Block Diagram#
Firmware File Format (RPS)#
The NWP Bootloader uses a proprietary format for NWP and M4 its upgrade images, called RPS . These files have extension .rps. The RPS Format is a binary executable format understood by the Bootloader to perform the required integrity and authenticity checks and load and execute the application.
The Firmware Image in the RPS format includes an RPS header, boot descriptors, the application's binary image, and an optional trailer (digital signature).
RPS Header Format#
The following image shows the RPS header format with the fields present in it.
| S.N. | Field | Size (in bytes) | Description |
|---|---|---|---|
| 1 | Control flag | 2 |
Bit map which indicates image information:
|
| 2 | SHA Type | 2 |
Represents the SHA size used to compute the digest for the digital signature
|
| 3 | Magic Word | 4 | 0x900D900D |
| 4 | Image Size | 4 | Size of the image |
| 5 | Firmware Version | 4 | Firmware version (Major number + Minor number + Security version number + Build number) |
| 6 | Flash Location | 4 | Flash address where image is stored |
| 7 | CRC | 4 | CRC of the image |
| 8 | MIC | 16 | MIC of the image |
| 9 | Reserved | 4 | Reserved |
| 10 | Ext. Firmware version | 4 | Additional details of FW version such as patch number, Customer ID, rom_id and chip ID |
| 11 | Reserved | 16 | Reserved |
| Note: In case of combined image (NWP + M4) – the Reserved (16 Bytes) field present at the end of the RPS header will be replaced with the following. | |||
| 11 | Combine Image Size | 4 | Size of the combined image (NWP + M4) |
| 12 | Combined Image Sign | 1 |
Bitmap which indicates whether the combined image is signed. BIT(0):
|
| 13 | Reserved | 11 | Reserved |