'm doing something wrong, but I don't know what. If you have some ideas.

Thank you

[Ulysses HERNIOSUS]

Hi,

not an expert m24sr but I presume that analysis will be easier if you set I2C decoder to hex mode and possibly share the trace itself.

Best Regards, Ulysses

[Rene Lenerve · Accepted solution]

Hi @fab04​,

Another point to take into account is that the NACK could inform you that the I²C command has not finished to be processed. You could poll the I²C after each command by sending device address and waiting for an ACK before sending the next command. See DataSheet section 7 I²C device operation for more information.

You could use also the GPO for that instead of polling (not for GetI2Csession and KillRFsession).

Kind Regards.

[fab04]

By checking the datasheet, the last byte of reading operation is NACK, so that's normal.

I've also modify my way to read by adding function "HAL_I2C_IsDeviceReady", now it starts to work better.