ROM Bootloader - MKL27Z32VFM4

Kantha — Wed, 10 Aug 2022 10:22:50 GMT

Hi,

We are planning to use the feature of ROM bootloader on the part MKL27Z32VFM4 in production.

I do see ROM bootloader is available in KL27Z series microcontrollers as given below link

https://www.nxp.com/design/software/development-software/mcuxpresso-software-and-tools-/mcu-bootloader-for-nxp-microcontrollers:MCUBOOT

Could you please confirm ROM bootloader is available on the part MKL27Z32VFM4?

Thanks,

Kantha

Re: ROM Bootloader - MKL27Z32VFM4

bobpaddock — Wed, 10 Aug 2022 14:25:02 GMT

Yes the KL27 has the ROM bootloader built in.

To work around a bug it has call this function right out of reset:

static void vectors_bootloader_mr_setup( void ) __attribute__( ( used, __aligned__( 4U ), section( ".after_vectors" ) ) );
static void vectors_bootloader_mr_setup( void )
{
/*
* RCM_MR Indicates the boot source, the boot source remains set
* until the next System Reset or software can write logic one to
* clear the corresponding mode bit. While either bit is set the
* NMI input is disabled and the vector table is relocated to the
* ROM base address at 0x1C00_0000. These bits should be cleared by
* writing logic one before executing any code from either Flash or
* SRAM.
*
* A reset is forced to clear out anything that the ROM
* bootloader did, so we are sure we have the data sheet reset
* values.

* This method works around the buggy KL43/27/17 bootloaders as
* described in: "Problem Analysis and solutions for booting from
* ROM BOOTLOADER in KL series".
*/
if( 0U != ( RCM_MR & RCM_MR_BOOTROM_MASK ) )
{
RCM_MR = RCM_MR_BOOTROM_MASK; /* Clear the bits that indicated a bootlaoder boot via ROM */
RCM_FM = 0U; /* Boot from Flash not ROM on next reset */

SCB_AIRCR = ( SCB_AIRCR_VECTKEY( 0x05FAU ) | SCB_AIRCR_SYSRESETREQ_MASK ); /* Force a Software Reset */
}
}

Also in case you are not aware the KL27 has problems with I2C repeated-start. It is discussed in the forum here. The IDE inserts undocumented NOPs to work around the race condition.

See Appendix-A in Mark's document:

https://www.utasker.com/docs/uTasker/uTasker_I2C.pdf

topic ROM Bootloader - MKL27Z32VFM4 in Kinetis Microcontrollers

ROM Bootloader - MKL27Z32VFM4

Re: ROM Bootloader - MKL27Z32VFM4