SAMA5D28 customboard:how to reset Boot Config word FUSE bits

Discussion around products based on ARM Cortex-A5 core.

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ganesha.ld
Posts: 34
Joined: Mon Dec 19, 2011 7:01 pm

SAMA5D28 customboard:how to reset Boot Config word FUSE bits

Wed Sep 27, 2017 11:55 am

Hi,

I'm Using SAMA5D28 custom board. Using sam-ba_3.2.0 for programming.

We also have signed NDA with microchip and have got the "Secure Boot Strategies" documentation and Secure sam-ba-loader and secure-sam-ba-cipher. And also got the secure sam-ba "licence" for my PC.

By mistake wrong fuse values are set and I'm not able to revert them back.

is there any way to RESET the "Boot configuration word" register FUSE bits to default? OR these "Boot configuration word" register FUSE bits only OTP bits?

I want to enable BSCR, SPI0_IOSET1, NANDFLASH(IOSET2), and SDMMC1..

Here are the fuse readings:

ganesh@ganesh-14# sudo sam-ba -p usb -d sama5d2 -a bootconfig -c readcfg:fuse
Opening serial port 'ttyACM0'
Connection opened.
Executing command 'readcfg:fuse'
FUSE=0x00440fff / QSPI0_DISABLED,QSPI1_DISABLED,SPI0_DISABLED,SPI1_DISABLED,NFC_DISABLED,SDMMC0_DISABLED,SDMMC1_DISABLED,UART1_IOSET1,JTAG_IOSET1,EXT_MEM_BOOT,DISABLE_BSCR
Connection closed.
ganesh@ganesh-14#


I tried the following command to enable the appropriate bits in the fuses:

ganesh@ganesh-14# sam-ba -p usb -d sama5d2 -a bootconfig -c writecfg:fuse:ext_mem_boot,sdmmc1,sdmmc0_disabled,nfc_ioset2,spi1_disabled,spi0_ioset1,qspi1_disabled,qspi0_disabled
Opening serial port 'ttyACM0'
Connection opened.
Executing command 'writecfg:fuse:ext_mem_boot,sdmmc1,sdmmc0_disabled,nfc_disabled,spi1_disabled,spi0_ioset1,qspi1_disabled,qspi0_disabled'
Setting FUSE to 0x000407cf (QSPI0_DISABLED,QSPI1_DISABLED,SPI0_IOSET1,SPI1_DISABLED,NFC_IOSET2,SDMMC0_DISABLED,SDMMC1,UART1_IOSET1,JTAG_IOSET1,EXT_MEM_BOOT)
Connection closed.

ganesh@ganesh-14# sam-ba -p usb -d sama5d2 -a bootconfig -c readcfg:fuse
Opening serial port 'ttyACM0'
Connection opened.
Executing command 'readcfg:fuse'
FUSE=0x00440fff / QSPI0_DISABLED,QSPI1_DISABLED,SPI0_DISABLED,SPI1_DISABLED,NFC_DISABLED,SDMMC0_DISABLED,SDMMC1_DISABLED,UART1_IOSET1,JTAG_IOSET1,EXT_MEM_BOOT,DISABLE_BSCR
Connection closed.

Again its the same fuse values.. :( :(
Please help me in regarding this issue..
Thanks,
-Ganesh
blue_z
Location: USA
Posts: 1560
Joined: Thu Apr 19, 2007 10:15 pm

Re: SAMA5D28 customboard:how to reset Boot Config word FUSE

Thu Sep 28, 2017 12:22 am

> is there any way to RESET the "Boot configuration word" register FUSE bits to default?

No.
The datasheet is terse but clear:
The default value of a fuse is logic ‘0’ (not programmed). A programmed fuse is logic ‘1’.
...
Each fuse in the matrix can be programmed only one time.
A blown fuse cannot be restored to its original unprogrammed state.

Regards

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