What are User Options?

ST’s STM32 ARM devices have areas of flash memory dedicated to programming user configuration data called Option Bytes. Writes to such areas can be sensitive or permanent for some devices, so it is important that the developer is able to write these options in an intuitive way in order to minimize human error. 

How to Use the User Options Commands

Previously an object file was used to support the programming of user options in PEmicro's PROGACMP software and Cyclone standalone mode. A set of three new commands can be found in PROGACMP and the Cyclone Image Creation Utility:

• Create/Modify User Options File (CU)
• Specify User Options File (SU)
• Program User Options (PU)

Create/Modify User Options File (CU)

When the Create/Modify User Options File (CU) command is selected in interactive PROGACMP or the Cyclone Image Creation Utility, it allows the developer to create a new user options (.OPT) file from scratch, or modify an existing .OPT file. This JSON-type file represents the user options that the developer wishes to write, and will be used by the Specify User Options File (SU) and Program User Options (PU) commands later.

The CU dialog lists the names of existing user area(s) and options available on the device. In interactive PROGACMP only, the current value of each option will also be displayed. For each user option, the developer will have the ability to either "Write [a new] Value" or "Leave [the option] Unmodified." New values must be written in hexadecimal format.

If "Import from File" is selected, the developer can choose an existing .OPT file to modify.

The values specified in that file will be displayed in their appropriate fields.

At this point, the developer can choose to modify any contents of the file. The developer can either overwrite the selected file, or save the modified contents to a new filename, leaving the selected file as it was before.

Once all new values have been written in their appropriate fields, the developer can save them to a new user options (.OPT) file.

Specify User Options File (SU) and Program User Options (PU)

Once a user options (.OPT) file has been created, it can be used to program the device's user options in either the PROGACMP software or in Cyclone standalone mode by using the Specify User Options File (SU) and Program User Options (PU) commands.

With the Specify User Options File (SU) command, the developer can select an existing user options (.OPT) file. In interactive PROGACMP, the "User Options File" path will show up in the Configuration window.

Once a file has been specified, the Program User Options (PU) command can be used to write the values specified by the file. For most devices, new option values won't take effect until the device is reset.

Example of SU and PU commands used in Cyclone Image Creation

In CPROGACMP (command-line PROGACMP), user options can be programmed via the SU and PU commands in the following format in a .CFG file:

SU filepath

PU

Where "filepath" is the path to the .OPT file to use (e.g. C:\PEMicro\PROGACMP\supportFiles_ARM\ST\STM32F7 in the example above).