Booting LPC55 via I2C, can we trigger flash-boot via rom-loader?

[dav1]

When using the built-in I2C "ISP boot mode" of the LPC55 series cpu's
is it possible for the host to signal via I2C to immediately exit the rom based bootloader to continue booting via flash?

I don't have the option to add a dedicated gpio to control ISP, so idea was to always enter the rom boot mode -> read flash region to check installed firmware -> if up to date -> continue to boot via flash

doable?

[dav1]

thanks, sounds good!

do you have an idea of how long it will take to run these commands over i2c?

i couldn't find any wait times in the datasheet so should be fairly instant (i hope)

[jay_heng]

Yes, you can try read-memory and execute commands in UM 8.9.5 I2C ISP commands

Use read-memory command to read back app data from internal flash

Use execute command to jump to app

[dav1]

having trouble with this, the UM 8.9.5 doesn't have an example so tried this:

boot_cmd[22] = {0x5A,0xA4,0x10,0x00,0x00,0x00,0x09,0x00,0x00,0x03,0x6c,0x01,0x00,0x00,0x00,0x80,0x01,0x20,0x00,0x80,0x01,0x20}

where 0x09 is the execute cmd, but the response code is command not supported