how to reset NET+OS NVRAM to defaults due forgotten or unknown password or invalid baudrate

When your NET+OS firmware device does not boot anymore and you are trying How to recover a Digi Connect (Wi-)ME (9210), (Wi-)EM and (Wi-)SP JTAG'less C module, you may manage to upload a firmware image.bin, however it might still not boot due to wired NVRAM settings like wrong baud rate. When trying to change the NVRAM settings from the serial console or CLI you might need to enter a root password which could also be wrong in NVRAM or just was set wrong or forgotten.

To work around this you may upload a temporary firmware file image.bin which when executed will reset some of the NVRAM parameters (dev board parameters) to default values, but leaves other parameters like MAC address and IP settings untouched.

To create such a firmware image, use the NET+OS FTP Server File System Sample and modify root.c to include following code in applicationStart() before the FTP server is started:

devBoardParamsType nvParams;
if (customizeReadDevBoardParams(&nvParams)) printf("unable to read dev board params\n");
/* continue no matter if Read() failed */
if (customizeUseDefaultParams(&nvParams)) printf("unable to use defaults\n");
/* continue no matter if usedefaults() failed */
if (customizeWriteDevBoardParams(&nvParams)) printf("unable to write dev board params\n");
else printf("NVRAM settings reset to default. Reboot/reset/powercycle the device\n");

You may also download a ready to use image.bin for Connect ME (ARM7 NS7520 processor).

Upload the image.bin via FTP, or if not accessible due to missing password use TFTP recovery method. Wait about 30 seconds to get it programmed into flash (check serial output if available for progress). Power cycle the module to get the password reset image.bin executed and wait about 30seconds to have everything started. Now use FTP or TFTP (recovery mode) to install your custom image.bin. Your password should be reset to password also baudrate to 9600.