FPU Registers remains 0x00000000

Dear support

I am trying to run a fpu instructions on STM32H503CBU6 microcontroller. When I check the values on the FPU registers, it remains 0x00000000 with respect to the particular S<n> registers that I'm trying to use.

Please see the snapshot below.

Here is the assembly code that I use to test the fpu register:


ldr r0,=a0_coeff
ldr r1,[r0]
vmov s1,r1
vcvt.u32.f32 s1,s1
vmov r2,s1
movw r3,#4096
vmov s15,r3
vcvt.f32.u32 s15,s15
vmov r0,s15
vcvt.u32.f32 s15,s15
vmov r1,s15
bx lr

This is the code also to enable the FPU on the microcontroller:

FPU_Enable
ldr r0,=0xE000ED88 ;CPACR
ldr r1,[r0]
ldr r2,=0xFF0FFFFF ;Masking Bits(Clear Bits 23:20)
and r3,r2,r1
ldr r2,=0x00F00000 ;Masking Bits(Sets Bits 23:20)
orr r3,r3,r2
str r3,[r0]

dsb
isb ; Reset pipeline now the FPU is enabled.

bx lr

Hope someone can help me out because I am planning to program a code to run an IIR Filter equation using assembly language.

Thanks and best regards