5.1.4. Remote System Update Configuration Sequence
In the following figure the blue text are states shown in the Configuration Flow Diagram.
Reconfiguration includes the following steps:
- After the device exits power-on-reset (POR), the boot ROM loads flash memory from the first valid decision firmware from one of the copies at addresses 0, 512 K, 1024 K, or 1536 K to initialize the SDM. The same configuration firmware is present in each of these locations. This firmware is part of the initial RSU flash image. ( Refer to Step 2 of Guidelines for Performing Remote System Update Functions for Non-HPS for step-by-step details for programming the initial RSU flash image into the flash.)
If you trigger the reconfiguration with a pulse of nCONFIG low, the SDM loads the decision firmware.
- The optional Direct to Factory pin controls whether the SDM firmware loads the factory or application image. You can assign the Direct to Factory input to any unused SDM pin. The SDM loads the application image if you do not assign this pin.
- The configuration pointer block in the flash device maintains a list of pointers to the application images.
- When loading an application image, the SDM traverses the pointer block in reverse order. The SDM loads the highest priority image. When image loading completes, the device enters user mode.
- If loading the newest (highest priority) image is unsuccessful, the SDM tries the next application image from the list. If none of the application images load successfully, the SDM loads the factory image.
Note: For every unsuccessful configuration, the nSTATUS asserts a low pulse to indicate configuration failure and the SDM proceeds to load the next image automatically, do not assert nCONFIG low to attempt to load the next application image.
- If loading the factory image fails, you can recover by reprogramming the quad SPI flash with the initial RSU flash image using the JTAG interface.
- During the remote update to other application image or factory image, the SDM loads the decision firmware.
You must keep nCONFIG high until the device enters the user mode.
- Keep the nCONFIG signal high after the device powers up and throughout the entire device configuration to load an application or factory image.
- Keep the nCONFIG signal high during the remote update to other application image or factory image by using the RSU_IMAGE_UPDATE command.
You drive nCONFIG low only when the device is in user mode to trigger the reconfiguration.