No coprocessor UsageFault

bamdadslr — Thu, 07 Jul 2022 21:14:28 GMT

Hi,

I am running a code on a LPC4088 board. In part of this code, when I want to initialize the ABI protocol, the IDE gave a hard fault error. Looking into a suggestion provided here http://chmorgan.blogspot.com/2013/06/debugging-imprecise-bus-access-fault-on.html, I added "*(uint8_t *)0xE000E008 |= (1<<1);" to main(). Now, what I get as the error is NOCP: No coprocessor Usagefault. The processor does not support coprocessor instructions.

Any ideas on how to solve this is greatly appreciated.

Note: based on this document https://web.eecs.umich.edu/~prabal/teaching/eecs373-f10/readings/ARMv7-M_ARM.pdf, I tried to monitor CPACR register, this is the value in memory starting from 0xE000ED88: 00F00000 00000000 00000800 00000000 00000000.

Re: No coprocessor UsageFault

xiangjun_rong — Fri, 08 Jul 2022 04:09:46 GMT

Hi,

As you know that the LPC4088 uses Cortex-M4 core, the register ACTLR is located at 0xE000E008 address.

0xE000E008 ACTLR RW Privileged 0x00000000 Auxiliary Control Register

The CPACR is located at address 0xE000ED88.

0xE000ED88 CPACR RW 0x00000000 Coprocessor Access Control Register

The bit 2 in ACTLR register is DISDEFWBUF, which is explained as

"When set to 1, disables write buffer use during default memory map accesses. This causes all
BusFaults to be precise BusFaults but decreases performance because any store to memory must
complete before the processor can execute the next instruction.
Note
This bit only affects write buffers implemented in the Cortex-M4 processor.

LPC MicrocontrollersのトピックRe: No coprocessor UsageFault

No coprocessor UsageFault

Re: No coprocessor UsageFault