---
title: "Peripheral registers"
---

# Peripheral registers

Peripheral registers and bit fields from CMSIS-SVD files in the Registers editor, as a hover in C, and as a Peripherals scope while debugging, and registers added to the device from SVD overlays or IAR .ddf files.

The module reads the device's CMSIS-SVD file and shows its peripherals, registers and bit fields where you need them, as Keil's System Viewer, IAR's Register window and STM32CubeIDE's SFRs view do.

## Where registers appear

- The **Registers** editor, opened from any `.svd` file or with **Browse Device Registers**: peripherals, registers and fields with their descriptions, addresses and access.
- A **hover in C and C++**: hover `GPIOA->MODER` to see the peripheral, register and field details, with a link to open them in the Registers editor.
- A **Peripherals** scope in the Variables view while debugging, read at each halt and writable, next to the core **Registers** scope.

![The Peripherals scope in Variables while debugging, with a USART status register expanded into its bit fields.](https://neuralinverse.com/docs-images/modules/embedded/peripherals-scope.webp)

## Which SVD file is used

1. `neuralInverse.embedded.svdFile`, absolute or relative to the CMake source folder, or a launch configuration's `svdFile`;
2. else the SVD file of `neuralInverse.embedded.device` from its installed device family pack ([Device packs, pins and clocks](https://neuralinverse.com/docs/modules/embedded/devices/));
3. else the first `.svd` file in the project.

Right-click an `.svd` file in the Explorer and choose **Use as SVD File for Debugging** to set it. In a TRACE32 session the Peripherals scope also comes from the SVD file.

State: unit and rendering tests with an SVD fixture of a few peripherals; the hover verified with fakes only. In the running app on Linux, ST's STM32F407 SVD (78 peripherals) was shown with two overlays and the Peripherals view of a QEMU session. **A full vendor SVD file (load time, size) and the Peripherals scope on a live target are not verified.**

## Add registers to the device

For an ASIC or FPGA on the memory bus, such as a gate driver on the FSMC, or an IAR register override, **Add Registers to Device (SVD or IAR .ddf)...** adds files to `neuralInverse.embedded.svdOverlays`, as IAR C-SPY's SFR Setup adds registers:

- CMSIS-SVD files with your own peripherals;
- IAR device description files (`.ddf`): their `[Sfr]` registers, `[SfrGroupInfo]` groups and `[SfrInclude]` includes.

The added peripherals appear with the device's in the Registers editor and the Peripherals scope. A peripheral with the name of one of the device's replaces it.

![The Registers editor showing a peripheral added from an IAR .ddf overlay file next to the device SVD peripherals.](https://neuralinverse.com/docs-images/modules/embedded/register-overlay.webp)

State: unit and Electron tests; the running app with ST's STM32F407 SVD and two overlays. The `.ddf` reader is **not yet verified against IAR Embedded Workbench** or an IAR-shipped file, and overlay registers have not been read on a target.