The code to be run when the CPU is powered on needs to be stored in the ROM, but can the ROM be read and written when po

孤独的盗贼

I found a contradiction. The code to be run when the CPU is powered on needs to be stored in the ROM. Generally, read and write of the ROM needs to be initialized by the CPU. The ROM can be nor flash or eeprom. The flash must be set before it can be used. I2c can only be used if I don't understand

stylse

Who said that EEPROM must be configured with IIC first? EEPROM came out 800 years earlier than IIC!

孤独的盗贼

Even if reading and writing e2prom does not necessarily use i2c, can eeprom be read directly without any registers?

stylse

As long as the speed of the nor flash and EEPROM is not a problem, no register is required.

孤独的盗贼

If so, what does the flash driver have to do?

zgxz2000

Flash erasing and writing are more complicated, but reading is very simple, just give an address directly. Take a look at the chip manual, which contains a description of the control word and state machine.

leiren82

For nor flash, the read operation in low speed and non-burst mode is similar to sram/eeprom, so no driver is required. And nand flash needs to be driven regardless of reading and writing. Some cpus have a built-in nand flash controller, which allows the cpu to read nand flash to start the system when booting :)