Jun 13, 2019
12:43 AM
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Jun 13, 2019
12:43 AM
Hello forum,
we plan to integrate the flash read protection feature into our product using a XMC4300. I'd like to make sure my plans are correct before start.
We use a bootloader (placed in first 16 kB of flash), which receives the firmware (on UART). The bootloader will install the global read protection on-demand (by a command). For application firmware update, it will use the "Disable Read Protection" (see table 8-4 in XMC4300 manual) flash command before update and the "Resume Protection" (table 8-4) command after successful update.
To be able to exchange the bootloader itself (e.g. by JTAG-interfaced J-Flash), I need to remove the read protection permanently by erasing UCB.
1) I understood that installing the read protection requires writing the User Control Block (UCB) for user 0. It is only possible to write to that UCB 4 times, even if I only access user 0? (User 0 contains the global read protect bit.)
2) Does disabling the read protection automatically erase the full chip or do I need to make that happen manually?
3) When I'd like to attach JTAG again, will a temporarily disabled read protection (by "Disable Read Protection" command) work? I assume the JTAG connect command will perform a controller reset, which will re-enable the read protection again, will it?
4) Does the enabled read protection affect the ability to read flash in my bootloader itself?
Best regards,
Ernie T.
we plan to integrate the flash read protection feature into our product using a XMC4300. I'd like to make sure my plans are correct before start.
We use a bootloader (placed in first 16 kB of flash), which receives the firmware (on UART). The bootloader will install the global read protection on-demand (by a command). For application firmware update, it will use the "Disable Read Protection" (see table 8-4 in XMC4300 manual) flash command before update and the "Resume Protection" (table 8-4) command after successful update.
To be able to exchange the bootloader itself (e.g. by JTAG-interfaced J-Flash), I need to remove the read protection permanently by erasing UCB.
1) I understood that installing the read protection requires writing the User Control Block (UCB) for user 0. It is only possible to write to that UCB 4 times, even if I only access user 0? (User 0 contains the global read protect bit.)
2) Does disabling the read protection automatically erase the full chip or do I need to make that happen manually?
3) When I'd like to attach JTAG again, will a temporarily disabled read protection (by "Disable Read Protection" command) work? I assume the JTAG connect command will perform a controller reset, which will re-enable the read protection again, will it?
4) Does the enabled read protection affect the ability to read flash in my bootloader itself?
Best regards,
Ernie T.
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