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ST8500

Device architecture

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2.2.3

Debug with serial wire JTAG debug port (SWJ-DP)

The ARM SWJ-DP interface is embedded, and is a combined JTAG and serial wire debug

port that enables either a serial wire debug or a JTAG probe to be connected to the target.

2.2.4

Floating point unit (FPU)

The FPU fully supports single precision add, subtract, multiply, divide, multiply and

accumulate, and square root operations. It also provides conversions between the fixed

point and floating point data formats, and floating point constant instructions.

The FPU provides floating point operations that are compliant with the NSI/IEEE Std 754-

Standard.

The FPU contains 32 single precision extension registers, which can also be accessible as

16 double word registers for load, store, and move operations.

2.2.5

Nested vectored interrupt controller (NVIC)

The ST8500 embeds a NVIC closely integrated with the ARM Cortex™-M4F core. The

NVIC is able to handle 32 maskable interrupts. The software priority level is configurable in

the range of 0 - 31 for each interrupt. A higher level corresponds to a lower priority, so the

level 0 is the highest interrupt priority. In case two or more interrupt lines share the same

software priority level, the hardware priority level is used. Interrupt descriptions and

hardware priorities are shown in Table 3.

Table 3. Interrupt definition and position

Position

Hardware priority

Acronym

Description

Offset from VTOR

-

-3

Reset

Reset

0x00000004

-

-2

NMI

Non maskable interrupt - system error

0x00000008

-

-1

HardFault

All class of fault

0x0000000C

-

0

MemManage

MPU mismatch

0x00000010

-

1

BusFault

Prefetch fault, memory access fault

0x00000014

-

2

UsageFault

Undefined instruction or illegal state

0x00000018

-

-

-

Not present

0x0000001C

-

-

-

Not present

0x00000020

-

-

-

Not present

0x00000024

-

-

-

Not present

0x00000028

-

3

SVCall

System service call via SWI instruction

0x0000002C

-

4

Debug Monitor

Debug monitor

0x00000030

-

-

-

Not present

0x00000034

-

5

PendSV

Pendable request for system service

0x00000038

-

6

Systick

System tick timer

0x0000003C

0

7

lpmode_entry_irq

CRM low power mode enter interrupt

0x00000040

1

8

lpmode_exit_irq

CRM low power mode exit interrupt

0x00000044