SPRACM8A June 2019 – January 2021 OMAP-L132 , OMAP-L132 , OMAP-L138 , OMAP-L138 , TMS320C6742 , TMS320C6742 , TMS320C6746 , TMS320C6746 , TMS320C6748 , TMS320C6748
There are two types of reset:
It is important for the device to experience a POR when initially powered up. This will clear the emulation and PLL logic, as well as latch the boot pins correctly. Therefore, make sure TRST is externally pulled down on your board. Not doing so can be the cause of many boot related problems.
When the device is held in reset, all device I/Os are internally pulled down.
For the boot and configuration pins, if they are both routed out and 3-stated (not driven), it is strongly recommended that an external pullup/pulldown resistor be implemented. Although, internal pullup/pulldown resistors exist on these pins and they may match the desired configuration value, providing external connectivity can help ensure that valid logic levels are latched on these device boot and configuration pins. In addition, applying external pullup/pulldown resistors on the boot and configuration pins adds convenience to the user in debugging and flexibility in switching operating modes.
For details on how to choose values to oppose the internal pullup/pulldown resistors, see the Pullup/Pulldown Resistors section of the OMAP-L138 C6000™ DSP+ ARM® Processor Data Manual.