JTAG needed pins MTDI and MTDO are also strapping pins
Posted: Sat Oct 28, 2017 4:26 am
Won't using these pins with JTAG interfere with their strapping functions?
Per documentation the MTDI controls the flash voltage VDD_SDIO which seems pretty important to not interfere with.
Also MTDI is internally pulled-up and MTDO is internally pulled-down. This also seems to potentially cause trouble for JTAG functionality.
I saw in another post that the JTAG pins are not re-mappable so I need a solution using those pins.
I am hoping that the answer is not to connect the JTAG after booting. That would be a major inconvenience during development.
If it's possible to reconfigure MTDI and MTDO "after" booting I have a few questions:
1. How do I know in the code when booting is completed?
2. Do I just use normal gpio_xxx functions to reconfigure those pins?
Per documentation the MTDI controls the flash voltage VDD_SDIO which seems pretty important to not interfere with.
Also MTDI is internally pulled-up and MTDO is internally pulled-down. This also seems to potentially cause trouble for JTAG functionality.
I saw in another post that the JTAG pins are not re-mappable so I need a solution using those pins.
I am hoping that the answer is not to connect the JTAG after booting. That would be a major inconvenience during development.
If it's possible to reconfigure MTDI and MTDO "after" booting I have a few questions:
1. How do I know in the code when booting is completed?
2. Do I just use normal gpio_xxx functions to reconfigure those pins?