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Standalone mode of ez-host to co processor(HPI) mode

Last Updated: November 28, 2013

Is it possible to change the standalone mode of ez-host to co processor(HPI) mode without rebooting the board?


No, because the mode it boots into is determined by the TTL voltage level of GPIO[31:30] at the time nRESET is deasserted. After a reset pin event occurs, the BIOS bootup procedure executes for up to 3 ms. GPIO[31:30] are sampled by the BIOS during bootup only. After bootup these pins are available to the application as GPIOs. So it has to reset to change the mode.

However, the OTG-Host products can also operate in a mode where standalone code is running on the OTG-Host and is communicating over the coprocessor interface to an external master.

In this case the entire USB stack, including the device driver, can be running on OTG-Host, which reduces the bandwidth requirements on the external processor. There are two different ways of accomplishing this type of configuration. The first method is to operate fully in standalone mode, where the firmware is stored in the EEPROM. When running, the developer’s firmware can communicate over one of the standard interfaces or create a new interface using GPIO pins. Alternately the firmware can call the routine in the BIOS that enables and configures the coprocessor interface. Once this is done, the OTG-Host part will accept standard LCP commands over the defined coprocessor interface.
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