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For the SC18IS600, what SPI command is for a Random Read coomand, Is one wants to read data from EEPROM address, RBTYE command doesn't work becuase it is for reading the current address that is setup with WBYTE 

Question asked by tom chin on Oct 5, 2017
Latest reply on May 2, 2018 by Suresh Kurukundi

I'm trying to read an EEPROM with the SC18IS600 device.

It was suggest by NXP support to append an additional byte that represent the EEPROM address to a regular BYTE command to perform this.

 

When I send the following SPI MOSI to the SC18IS600 for a RByte command

 

SPI-MOSI output

     RByteCMD - NByte - I2CAddr - EEPROM_addr

     0x01 -            0x01 -   0xA1 -       0x01

 

The SC18IS600, SDA output is as follow:

Start-bit  10100001  Ack  111111111  Stop-bit

 

The second SDA return byte from SC18IS600 is all High, which is not what I wrote into EEPROM Address 0x01.

The SDA stream never contains the EEPROM address 0x01.

 

What I noticed is that the SDA output the first Byte with a value = 0xA1 therefore this is the I2C protocol for a Current Address Read command and not a Random Address Read command. The SC18IS600 need to output a 0xA0 instead and I don't believe a command 0x01 would generate that.

 

The RByte command 0x01 doesn't work for this, please let us know what is the correct command sequence for a Random Address Read command.

 

The correct SDA sequence should be

Start-bit I2C_Addr R/W=0 ACK   Byte_Addr ACK  Start-bit I2C_Addr R/W=1 Data_out NACK

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