writing and reading from I2c eeprom ?

[RixtronixLAB]

Dear Members,

Where can I find from software development kit the example for writing and reading from I2C EEPROM ?

Thanks

[awneil]

An I2C EEPROM neither knows nor cares what microcontroller you use; all it sees is the transactions on the I2C bus - Start Conditions, Addressing, Stop Conditions; ACK/NAK, etc.

The Nordic SDK examples show you how to use the I2C (aka "TWI") hardware in the nRF52 - ie how to address a Slave, Read, and Write.

So you use the basic functions, together with the datasheet of your EEPROM, to generate the I2C transactions that the EEPROM requires.

For examples, see:

https://devzone.nordicsemi.com/f/nordic-q-a/70466/nrf52832-with-mpu9250-using-i2c-twi-on-sdk15-2-sd132-segger-embedded-studio/289159#289159

[RixtronixLAB]

There are 4 TWI examples

which one is the closest application with I2C EEPROM ?

This one

nRF5_SDK_17.0.2_d674dde\examples\peripheral\twi_master_with_twis_slave\pca10056\blank\arm5_no_packs ?

thanks

[RixtronixLAB]

I'm using :

nRF5_SDK_17.0.2_d674dde\examples\peripheral\twi_master_with_twis_slave

Please verify me ,

#define EEPROM_SIM_SIZE                   (2048u) //!< 24C16 EEPROM size

or 16384 ?

//#define EEPROM_SIM_ADDR                   0x50    //!< Simulated EEPROM TWI slave address.
#define EEPROM_SIM_ADDR                   0xA0    //!< AT24C16 EEPROM TWI slave address.

//#define EEPROM_SIM_SCL_S         31   //!< Slave SCL pin. <====Originnaly
//#define EEPROM_SIM_SDA_S         30   //!< Slave SDA pin.

#define EEPROM_SIM_SCL_S         27   //!< Slave SCL pin.
#define EEPROM_SIM_SDA_S         26   //!< Slave SDA pin.

Do I need to define WP (write protect) of 24C16, if I don't want to protect it ?

What does it mean by :

#define EEPROM_SIM_TWIS_INST     1    //!< TWIS interface used by EEPROM simulator.

?

is it possible to change it to TWI0, because port I use in my board is TWI0, I don't use TWIS

Currently my board is using :

// Arduino board mappings
#define ARDUINO_SCL_PIN             27    // SCL signal pin
//#define ARDUINO_SCL_PIN             NRF_GPIO_PIN_MAP(0,27)
#define ARDUINO_SDA_PIN             26    // SDA signal pin
//#define ARDUINO_SDA_PIN             NRF_GPIO_PIN_MAP(0,26)
#define ARDUINO_AREF_PIN            2     // Aref pin

How can I adapt it ?

I saw 2 defines at

eeprom_simulator_init();

and

err_code = twi_master_init();

thanks

[RixtronixLAB]

I got :

[1;37m[1;32muart_cli:~$ [1;37meeprom clear
                                 
[1;31mcommunication error
                                                    
[1;37m[1;32muart_cli:~$ [1;37meeprom clear
                                 
[1;31mcommunication error
                                                    
[1;37m[1;32muart_cli:~$ [1;37m                                               
                                         

what do I miss ? I use a real 24C16 chip

[awneil]

Is that what you're actually seeing on your terminal?

You need to remove the escape sequences to make that legible.

awneil said:

you should start with the TWI Scanner to verify your hardware connections, and Slave Address

[RixtronixLAB]

on TWI scanner, I can not find 0xA0, which is 24C16, what do I miss ?

nfo> app: TWI scanner started.
                                               

nfo> app: TWI device detected at address 0x3C.
                               

nfo> app: TWI device detected at address 0x50.
                               

nfo> app: TWI device detected at address 0x51.
                               

nfo> app: TWI device detected at address 0x52.
                               

nfo> app: TWI device detected at address 0x53.
                               

nfo> app: TWI device detected at address 0x54.
                               

nfo> app: TWI device detected at address 0x55.
                               

nfo> app: TWI device detected at address 0x56.
                               

nfo> app: TWI device detected at address 0x57.
          

[RixtronixLAB]

do i need pull up resistor on SCL and SDA on 24C16 ? thanks

[awneil]

You need pullups somewhere on the I2C bus - this is a basic requirement for any I2C bus.

[RixtronixLAB]

still can not see 24C16 address on TWI scanner, is my supply to low ? I checked, VCC=2.4V ?

[awneil]

Have you used an oscilloscope or analyser to see what's happening on the wires?

[RixtronixLAB]

Ok, I'll see with analyzer and posted, thanks

[RixtronixLAB]

I reckon, I have insufficient power for this 24C16 PU27, I will try with external 3.3V, I keep posted, thanks