Page 1 of 1

JTAG, VSIP and EMAC pins

Posted: Tue Jun 05, 2018 8:14 am
by habibh
Hello..

I am going to use ESP32-PICO-D4 in my project with external flash and sRAM. I want to use VSPI in my project for communicating with external flash and sRAM. The SPI pins are already used in ESP32-PICO-D4 for connecting embedded flash and these pins cannot be used. So my question is if i am using VSPI pins and JTAG pins than i will not be able to use Ethernet funcction of ESP32-PICO-D4 in my project ?
In the attachment I have highlighted the pins that are shairing the same functionality..

Regards:
Habib

Re: JTAG, VSIP and EMAC pins

Posted: Fri Oct 19, 2018 6:27 pm
by phatpaul
Seems I'm unable to use JTAG and Ethernet at the same time.
I'm not sure what's going on exactly.

I don't see how the pins are shared because I'm not using GPIO13/MTCK for anything other than JTAG (it is apparently not required for Ethernet RMII, although some documentation lists it as EMAC_RX_ER).

When I start-up with JTAG connected, the emacT task fails to init the PHY chip (LAN8720).

But if I temporarily disconnect JTAG, then emac starts up fine and then I can reconnect JTAG and both works fine.
Currently it's just an annoyance for me, not a show-stopper. But I'd like to know how to fix it.