Confusion with the DBGMCU_IDCODE register.

The die can have multiple steppings (versions) as bugs are fixed, these will be listed in the errata, and ST typically only has a couple

I've used the codes to program PLL's in an assortment of F4-DISCO boards, so I can run each at maximum speeds and bus settings with a single application

The list here isn't comprehensive, at least in entire parts using each die, but is good enough for target practice.

//****************************************************************************
 
void CORECheck(void) // sourcer32@gmail.com
{
 uint32_t cpuid = SCB->CPUID;
 uint32_t var, pat;
 
 printf("CPUID %08X DEVID %03X REVID %04X\n", cpuid, DBGMCU->IDCODE & 0xFFF, (DBGMCU->IDCODE >> 16) & 0xFFFF);
 
 pat = (cpuid & 0x0000000F);
 var = (cpuid & 0x00F00000) >> 20;
 
 if ((cpuid & 0xFF000000) == 0x41000000) // ARM
 {
 switch((cpuid & 0x0000FFF0) >> 4)
 {
 case 0xC20 : printf("Cortex M0 r%dp%d\n", var, pat); break;
 case 0xC60 : printf("Cortex M0+ r%dp%d\n", var, pat); break;
 case 0xC21 : printf("Cortex M1 r%dp%d\n", var, pat); break;
 case 0xC23 : printf("Cortex M3 r%dp%d\n", var, pat); break;
 case 0xC24 : printf("Cortex M4 r%dp%d\n", var, pat); break;
 case 0xC27 : printf("Cortex M7 r%dp%d\n", var, pat); break;
 
 default : printf("Unknown CORE\n");
 }
 }
 else
 printf("Unknown CORE IMPLEMENTER\n");
}
 
//****************************************************************************
 
// FPU Programmer Model
// http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.ddi0489b/Chdhfiah.html
 
void FPUCheck(void) // sourcer32@gmail.com
{
 uint32_t mvfr0;
 
 printf("%08X %08X %08X\n%08X %08X %08X\n",
 *(volatile uint32_t *)0xE000EF34, // FPCCR 0xC0000000
 *(volatile uint32_t *)0xE000EF38, // FPCAR
 *(volatile uint32_t *)0xE000EF3C, // FPDSCR
 *(volatile uint32_t *)0xE000EF40, // MVFR0 0x10110021 vs 0x10110221
 *(volatile uint32_t *)0xE000EF44, // MVFR1 0x11000011 vs 0x12000011
 *(volatile uint32_t *)0xE000EF48); // MVFR2 0x00000040
 
 mvfr0 = *(volatile uint32_t *)0xE000EF40;
 
 switch(mvfr0)
 {
 case 0x00000000 : puts("No FPU"); break;
 case 0x10110021 : puts("FPU-S Single-precision only"); break;
 case 0x10110221 : puts("FPU-D Single-precision and Double-precision"); break;
 default : puts("Unknown FPU");
 }
}
 
//****************************************************************************
 
void IDCODECheck(void) // sourcer32@gmail.com
{
 uint32_t idcode = DBGMCU->IDCODE & 0xFFF;
 
 switch(idcode)
 {
 case 0x423 :
 case 0x433 : printf("STM32F401\n"); break;
 case 0x431 : printf("STM32F411\n"); break;
 case 0x411 : printf("STM32F457\n"); break;
 case 0x413 : printf("STM32F407\n"); break;
 case 0x419 : printf("STM32F429 or F439\n"); break;
 case 0x421 : printf("STM32F446\n"); break;
 case 0x434 : printf("STM32F469\n"); break;
 case 0x441 : printf("STM32F412\n"); break;
 case 0x440 : printf("STM32F030x8\n"); break;
 case 0x442 : printf("STM32F030xC\n"); break;
 case 0x444 : printf("STM32F030x4 or F030x6\n"); break;
 case 0x445 : printf("STM32F070x6\n"); break;
 case 0x448 : printf("STM32F070x8\n"); break;
 case 0x417 : printf("STM32L0 Cat 3\n"); break;
 case 0x447 : printf("STM32L0 Cat 5\n"); break;
 case 0x457 : printf("STM32L011xx\n"); break;
 case 0x435 : printf("STM32L43xxx or L44xxx\n"); break;
 case 0x415 : printf("STM32L475xx, L476xx or L486xx\n"); break;
 case 0x461 : printf("STM32L496xx or L4A6xx\n"); break;
 case 0x462 : printf("STM32L45xxx or L46xxx\n"); break;
 case 0x470 : printf("STM32L4Rxxx or L4Sxxx\n"); break;
 case 0x449 : printf("STM32F74xxx or F75xxx\n"); break;
 case 0x451 : printf("STM32F76xxx or F77xxx\n"); break;
 case 0x452 : printf("STM32F72xxx or F73xxx\n"); break;
 case 0x450 : printf("STM32H7xx\n"); break;
 case 0x480 : printf("STM32H7Ax or H7Bx\n"); break;
 default : printf("Unknown STM32\n");
 }
}
 
//****************************************************************************
 
void SystemDiagnostic(void)
{
 printf("\n\nCore=%d, %d MHz\n", SystemCoreClock, SystemCoreClock / 1000000);
 CORECheck();
 IDCODECheck();
 FPUCheck();
 printf("APB1=%d\n", HAL_RCC_GetPCLK1Freq());
 printf("APB2=%d\n", HAL_RCC_GetPCLK2Freq());
}
 
//****************************************************************************

> Why is DBGMCU_IDCODE value different when I read it from executing code

Show that code.

JW

Actually, there is no code. I just run the debugger in Eclipse and view memory location 0xE0042000 (for the st32L073/051 0x40015800).

I recently added the ST32L476RG (from a Nucleo board).

STLINK reports ID 415 Rev4, STLINK memory read returns 1007 6415

Memory in debugger displays: 1564 0710

AUUUG! I AM EMBARRASSED! :squinting_face_with_tongue:

I forgot the byte order. 1564 0710 is 1007 6415.

So Sorry! I really thought I had found a way to determine the part number.