We want to have serial firmware update feature in our product that is using TMS320F28375S DSP. It is desirable that we don't need to flash the chip manually. The first firmware update should proceed via SCI interface. Therefore we want to ensure that we are selecting the right GPIOs that are default for SCIA update. Accordingly we have adopted following interface:
1- The host for carrying out serial update is connected to the device SCIA pins as GPIO84(SCITXDA/Pin 154) and GPIO85(SCIRXDA/Pin 155). Please note that after boot process the same interface will be used by the HOST for regular communication.
2- The host has digital I/O interface to boot mode select pin 0 i.e. GPIO72 and external reset pin 124.
There is a small confusion that boot mode select pin 1 i.e. GPIO84 is also the default SCIATXDA for serial boot. Accordingly we understand that the following sequence of steps could be followed for successfully carrying out the serial firmware update.
1 - The host should drive the external reset pin (i.e. 124) as low.
2- Boot mode select pin 1 i.e. GPIO72 should be driven low while maintaining GPIO84 in high state. The default UART idle state signaling should itself take care that GPIO84 is driven high.
3- The device should be taken out of reset by driving external reset pin as high.
4- From this point onward the host should be able to proceed with UART protocol for device firmware update.
Kindly confirm if the above understanding is correct?.
It will be nice to know if there are any difference between the bootloader of F28002x series and F2837x series. We have already implemented the serial update application for the former device so it will help in migration to know about any differences.
